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717 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Chang S. Bae
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15d51a2f6f |
x86/fpu/xstate: Introduce xfeature order table and accessor macro
The kernel has largely assumed that higher xstate component numbers correspond to later offsets in the buffer. However, this assumption no longer holds for the non-compacted format, where a newer state component may have a lower offset. When iterating over xstate components in offset order, using the feature number as an index may be misleading. At the same time, the CPU exposes each component’s size and offset based on its feature number, making it a key for state information. To provide flexibility in handling xstate ordering, introduce a mapping table: feature order -> feature number. The table is dynamically populated based on the CPU-exposed features and is sorted in offset order at boot time. Additionally, add an accessor macro to facilitate sequential traversal of xstate components based on their actual buffer positions, given a feature bitmask. This accessor macro will be particularly useful for computing custom non-compacted format sizes and iterating over xstate offsets in non-compacted buffers. Suggested-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20250320234301.8342-3-chang.seok.bae@intel.com |
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Chang S. Bae
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031b33ef1a |
x86/fpu/xstate: Remove xstate offset check
Traditionally, new xstate components have been assigned sequentially, aligning feature numbers with their offsets in the XSAVE buffer. However, this ordering is not architecturally mandated in the non-compacted format, where a component's offset may not correspond to its feature number. The kernel caches CPUID-reported xstate component details, including size and offset in the non-compacted format. As part of this process, a sanity check is also conducted to ensure alignment between feature numbers and offsets. This check was likely intended as a general guideline rather than a strict requirement. Upcoming changes will support out-of-order offsets. Remove the check as becoming obsolete. Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20250320234301.8342-2-chang.seok.bae@intel.com |
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Ingo Molnar
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78255eb239 |
x86/msr: Rename 'wrmsrl()' to 'wrmsrq()'
Suggested-by: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juergen Gross <jgross@suse.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Xin Li <xin@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> |
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Ingo Molnar
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c435e608cf |
x86/msr: Rename 'rdmsrl()' to 'rdmsrq()'
Suggested-by: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juergen Gross <jgross@suse.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Xin Li <xin@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> |
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Chao Gao
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878477a595 |
x86/fpu: Update the outdated comment above fpstate_init_user()
fpu_init_fpstate_user() was removed in:
commit
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Chao Gao
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dda366083e |
x86/fpu/xstate: Fix inconsistencies in guest FPU xfeatures
Guest FPUs manage vCPU FPU states. They are allocated via
fpu_alloc_guest_fpstate() and are resized in fpstate_realloc() when XFD
features are enabled.
Since the introduction of guest FPUs, there have been inconsistencies in
the kernel buffer size and xfeatures:
1. fpu_alloc_guest_fpstate() uses fpu_user_cfg since its introduction. See:
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Borislav Petkov (AMD)
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4348e91778 |
x86/fpu: Clarify the "xa" symbolic name used in the XSTATE* macros
Tie together the %[xa] in the XSAVE/XRSTOR definitions with the respective usage in the asm macros so that it is perfectly clear. No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> |
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Uros Bizjak
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2883b4c216 |
x86/fpu: Use XSAVE{,OPT,C,S} and XRSTOR{,S} mnemonics in xstate.h
Current minimum required version of binutils is 2.25, which
supports XSAVE{,OPT,C,S} and XRSTOR{,S} instruction mnemonics.
Replace the byte-wise specification of XSAVE{,OPT,C,S}
and XRSTOR{,S} with these proper mnemonics.
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250313130251.383204-1-ubizjak@gmail.com
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Eric Biggers
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d021985504 |
x86/fpu: Improve crypto performance by making kernel-mode FPU reliably usable in softirqs
Background:
===========
Currently kernel-mode FPU is not always usable in softirq context on
x86, since softirqs can nest inside a kernel-mode FPU section in task
context, and nested use of kernel-mode FPU is not supported.
Therefore, x86 SIMD-optimized code that can be called in softirq context
has to sometimes fall back to non-SIMD code. There are two options for
the fallback, both of which are pretty terrible:
(a) Use a scalar fallback. This can be 10-100x slower than vectorized
code because it cannot use specialized instructions like AES, SHA,
or carryless multiplication.
(b) Execute the request asynchronously using a kworker. In other
words, use the "crypto SIMD helper" in crypto/simd.c.
Currently most of the x86 en/decryption code (skcipher and aead
algorithms) uses option (b), since this avoids the slow scalar fallback
and it is easier to wire up. But option (b) is still really bad for its
own reasons:
- Punting the request to a kworker is bad for performance too.
- It forces the algorithm to be marked as asynchronous
(CRYPTO_ALG_ASYNC), preventing it from being used by crypto API
users who request a synchronous algorithm. That's another huge
performance problem, which is especially unfortunate for users who
don't even do en/decryption in softirq context.
- It makes all en/decryption operations take a detour through
crypto/simd.c. That involves additional checks and an additional
indirect call, which slow down en/decryption for *everyone*.
Fortunately, the skcipher and aead APIs are only usable in task and
softirq context in the first place. Thus, if kernel-mode FPU were to be
reliably usable in softirq context, no fallback would be needed.
Indeed, other architectures such as arm, arm64, and riscv have already
done this.
Changes implemented:
====================
Therefore, this patch updates x86 accordingly to reliably support
kernel-mode FPU in softirqs.
This is done by just disabling softirq processing in kernel-mode FPU
sections (when hardirqs are not already disabled), as that prevents the
nesting that was problematic.
This will delay some softirqs slightly, but only ones that would have
otherwise been nested inside a task context kernel-mode FPU section.
Any such softirqs would have taken the slow fallback path before if they
tried to do any en/decryption. Now these softirqs will just run at the
end of the task context kernel-mode FPU section (since local_bh_enable()
runs pending softirqs) and will no longer take the slow fallback path.
Alternatives considered:
========================
- Make kernel-mode FPU sections fully preemptible. This would require
growing task_struct by another struct fpstate which is more than 2K.
- Make softirqs save/restore the kernel-mode FPU state to a per-CPU
struct fpstate when nested use is detected. Somewhat interesting, but
seems unnecessary when a simpler solution exists.
Performance results:
====================
I did some benchmarks with AES-XTS encryption of 16-byte messages (which is
unrealistically small, but this makes it easier to see the overhead of
kernel-mode FPU...). The baseline was 384 MB/s. Removing the use of
crypto/simd.c, which this work makes possible, increases it to 487 MB/s,
a +27% improvement in throughput.
CPU was AMD Ryzen 9 9950X (Zen 5). No debugging options were enabled.
[ mingo: Prettified the changelog and added performance results. ]
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/r/20250304204954.3901-1-ebiggers@kernel.org
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Chang S. Bae
|
69a2fdf446 |
x86/fpu/xstate: Simplify print_xstate_features()
print_xstate_features() currently invokes print_xstate_feature() multiple times on separate lines, which can be simplified in a loop. print_xstate_feature() already checks the feature's enabled status and is only called within print_xstate_features(). Inline print_xstate_feature() and iterate over features in a loop to streamline the enabling message. No functional changes. Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/r/20250227184502.10288-2-chang.seok.bae@intel.com |
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Chang S. Bae
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dc8aa31a7a |
x86/fpu: Refine and simplify the magic number check during signal return
Before restoring xstate from the user space buffer, the kernel performs
sanity checks on these magic numbers: magic1 in the software reserved
area, and magic2 at the end of XSAVE region.
The position of magic2 is calculated based on the xstate size derived
from the user space buffer. But, the in-kernel record is directly
available and reliable for this purpose.
This reliance on user space data is also inconsistent with the recent
fix in:
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Stanislav Spassov
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1937e18cc3 |
x86/fpu: Fix guest FPU state buffer allocation size
Ongoing work on an optimization to batch-preallocate vCPU state buffers
for KVM revealed a mismatch between the allocation sizes used in
fpu_alloc_guest_fpstate() and fpstate_realloc(). While the former
allocates a buffer sized to fit the default set of XSAVE features
in UABI form (as per fpu_user_cfg), the latter uses its ksize argument
derived (for the requested set of features) in the same way as the sizes
found in fpu_kernel_cfg, i.e. using the compacted in-kernel
representation.
The correct size to use for guest FPU state should indeed be the
kernel one as seen in fpstate_realloc(). The original issue likely
went unnoticed through a combination of UABI size typically being
larger than or equal to kernel size, and/or both amounting to the
same number of allocated 4K pages.
Fixes:
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Eric Biggers
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ccb7735a1e |
x86/fpu: Fully optimize out WARN_ON_FPU()
Currently WARN_ON_FPU evaluates its argument even if
CONFIG_X86_DEBUG_FPU is disabled, which adds unnecessary instructions to
several functions, for example kernel_fpu_begin(). Fix this by using
BUILD_BUG_ON_INVALID(x) in the no-debug case rather than (void)(x).
Fixes:
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Linus Torvalds
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48795f90cb |
- Remove the less generic CPU matching infra around struct x86_cpu_desc and
use the generic struct x86_cpu_id thing - Remove magic naked numbers for CPUID functions and use proper defines of the prefix CPUID_LEAF_*. Consolidate some of the crazy use around the tree - Smaller cleanups and improvements -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmePjeIACgkQEsHwGGHe VUqRBA//TinKFcWagaQB3lsnoBRwqyg6JJZIBNMF9sBMDD9HnvEZ/JduC+3+g1rx iztuCmRSgQsi/QvRaEFNuDMOgk6gACyXxi7Uf6eXsQkSlsZFViaqbXsy9kqslRbl 7QP1NS1sfdSd42JPp2UZT/lg9kluuVnn5b40zZIwy2AAzwrNFfZAS4Yg7Qe4XQDF xBcHi8MAF+LTm5Tv0hLmx2UcfZLhi7hXy8mTAIFS0Liww+Y5qaam33xw9KxNU5lZ tVepzY5my43pRs4MB1CvaQCiZ84GxvAVqz3JYsg5YhVp45xh7P2WtjBeeOqLljaW MkWnDLOmlaD4Y0kL4QA3ReyBVux54RbDGKC0E/t5fwYlk3dQ7gYwSEvh5358R+0z kwxw3NdnNngoLRXAX45EonSxj36jb6KCBHAGqXSfL73OOt30RWCqknEnixcOp/BP chNxCiIx7qko+rAYOD62QkguEEPFdb8roeayhIKtiKL5zUwQAr+jt/pKVx2htWLi xxqSaVoCFu4edWpsEJnanqhS0Es0v7YiBU3jDC37rZJ+dtzf0C2ewD7Nb1g+wUTn NzDkmt58hQW4jBxoxHBIclLfhEETISTEGAAObTa5I5r8IDb7Dv+ZnSv7RfjoR9fL RWMz1bJ1Scem+Fx7fc/IRJFSElC41giSwFlhThHdAzI1m95zJN8= =9Hdg -----END PGP SIGNATURE----- Merge tag 'x86_cpu_for_v6.14_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cpuid updates from Borislav Petkov: - Remove the less generic CPU matching infra around struct x86_cpu_desc and use the generic struct x86_cpu_id thing - Remove magic naked numbers for CPUID functions and use proper defines of the prefix CPUID_LEAF_*. Consolidate some of the crazy use around the tree - Smaller cleanups and improvements * tag 'x86_cpu_for_v6.14_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/cpu: Make all all CPUID leaf names consistent x86/fpu: Remove unnecessary CPUID level check x86/fpu: Move CPUID leaf definitions to common code x86/tsc: Remove CPUID "frequency" leaf magic numbers. x86/tsc: Move away from TSC leaf magic numbers x86/cpu: Move TSC CPUID leaf definition x86/cpu: Refresh DCA leaf reading code x86/cpu: Remove unnecessary MwAIT leaf checks x86/cpu: Use MWAIT leaf definition x86/cpu: Move MWAIT leaf definition to common header x86/cpu: Remove 'x86_cpu_desc' infrastructure x86/cpu: Move AMD erratum 1386 table over to 'x86_cpu_id' x86/cpu: Replace PEBS use of 'x86_cpu_desc' use with 'x86_cpu_id' x86/cpu: Expose only stepping min/max interface x86/cpu: Introduce new microcode matching helper x86/cpufeature: Document cpu_feature_enabled() as the default to use x86/paravirt: Remove the WBINVD callback x86/cpufeatures: Free up unused feature bits |
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Rick Edgecombe
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a9d9c33132 |
x86/fpu: Ensure shadow stack is active before "getting" registers
The x86 shadow stack support has its own set of registers. Those registers
are XSAVE-managed, but they are "supervisor state components" which means
that userspace can not touch them with XSAVE/XRSTOR. It also means that
they are not accessible from the existing ptrace ABI for XSAVE state.
Thus, there is a new ptrace get/set interface for it.
The regset code that ptrace uses provides an ->active() handler in
addition to the get/set ones. For shadow stack this ->active() handler
verifies that shadow stack is enabled via the ARCH_SHSTK_SHSTK bit in the
thread struct. The ->active() handler is checked from some call sites of
the regset get/set handlers, but not the ptrace ones. This was not
understood when shadow stack support was put in place.
As a result, both the set/get handlers can be called with
XFEATURE_CET_USER in its init state, which would cause get_xsave_addr() to
return NULL and trigger a WARN_ON(). The ssp_set() handler luckily has an
ssp_active() check to avoid surprising the kernel with shadow stack
behavior when the kernel is not ready for it (ARCH_SHSTK_SHSTK==0). That
check just happened to avoid the warning.
But the ->get() side wasn't so lucky. It can be called with shadow stacks
disabled, triggering the warning in practice, as reported by Christina
Schimpe:
WARNING: CPU: 5 PID: 1773 at arch/x86/kernel/fpu/regset.c:198 ssp_get+0x89/0xa0
[...]
Call Trace:
<TASK>
? show_regs+0x6e/0x80
? ssp_get+0x89/0xa0
? __warn+0x91/0x150
? ssp_get+0x89/0xa0
? report_bug+0x19d/0x1b0
? handle_bug+0x46/0x80
? exc_invalid_op+0x1d/0x80
? asm_exc_invalid_op+0x1f/0x30
? __pfx_ssp_get+0x10/0x10
? ssp_get+0x89/0xa0
? ssp_get+0x52/0xa0
__regset_get+0xad/0xf0
copy_regset_to_user+0x52/0xc0
ptrace_regset+0x119/0x140
ptrace_request+0x13c/0x850
? wait_task_inactive+0x142/0x1d0
? do_syscall_64+0x6d/0x90
arch_ptrace+0x102/0x300
[...]
Ensure that shadow stacks are active in a thread before looking them up
in the XSAVE buffer. Since ARCH_SHSTK_SHSTK and user_ssp[SHSTK_EN] are
set at the same time, the active check ensures that there will be
something to find in the XSAVE buffer.
[ dhansen: changelog/subject tweaks ]
Fixes:
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Dave Hansen
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e5d3a57891 |
x86/cpu: Make all all CPUID leaf names consistent
The leaf names are not consistent. Give them all a CPUID_LEAF_ prefix for consistency and vertical alignment. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Dave Jiang <dave.jiang@intel.com> # for ioatdma bits Link: https://lore.kernel.org/all/20241213205040.7B0C3241%40davehans-spike.ostc.intel.com |
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Dave Hansen
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588e148d8b |
x86/fpu: Remove unnecessary CPUID level check
The CPUID level dependency table will entirely zap X86_FEATURE_XSAVE if the CPUID level is too low. This code is unreachable. Kill it. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Chang S. Bae <chang.seok.bae@intel.com> Link: https://lore.kernel.org/all/20241213205038.6E71F9A4%40davehans-spike.ostc.intel.com |
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Dave Hansen
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754aaac3bb |
x86/fpu: Move CPUID leaf definitions to common code
Move the XSAVE-related CPUID leaf definitions to common code. Then, use the new definition to remove the last magic number from the CPUID level dependency table. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Link: https://lore.kernel.org/all/20241213205037.43C57CDE%40davehans-spike.ostc.intel.com |
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Aruna Ramakrishna
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ae6012d72f |
x86/pkeys: Ensure updated PKRU value is XRSTOR'd
When XSTATE_BV[i] is 0, and XRSTOR attempts to restore state component
'i' it ignores any value in the XSAVE buffer and instead restores the
state component's init value.
This means that if XSAVE writes XSTATE_BV[PKRU]=0 then XRSTOR will
ignore the value that update_pkru_in_sigframe() writes to the XSAVE buffer.
XSTATE_BV[PKRU] only gets written as 0 if PKRU is in its init state. On
Intel CPUs, basically never happens because the kernel usually
overwrites the init value (aside: this is why we didn't notice this bug
until now). But on AMD, the init tracker is more aggressive and will
track PKRU as being in its init state upon any wrpkru(0x0).
Unfortunately, sig_prepare_pkru() does just that: wrpkru(0x0).
This writes XSTATE_BV[PKRU]=0 which makes XRSTOR ignore the PKRU value
in the sigframe.
To fix this, always overwrite the sigframe XSTATE_BV with a value that
has XSTATE_BV[PKRU]==1. This ensures that XRSTOR will not ignore what
update_pkru_in_sigframe() wrote.
The problematic sequence of events is something like this:
Userspace does:
* wrpkru(0xffff0000) (or whatever)
* Hardware sets: XINUSE[PKRU]=1
Signal happens, kernel is entered:
* sig_prepare_pkru() => wrpkru(0x00000000)
* Hardware sets: XINUSE[PKRU]=0 (aggressive AMD init tracker)
* XSAVE writes most of XSAVE buffer, including
XSTATE_BV[PKRU]=XINUSE[PKRU]=0
* update_pkru_in_sigframe() overwrites PKRU in XSAVE buffer
... signal handling
* XRSTOR sees XSTATE_BV[PKRU]==0, ignores just-written value
from update_pkru_in_sigframe()
Fixes:
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Aruna Ramakrishna
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6a1853bdf1 |
x86/pkeys: Change caller of update_pkru_in_sigframe()
update_pkru_in_sigframe() will shortly need some information which is only available inside xsave_to_user_sigframe(). Move update_pkru_in_sigframe() inside the other function to make it easier to provide it that information. No functional changes. Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/all/20241119174520.3987538-2-aruna.ramakrishna%40oracle.com |
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Linus Torvalds
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70f43ea3a3 |
Updates for x86 memory management:
- Make LAM enablement safe vs. kernel threads using a process mm
temporarily as switching back to the process would not update CR3 and
therefore not enable LAM causing faults in user space when using tagged
pointers. Cure it by synchronizing LAM enablement via IPIs to all CPUs
which use the related mm.
- Cure a LAM harmless inconsistency between CR3 and the state during
context switch. It's both confusing and prone to lead to real bugs
- Handle alt stack handling for threads which run with a non-zero
protection key. The non-zero key prevents the kernel to access the
alternate stack. Cure it by temporarily enabling all protection keys for
the alternate stack setup/restore operations.
- Provide a EFI config table identity mapping for kexec kernel to prevent
kexec fails because the new kernel cannot access the config table array
- Use GB pages only when a full GB is mapped in the identity map as
otherwise the CPU can speculate into reserved areas after the end of
memory which causes malfunction on UV systems.
- Remove the noisy and pointless SRAT table dump during boot
- Use is_ioremap_addr() for iounmap() address range checks instead of
high_memory. is_ioremap_addr() is more precise.
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Merge tag 'x86-mm-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 memory management updates from Thomas Gleixner:
- Make LAM enablement safe vs. kernel threads using a process mm
temporarily as switching back to the process would not update CR3 and
therefore not enable LAM causing faults in user space when using
tagged pointers. Cure it by synchronizing LAM enablement via IPIs to
all CPUs which use the related mm.
- Cure a LAM harmless inconsistency between CR3 and the state during
context switch. It's both confusing and prone to lead to real bugs
- Handle alt stack handling for threads which run with a non-zero
protection key. The non-zero key prevents the kernel to access the
alternate stack. Cure it by temporarily enabling all protection keys
for the alternate stack setup/restore operations.
- Provide a EFI config table identity mapping for kexec kernel to
prevent kexec fails because the new kernel cannot access the config
table array
- Use GB pages only when a full GB is mapped in the identity map as
otherwise the CPU can speculate into reserved areas after the end of
memory which causes malfunction on UV systems.
- Remove the noisy and pointless SRAT table dump during boot
- Use is_ioremap_addr() for iounmap() address range checks instead of
high_memory. is_ioremap_addr() is more precise.
* tag 'x86-mm-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/ioremap: Improve iounmap() address range checks
x86/mm: Remove duplicate check from build_cr3()
x86/mm: Remove unused NX related declarations
x86/mm: Remove unused CR3_HW_ASID_BITS
x86/mm: Don't print out SRAT table information
x86/mm/ident_map: Use gbpages only where full GB page should be mapped.
x86/kexec: Add EFI config table identity mapping for kexec kernel
selftests/mm: Add new testcases for pkeys
x86/pkeys: Restore altstack access in sigreturn()
x86/pkeys: Update PKRU to enable all pkeys before XSAVE
x86/pkeys: Add helper functions to update PKRU on the sigframe
x86/pkeys: Add PKRU as a parameter in signal handling functions
x86/mm: Cleanup prctl_enable_tagged_addr() nr_bits error checking
x86/mm: Fix LAM inconsistency during context switch
x86/mm: Use IPIs to synchronize LAM enablement
|
||
|
Linus Torvalds
|
c3056a7d14 |
Provide FPU buffer layout in core dumps:
Debuggers have guess the FPU buffer layout in core dumps, which is error prone. This is because AMD and Intel layouts differ. To avoid buggy heuristics add a ELF section which describes the buffer layout which can be retrieved by tools. -----BEGIN PGP SIGNATURE----- iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAmbpOuwTHHRnbHhAbGlu dXRyb25peC5kZQAKCRCmGPVMDXSYoTRAEACGHPdAYFp5A396c9qUbHUE2gEKIad2 iuq15TZKLPY/LFqfTwnkp9/nqKtZ0gj4D6XCIucWZjwWJuPgvgGf/tC9Fk+H+C6X 9+rycP3GdqxU28qLxA428SN2Pg3lvqG4rryVWeHUXQ4x8A0DSMV+3pkNY5YgJ+2+ fTzNzVi2tkPRAXhKmj3EdcFcgDPiFQBMm1QNBpc+FqrXk4rjJb9Axln0oT8xemDv TtJ5BMhFpR73naaiS4IrK8Tk3oFCa8CmafCQfl1zAOor/+EemPQKwMuGeiXE7dLG eE+OTw5zuxYwlc9WoaPmM/ZiEc5JptpHQUtyHDBN7BaK87VKjsupAXXVOh6XMRCt R2coqq7fqDqMANwWpUKddky3vSwbst1GZpXGAENOy64yU4VoFutr616WSj3sJfUi knBauPqLAFeZLhMn/kKr5a0rBgm7VuQSlGPYEhqVdaM3Eb/zJEupFL/bTpqQbbz/ 8lo2hYcfDslhShcEZYBwm4eUg+ytZ96K3ciZ5YgNih9LFBxEOo0SY1CqbQJiRtpB 3DmgldYtzRdQq5/JtFGNv717uMESn5khG3qHUpXtrDhWfD8spMWiY1yO/cwWvLFJ ZS5ATp1dAt1Pbv2MC6r9jQBbW3V7xNNAOJdzUvIZPP04PKeV0ObFOplxhabOzUDj OLquyIrjpxeisg== =Vqqo -----END PGP SIGNATURE----- Merge tag 'x86-fpu-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fpu updates from Thomas Gleixner: "Provide FPU buffer layout in core dumps: Debuggers have guess the FPU buffer layout in core dumps, which is error prone. This is because AMD and Intel layouts differ. To avoid buggy heuristics add a ELF section which describes the buffer layout which can be retrieved by tools" * tag 'x86-fpu-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/elf: Add a new FPU buffer layout info to x86 core files |
||
|
Mitchell Levy
|
2848ff28d1 |
x86/fpu: Avoid writing LBR bit to IA32_XSS unless supported
There are two distinct CPU features related to the use of XSAVES and LBR:
whether LBR is itself supported and whether XSAVES supports LBR. The LBR
subsystem correctly checks both in intel_pmu_arch_lbr_init(), but the
XSTATE subsystem does not.
The LBR bit is only removed from xfeatures_mask_independent when LBR is not
supported by the CPU, but there is no validation of XSTATE support.
If XSAVES does not support LBR the write to IA32_XSS causes a #GP fault,
leaving the state of IA32_XSS unchanged, i.e. zero. The fault is handled
with a warning and the boot continues.
Consequently the next XRSTORS which tries to restore supervisor state fails
with #GP because the RFBM has zero for all supervisor features, which does
not match the XCOMP_BV field.
As XFEATURE_MASK_FPSTATE includes supervisor features setting up the FPU
causes a #GP, which ends up in fpu_reset_from_exception_fixup(). That fails
due to the same problem resulting in recursive #GPs until the kernel runs
out of stack space and double faults.
Prevent this by storing the supported independent features in
fpu_kernel_cfg during XSTATE initialization and use that cached value for
retrieving the independent feature bits to be written into IA32_XSS.
[ tglx: Massaged change log ]
Fixes:
|
||
|
Aruna Ramakrishna
|
70044df250 |
x86/pkeys: Update PKRU to enable all pkeys before XSAVE
If the alternate signal stack is protected by a different PKEY than the current execution stack, copying XSAVE data to the sigaltstack will fail if its PKEY is not enabled in the PKRU register. It's unknown which pkey was used by the application for the altstack, so enable all PKEYS before XSAVE. But this updated PKRU value is also pushed onto the sigframe, which means the register value restored from sigcontext will be different from the user-defined one, which is incorrect. Fix that by overwriting the PKRU value on the sigframe with the original, user-defined PKRU. Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/all/20240802061318.2140081-4-aruna.ramakrishna@oracle.com |
||
|
Aruna Ramakrishna
|
84ee6e8d19 |
x86/pkeys: Add helper functions to update PKRU on the sigframe
In the case where a user thread sets up an alternate signal stack protected by the default PKEY (i.e. PKEY 0), while the thread's stack is protected by a non-zero PKEY, both these PKEYS have to be enabled in the PKRU register for the signal to be delivered to the application correctly. However, the PKRU value restored after handling the signal must not enable this extra PKEY (i.e. PKEY 0) - i.e., the PKRU value in the sigframe has to be overwritten with the user-defined value. Add helper functions that will update PKRU value in the sigframe after XSAVE. Note that sig_prepare_pkru() makes no assumption about which PKEY could be used to protect the altstack (i.e. it may not be part of init_pkru), and so enables all PKEYS. No functional change. Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/all/20240802061318.2140081-3-aruna.ramakrishna@oracle.com |
||
|
Aruna Ramakrishna
|
24cf2bc982 |
x86/pkeys: Add PKRU as a parameter in signal handling functions
Assume there's a multithreaded application that runs untrusted user
code. Each thread has its stack/code protected by a non-zero PKEY, and the
PKRU register is set up such that only that particular non-zero PKEY is
enabled. Each thread also sets up an alternate signal stack to handle
signals, which is protected by PKEY zero. The PKEYs man page documents that
the PKRU will be reset to init_pkru when the signal handler is invoked,
which means that PKEY zero access will be enabled. But this reset happens
after the kernel attempts to push fpu state to the alternate stack, which
is not (yet) accessible by the kernel, which leads to a new SIGSEGV being
sent to the application, terminating it.
Enabling both the non-zero PKEY (for the thread) and PKEY zero in
userspace will not work for this use case. It cannot have the alt stack
writeable by all - the rationale here is that the code running in that
thread (using a non-zero PKEY) is untrusted and should not have access
to the alternate signal stack (that uses PKEY zero), to prevent the
return address of a function from being changed. The expectation is that
kernel should be able to set up the alternate signal stack and deliver
the signal to the application even if PKEY zero is explicitly disabled
by the application. The signal handler accessibility should not be
dictated by whatever PKRU value the thread sets up.
The PKRU register is managed by XSAVE, which means the sigframe contents
must match the register contents - which is not the case here. It's
required that the signal frame contains the user-defined PKRU value (so
that it is restored correctly from sigcontext) but the actual register must
be reset to init_pkru so that the alt stack is accessible and the signal
can be delivered to the application. It seems that the proper fix here
would be to remove PKRU from the XSAVE framework and manage it separately,
which is quite complicated. As a workaround, do this:
orig_pkru = rdpkru();
wrpkru(orig_pkru & init_pkru_value);
xsave_to_user_sigframe();
put_user(pkru_sigframe_addr, orig_pkru)
In preparation for writing PKRU to sigframe, pass PKRU as an additional
parameter down the call chain from get_sigframe().
No functional change.
Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240802061318.2140081-2-aruna.ramakrishna@oracle.com
|
||
|
Vignesh Balasubramanian
|
ba386777a3 |
x86/elf: Add a new FPU buffer layout info to x86 core files
Add a new .note section containing type, size, offset and flags of every xfeature that is present. This information will be used by debuggers to understand the XSAVE layout of the machine where the core file has been dumped, and to read XSAVE registers, especially during cross-platform debugging. The XSAVE layouts of modern AMD and Intel CPUs differ, especially since Memory Protection Keys and the AVX-512 features have been inculcated into the AMD CPUs. Since AMD never adopted (and hence never left room in the XSAVE layout for) the Intel MPX feature, tools like GDB had assumed a fixed XSAVE layout matching that of Intel (based on the XCR0 mask). Hence, core dumps from AMD CPUs didn't match the known size for the XCR0 mask. This resulted in GDB and other tools not being able to access the values of the AVX-512 and PKRU registers on AMD CPUs. To solve this, an interim solution has been accepted into GDB, and is already a part of GDB 14, see https://sourceware.org/pipermail/gdb-patches/2023-March/198081.html. But it depends on heuristics based on the total XSAVE register set size and the XCR0 mask to infer the layouts of the various register blocks for core dumps, and hence, is not a foolproof mechanism to determine the layout of the XSAVE area. Therefore, add a new core dump note in order to allow GDB/LLDB and other relevant tools to determine the layout of the XSAVE area of the machine where the corefile was dumped. The new core dump note (which is being proposed as a per-process .note section), NT_X86_XSAVE_LAYOUT (0x205) contains an array of structures. Each structure describes an individual extended feature containing offset, size and flags in this format: struct x86_xfeat_component { u32 type; u32 size; u32 offset; u32 flags; }; and in an independent manner, allowing for future extensions without depending on hw arch specifics like CPUID etc. [ bp: Massage commit message, zap trailing whitespace. ] Co-developed-by: Jini Susan George <jinisusan.george@amd.com> Signed-off-by: Jini Susan George <jinisusan.george@amd.com> Co-developed-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Vignesh Balasubramanian <vigbalas@amd.com> Link: https://lore.kernel.org/r/20240725161017.112111-2-vigbalas@amd.com |
||
|
Borislav Petkov (AMD)
|
93694129c6 |
x86/alternative: Convert ALTERNATIVE_3()
Zap the hack of using an ALTERNATIVE_3() internal label, as suggested by bgerst: https://lore.kernel.org/r/CAMzpN2i4oJ-Dv0qO46Fd-DxNv5z9=x%2BvO%2B8g=47NiiAf8QEJYA@mail.gmail.com in favor of a label local to this macro only, as it should be done. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240607111701.8366-11-bp@kernel.org |
||
|
Linus Torvalds
|
f4b0c4b508 |
ARM:
* Move a lot of state that was previously stored on a per vcpu
basis into a per-CPU area, because it is only pertinent to the
host while the vcpu is loaded. This results in better state
tracking, and a smaller vcpu structure.
* Add full handling of the ERET/ERETAA/ERETAB instructions in
nested virtualisation. The last two instructions also require
emulating part of the pointer authentication extension.
As a result, the trap handling of pointer authentication has
been greatly simplified.
* Turn the global (and not very scalable) LPI translation cache
into a per-ITS, scalable cache, making non directly injected
LPIs much cheaper to make visible to the vcpu.
* A batch of pKVM patches, mostly fixes and cleanups, as the
upstreaming process seems to be resuming. Fingers crossed!
* Allocate PPIs and SGIs outside of the vcpu structure, allowing
for smaller EL2 mapping and some flexibility in implementing
more or less than 32 private IRQs.
* Purge stale mpidr_data if a vcpu is created after the MPIDR
map has been created.
* Preserve vcpu-specific ID registers across a vcpu reset.
* Various minor cleanups and improvements.
LoongArch:
* Add ParaVirt IPI support.
* Add software breakpoint support.
* Add mmio trace events support.
RISC-V:
* Support guest breakpoints using ebreak
* Introduce per-VCPU mp_state_lock and reset_cntx_lock
* Virtualize SBI PMU snapshot and counter overflow interrupts
* New selftests for SBI PMU and Guest ebreak
* Some preparatory work for both TDX and SNP page fault handling.
This also cleans up the page fault path, so that the priorities
of various kinds of fauls (private page, no memory, write
to read-only slot, etc.) are easier to follow.
x86:
* Minimize amount of time that shadow PTEs remain in the special
REMOVED_SPTE state. This is a state where the mmu_lock is held for
reading but concurrent accesses to the PTE have to spin; shortening
its use allows other vCPUs to repopulate the zapped region while
the zapper finishes tearing down the old, defunct page tables.
* Advertise the max mappable GPA in the "guest MAXPHYADDR" CPUID field,
which is defined by hardware but left for software use. This lets KVM
communicate its inability to map GPAs that set bits 51:48 on hosts
without 5-level nested page tables. Guest firmware is expected to
use the information when mapping BARs; this avoids that they end up at
a legal, but unmappable, GPA.
* Fixed a bug where KVM would not reject accesses to MSR that aren't
supposed to exist given the vCPU model and/or KVM configuration.
* As usual, a bunch of code cleanups.
x86 (AMD):
* Implement a new and improved API to initialize SEV and SEV-ES VMs, which
will also be extendable to SEV-SNP. The new API specifies the desired
encryption in KVM_CREATE_VM and then separately initializes the VM.
The new API also allows customizing the desired set of VMSA features;
the features affect the measurement of the VM's initial state, and
therefore enabling them cannot be done tout court by the hypervisor.
While at it, the new API includes two bugfixes that couldn't be
applied to the old one without a flag day in userspace or without
affecting the initial measurement. When a SEV-ES VM is created with
the new VM type, KVM_GET_REGS/KVM_SET_REGS and friends are
rejected once the VMSA has been encrypted. Also, the FPU and AVX
state will be synchronized and encrypted too.
* Support for GHCB version 2 as applicable to SEV-ES guests. This, once
more, is only accessible when using the new KVM_SEV_INIT2 flow for
initialization of SEV-ES VMs.
x86 (Intel):
* An initial bunch of prerequisite patches for Intel TDX were merged.
They generally don't do anything interesting. The only somewhat user
visible change is a new debugging mode that checks that KVM's MMU
never triggers a #VE virtualization exception in the guest.
* Clear vmcs.EXIT_QUALIFICATION when synthesizing an EPT Misconfig VM-Exit to
L1, as per the SDM.
Generic:
* Use vfree() instead of kvfree() for allocations that always use vcalloc()
or __vcalloc().
* Remove .change_pte() MMU notifier - the changes to non-KVM code are
small and Andrew Morton asked that I also take those through the KVM
tree. The callback was only ever implemented by KVM (which was also the
original user of MMU notifiers) but it had been nonfunctional ever since
calls to set_pte_at_notify were wrapped with invalidate_range_start
and invalidate_range_end... in 2012.
Selftests:
* Enhance the demand paging test to allow for better reporting and stressing
of UFFD performance.
* Convert the steal time test to generate TAP-friendly output.
* Fix a flaky false positive in the xen_shinfo_test due to comparing elapsed
time across two different clock domains.
* Skip the MONITOR/MWAIT test if the host doesn't actually support MWAIT.
* Avoid unnecessary use of "sudo" in the NX hugepage test wrapper shell
script, to play nice with running in a minimal userspace environment.
* Allow skipping the RSEQ test's sanity check that the vCPU was able to
complete a reasonable number of KVM_RUNs, as the assert can fail on a
completely valid setup. If the test is run on a large-ish system that is
otherwise idle, and the test isn't affined to a low-ish number of CPUs, the
vCPU task can be repeatedly migrated to CPUs that are in deep sleep states,
which results in the vCPU having very little net runtime before the next
migration due to high wakeup latencies.
* Define _GNU_SOURCE for all selftests to fix a warning that was introduced by
a change to kselftest_harness.h late in the 6.9 cycle, and because forcing
every test to #define _GNU_SOURCE is painful.
* Provide a global pseudo-RNG instance for all tests, so that library code can
generate random, but determinstic numbers.
* Use the global pRNG to randomly force emulation of select writes from guest
code on x86, e.g. to help validate KVM's emulation of locked accesses.
* Allocate and initialize x86's GDT, IDT, TSS, segments, and default exception
handlers at VM creation, instead of forcing tests to manually trigger the
related setup.
Documentation:
* Fix a goof in the KVM_CREATE_GUEST_MEMFD documentation.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
"ARM:
- Move a lot of state that was previously stored on a per vcpu basis
into a per-CPU area, because it is only pertinent to the host while
the vcpu is loaded. This results in better state tracking, and a
smaller vcpu structure.
- Add full handling of the ERET/ERETAA/ERETAB instructions in nested
virtualisation. The last two instructions also require emulating
part of the pointer authentication extension. As a result, the trap
handling of pointer authentication has been greatly simplified.
- Turn the global (and not very scalable) LPI translation cache into
a per-ITS, scalable cache, making non directly injected LPIs much
cheaper to make visible to the vcpu.
- A batch of pKVM patches, mostly fixes and cleanups, as the
upstreaming process seems to be resuming. Fingers crossed!
- Allocate PPIs and SGIs outside of the vcpu structure, allowing for
smaller EL2 mapping and some flexibility in implementing more or
less than 32 private IRQs.
- Purge stale mpidr_data if a vcpu is created after the MPIDR map has
been created.
- Preserve vcpu-specific ID registers across a vcpu reset.
- Various minor cleanups and improvements.
LoongArch:
- Add ParaVirt IPI support
- Add software breakpoint support
- Add mmio trace events support
RISC-V:
- Support guest breakpoints using ebreak
- Introduce per-VCPU mp_state_lock and reset_cntx_lock
- Virtualize SBI PMU snapshot and counter overflow interrupts
- New selftests for SBI PMU and Guest ebreak
- Some preparatory work for both TDX and SNP page fault handling.
This also cleans up the page fault path, so that the priorities of
various kinds of fauls (private page, no memory, write to read-only
slot, etc.) are easier to follow.
x86:
- Minimize amount of time that shadow PTEs remain in the special
REMOVED_SPTE state.
This is a state where the mmu_lock is held for reading but
concurrent accesses to the PTE have to spin; shortening its use
allows other vCPUs to repopulate the zapped region while the zapper
finishes tearing down the old, defunct page tables.
- Advertise the max mappable GPA in the "guest MAXPHYADDR" CPUID
field, which is defined by hardware but left for software use.
This lets KVM communicate its inability to map GPAs that set bits
51:48 on hosts without 5-level nested page tables. Guest firmware
is expected to use the information when mapping BARs; this avoids
that they end up at a legal, but unmappable, GPA.
- Fixed a bug where KVM would not reject accesses to MSR that aren't
supposed to exist given the vCPU model and/or KVM configuration.
- As usual, a bunch of code cleanups.
x86 (AMD):
- Implement a new and improved API to initialize SEV and SEV-ES VMs,
which will also be extendable to SEV-SNP.
The new API specifies the desired encryption in KVM_CREATE_VM and
then separately initializes the VM. The new API also allows
customizing the desired set of VMSA features; the features affect
the measurement of the VM's initial state, and therefore enabling
them cannot be done tout court by the hypervisor.
While at it, the new API includes two bugfixes that couldn't be
applied to the old one without a flag day in userspace or without
affecting the initial measurement. When a SEV-ES VM is created with
the new VM type, KVM_GET_REGS/KVM_SET_REGS and friends are rejected
once the VMSA has been encrypted. Also, the FPU and AVX state will
be synchronized and encrypted too.
- Support for GHCB version 2 as applicable to SEV-ES guests.
This, once more, is only accessible when using the new
KVM_SEV_INIT2 flow for initialization of SEV-ES VMs.
x86 (Intel):
- An initial bunch of prerequisite patches for Intel TDX were merged.
They generally don't do anything interesting. The only somewhat
user visible change is a new debugging mode that checks that KVM's
MMU never triggers a #VE virtualization exception in the guest.
- Clear vmcs.EXIT_QUALIFICATION when synthesizing an EPT Misconfig
VM-Exit to L1, as per the SDM.
Generic:
- Use vfree() instead of kvfree() for allocations that always use
vcalloc() or __vcalloc().
- Remove .change_pte() MMU notifier - the changes to non-KVM code are
small and Andrew Morton asked that I also take those through the
KVM tree.
The callback was only ever implemented by KVM (which was also the
original user of MMU notifiers) but it had been nonfunctional ever
since calls to set_pte_at_notify were wrapped with
invalidate_range_start and invalidate_range_end... in 2012.
Selftests:
- Enhance the demand paging test to allow for better reporting and
stressing of UFFD performance.
- Convert the steal time test to generate TAP-friendly output.
- Fix a flaky false positive in the xen_shinfo_test due to comparing
elapsed time across two different clock domains.
- Skip the MONITOR/MWAIT test if the host doesn't actually support
MWAIT.
- Avoid unnecessary use of "sudo" in the NX hugepage test wrapper
shell script, to play nice with running in a minimal userspace
environment.
- Allow skipping the RSEQ test's sanity check that the vCPU was able
to complete a reasonable number of KVM_RUNs, as the assert can fail
on a completely valid setup.
If the test is run on a large-ish system that is otherwise idle,
and the test isn't affined to a low-ish number of CPUs, the vCPU
task can be repeatedly migrated to CPUs that are in deep sleep
states, which results in the vCPU having very little net runtime
before the next migration due to high wakeup latencies.
- Define _GNU_SOURCE for all selftests to fix a warning that was
introduced by a change to kselftest_harness.h late in the 6.9
cycle, and because forcing every test to #define _GNU_SOURCE is
painful.
- Provide a global pseudo-RNG instance for all tests, so that library
code can generate random, but determinstic numbers.
- Use the global pRNG to randomly force emulation of select writes
from guest code on x86, e.g. to help validate KVM's emulation of
locked accesses.
- Allocate and initialize x86's GDT, IDT, TSS, segments, and default
exception handlers at VM creation, instead of forcing tests to
manually trigger the related setup.
Documentation:
- Fix a goof in the KVM_CREATE_GUEST_MEMFD documentation"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (225 commits)
selftests/kvm: remove dead file
KVM: selftests: arm64: Test vCPU-scoped feature ID registers
KVM: selftests: arm64: Test that feature ID regs survive a reset
KVM: selftests: arm64: Store expected register value in set_id_regs
KVM: selftests: arm64: Rename helper in set_id_regs to imply VM scope
KVM: arm64: Only reset vCPU-scoped feature ID regs once
KVM: arm64: Reset VM feature ID regs from kvm_reset_sys_regs()
KVM: arm64: Rename is_id_reg() to imply VM scope
KVM: arm64: Destroy mpidr_data for 'late' vCPU creation
KVM: arm64: Use hVHE in pKVM by default on CPUs with VHE support
KVM: arm64: Fix hvhe/nvhe early alias parsing
KVM: SEV: Allow per-guest configuration of GHCB protocol version
KVM: SEV: Add GHCB handling for termination requests
KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests
KVM: SEV: Add support to handle AP reset MSR protocol
KVM: x86: Explicitly zero kvm_caps during vendor module load
KVM: x86: Fully re-initialize supported_mce_cap on vendor module load
KVM: x86: Fully re-initialize supported_vm_types on vendor module load
KVM: x86/mmu: Sanity check that __kvm_faultin_pfn() doesn't create noslot pfns
KVM: x86/mmu: Initialize kvm_page_fault's pfn and hva to error values
...
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Linus Torvalds
|
963795f758 |
x86/fpu changes for v6.10:
- Fix asm() constraints & modifiers in restore_fpregs_from_fpstate() - Update comments - Robustify the free_vm86() definition Signed-off-by: Ingo Molnar <mingo@kernel.org> -----BEGIN PGP SIGNATURE----- iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmZBw6ARHG1pbmdvQGtl cm5lbC5vcmcACgkQEnMQ0APhK1h66w/+MBZiDW9BdUaMArOO3F2epa+E/SFmcaSO KxLvs9A606nV+qW2RhHZjYcdl5oOAF0yRyofxbVLluYPt7z8GPUIrVKPHq7BD3Es amzaD0Rq00qPa+jwrt8qsOddz2KglAkgYZJcukf5hBZ6/VfiKfDeRG3D7nTyabVp sYwM7POmB5dkBrOTdmp6ikliNvmp8tfh6AiSM3NgQ8uq0YN7tm7f5iFSulBfrRN3 Y2x6LEXOuSSEzEIO/7ju4maE6JunqWMkRWWb5yyUZKZKG69dunp4LZr5kAfi/7jV SZRO16YOZOsl5XBp4QlDv2p5xM/XD3uM8UhUSlMYL0+6i/wpEMnJpcSaffLv5wNG I6RxG8d/G1hpsUoW8ClLTWfppL450z31lmwatLa1ctnuGppcx3oxEA+vBTo3I89c fVMHvDvTs7iau2K9mmpZzhLLglnf7ZDTclyVsPrECQtB+grFHL8DNKea4nn4VInH LO9XBbckuM1ZjJt1KzGNWZbpxRBRpnNVjyyYPodD4el9IyglXzcvVNR0SGCtXB+3 Td7/RBkBmNadefckOJaT1VEGXlKOlOAKtWB+A17jpzCSoaKSzhXw/khbxIG3oYOv BRulU9r16rDzuMiDLjfFHpC4BhjDSluDuFS1Xtg+P3PZQR+LDn9msJaWFWL7pexK xhs5daRBrqs= =PO9v -----END PGP SIGNATURE----- Merge tag 'x86-fpu-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fpu updates from Ingo Molnar: - Fix asm() constraints & modifiers in restore_fpregs_from_fpstate() - Update comments - Robustify the free_vm86() definition * tag 'x86-fpu-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fpu: Update fpu_swap_kvm_fpu() uses in comments as well x86/vm86: Make sure the free_vm86(task) definition uses its parameter even in the !CONFIG_VM86 case x86/fpu: Fix AMD X86_BUG_FXSAVE_LEAK fixup |
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Paolo Bonzini
|
eb4441864e |
KVM: SEV: sync FPU and AVX state at LAUNCH_UPDATE_VMSA time
SEV-ES allows passing custom contents for x87, SSE and AVX state into the VMSA. Allow userspace to do that with the usual KVM_SET_XSAVE API and only mark FPU contents as confidential after it has been copied and encrypted into the VMSA. Since the XSAVE state for AVX is the first, it does not need the compacted-state handling of get_xsave_addr(). However, there are other parts of XSAVE state in the VMSA that currently are not handled, and the validation logic of get_xsave_addr() is pointless to duplicate in KVM, so move get_xsave_addr() to public FPU API; it is really just a facility to operate on XSAVE state and does not expose any internal details of arch/x86/kernel/fpu. Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-ID: <20240404121327.3107131-12-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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Li RongQing
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af813acf8c |
x86/fpu: Update fpu_swap_kvm_fpu() uses in comments as well
The following commit:
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Adamos Ttofari
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10e4b5166d |
x86/fpu: Keep xfd_state in sync with MSR_IA32_XFD
Commit |
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Uros Bizjak
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5d31174f3c |
x86/fpu: Fix AMD X86_BUG_FXSAVE_LEAK fixup
The assembly snippet in restore_fpregs_from_fpstate() that implements
X86_BUG_FXSAVE_LEAK fixup loads the value from a random variable,
preferably the one that is already in the L1 cache.
However, the access to fpinit_state via *fpstate pointer is not
implemented correctly. The "m" asm constraint requires dereferenced
pointer variable, otherwise the compiler just reloads the value
via temporary stack slot. The current asm code reflects this:
mov %rdi,(%rsp)
...
fildl (%rsp)
With dereferenced pointer variable, the code does what the
comment above the asm snippet says:
fildl (%rdi)
Also, remove the pointless %P operand modifier. The modifier is
ineffective on non-symbolic references - it was used to prevent
%rip-relative addresses in .altinstr sections, but FILDL in the
.text section can use %rip-relative addresses without problems.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240315081849.5187-1-ubizjak@gmail.com
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Thomas Gleixner
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154fcf3a78 |
x86/msr: Prepare for including <linux/percpu.h> into <asm/msr.h>
To clean up the per CPU insanity of UP which causes sparse to be rightfully unhappy and prevents the usage of the generic per CPU accessors on cpu_info it is necessary to include <linux/percpu.h> into <asm/msr.h>. Including <linux/percpu.h> into <asm/msr.h> is impossible because it ends up in header dependency hell. The problem is that <asm/processor.h> includes <asm/msr.h>. The inclusion of <linux/percpu.h> results in a compile fail where the compiler cannot longer handle an include in <asm/cpufeature.h> which references boot_cpu_data which is defined in <asm/processor.h>. The only reason why <asm/msr.h> is included in <asm/processor.h> are the set/get_debugctlmsr() inlines. They are defined there because <asm/processor.h> is such a nice dump ground for everything. In fact they belong obviously into <asm/debugreg.h>. Move them to <asm/debugreg.h> and fix up the resulting damage which is just exposing the reliance on random include chains. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20240304005104.454678686@linutronix.de |
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Andrei Vagin
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d877550eaf |
x86/fpu: Stop relying on userspace for info to fault in xsave buffer
Before this change, the expected size of the user space buffer was
taken from fx_sw->xstate_size. fx_sw->xstate_size can be changed
from user-space, so it is possible construct a sigreturn frame where:
* fx_sw->xstate_size is smaller than the size required by valid bits in
fx_sw->xfeatures.
* user-space unmaps parts of the sigrame fpu buffer so that not all of
the buffer required by xrstor is accessible.
In this case, xrstor tries to restore and accesses the unmapped area
which results in a fault. But fault_in_readable succeeds because buf +
fx_sw->xstate_size is within the still mapped area, so it goes back and
tries xrstor again. It will spin in this loop forever.
Instead, fault in the maximum size which can be touched by XRSTOR (taken
from fpstate->user_size).
[ dhansen: tweak subject / changelog ]
Fixes:
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Linus Torvalds
|
78273df7f6 |
header cleanups for 6.8
The goal is to get sched.h down to a type only header, so the main thing happening in this patchset is splitting out various _types.h headers and dependency fixups, as well as moving some things out of sched.h to better locations. This is prep work for the memory allocation profiling patchset which adds new sched.h interdepencencies. Testing - it's been in -next, and fixes from pretty much all architectures have percolated in - nothing major. -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEKnAFLkS8Qha+jvQrE6szbY3KbnYFAmWfBwwACgkQE6szbY3K bnZPwBAAmuRojXaeWxi01IPIOehSGDe68vw44PR9glEMZvxdnZuPOdvE4/+245/L bRKU2WBCjBUokUbV9msIShwRkFTZAmEMPNfPAAsFMA+VXeDYHKB+ZRdwTggNAQ+I SG6fZgh5m0HsewCDxU8oqVHkjVq4fXn0cy+aL6xLEd9gu67GoBzX2pDieS2Kvy6j jnyoKTxFwb+LTQgph0P4EIpq5I2umAsdLwdSR8EJ+8e9NiNvMo1pI00Lx/ntAnFZ JftWUJcMy3TQ5u1GkyfQN9y/yThX1bZK5GvmHS9SJ2Dkacaus5d+xaKCHtRuFS1I 7C6b8PsNgRczUMumBXus44HdlNfNs1yU3lvVxFvBIPE1qC9pYRHrkWIXXIocXLLC oxTEJ6B2G3BQZVQgLIA4fOaxMVhmvKffi/aEZLi9vN9VVosd1a6XNKI6KbyRnXFp GSs9qDqszhn5I3GYNlDNQTc/8UsRlhPFgS6nS0By6QnvxtGi9QkU2tBRBsXvqwCy cLoCYIhc2tvugHvld70dz26umiJ4rnmxGlobStNoigDvIKAIUt1UmIdr1so8P8eH xehnL9ZcOX6xnANDL0AqMFFHV6I58CJynhFdUoXfVQf/DWLGX48mpi9LVNsYBzsI CAwVOAQ0UjGrpdWmJ9ueY/ABYqg9vRjzaDEXQ+MhAYO55CLaVsg= =3tyT -----END PGP SIGNATURE----- Merge tag 'header_cleanup-2024-01-10' of https://evilpiepirate.org/git/bcachefs Pull header cleanups from Kent Overstreet: "The goal is to get sched.h down to a type only header, so the main thing happening in this patchset is splitting out various _types.h headers and dependency fixups, as well as moving some things out of sched.h to better locations. This is prep work for the memory allocation profiling patchset which adds new sched.h interdepencencies" * tag 'header_cleanup-2024-01-10' of https://evilpiepirate.org/git/bcachefs: (51 commits) Kill sched.h dependency on rcupdate.h kill unnecessary thread_info.h include Kill unnecessary kernel.h include preempt.h: Kill dependency on list.h rseq: Split out rseq.h from sched.h LoongArch: signal.c: add header file to fix build error restart_block: Trim includes lockdep: move held_lock to lockdep_types.h sem: Split out sem_types.h uidgid: Split out uidgid_types.h seccomp: Split out seccomp_types.h refcount: Split out refcount_types.h uapi/linux/resource.h: fix include x86/signal: kill dependency on time.h syscall_user_dispatch.h: split out *_types.h mm_types_task.h: Trim dependencies Split out irqflags_types.h ipc: Kill bogus dependency on spinlock.h shm: Slim down dependencies workqueue: Split out workqueue_types.h ... |
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Bjorn Helgaas
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54aa699e80 |
arch/x86: Fix typos
Fix typos, most reported by "codespell arch/x86". Only touches comments, no code changes. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Link: https://lore.kernel.org/r/20240103004011.1758650-1-helgaas@kernel.org |
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Kent Overstreet
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a5a0abfdb3 |
x86: fix missing includes/forward declarations
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> |
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Linus Torvalds
|
9cda4eb04a |
- A kernel-doc fix
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Sean Christopherson
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8647c52e95 |
KVM: x86: Constrain guest-supported xfeatures only at KVM_GET_XSAVE{2}
Mask off xfeatures that aren't exposed to the guest only when saving guest
state via KVM_GET_XSAVE{2} instead of modifying user_xfeatures directly.
Preserving the maximal set of xfeatures in user_xfeatures restores KVM's
ABI for KVM_SET_XSAVE, which prior to commit
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Sean Christopherson
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18164f66e6 |
x86/fpu: Allow caller to constrain xfeatures when copying to uabi buffer
Plumb an xfeatures mask into __copy_xstate_to_uabi_buf() so that KVM can
constrain which xfeatures are saved into the userspace buffer without
having to modify the user_xfeatures field in KVM's guest_fpu state.
KVM's ABI for KVM_GET_XSAVE{2} is that features that are not exposed to
guest must not show up in the effective xstate_bv field of the buffer.
Saving only the guest-supported xfeatures allows userspace to load the
saved state on a different host with a fewer xfeatures, so long as the
target host supports the xfeatures that are exposed to the guest.
KVM currently sets user_xfeatures directly to restrict KVM_GET_XSAVE{2} to
the set of guest-supported xfeatures, but doing so broke KVM's historical
ABI for KVM_SET_XSAVE, which allows userspace to load any xfeatures that
are supported by the *host*.
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230928001956.924301-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Zhu Wang
|
90879f5dfc |
x86/fpu/xstate: Address kernel-doc warning
Fix kernel-doc warning: arch/x86/kernel/fpu/xstate.c:1753: warning: Excess function parameter 'tsk' description in 'fpu_xstate_prctl' Signed-off-by: Zhu Wang <wangzhu9@huawei.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: linux-kernel@vger.kernel.org |
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Linus Torvalds
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2fcbb03847 |
* Mark all Skylake CPUs as vulnerable to GDS
* Fix PKRU covert channel * Fix -Wmissing-variable-declarations warning for ia32_xyz_class * Fix kernel-doc annotation warning -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEV76QKkVc4xCGURexaDWVMHDJkrAFAmTyK2sACgkQaDWVMHDJ krCPyA//WbT65hhGZt5UHayoW3Cv8NmS4kRf6FTVMmt1yIvbOtVmWVZeOGMypprC jYBPOdTf1SdoUxeD1cTTd/rtbYknczaBLC5VGilGb2/663yQl9ThT3ePc6OgUpPW 28ItLslfHGchHbrOgCgUK8Aiv8xRdfNUJoByMTOoce6eGUQsgYaNOq74z1YaLsZ4 afbitcd/vWO9eJfW5DNl26rIP+ksOgA/Iue8uRiEczoPltnbUxGGLCtuuR9B2Xxi FqfttvcnUy9yFJBnELx4721VtTcmK4Dq5O/ZoJnmVQqRPY9aXpkbwZnH9co8r/uh GueQj30l6VhEO6XnwPvjsOghXI2vOMrxlL3zGMw5y6pjfUWa4W6f33EV6mByYfml dfPTXIz9K1QxznHtk6xVhn1X8CFw7L1L7CC/2CPQPETiuqyjWrHqvFBXcsWpKq4N 1GjnpoveNZmWcE7UY9qEHAXGh7ndI+EIux/0WfJJHOE/fzCr06GphQdxNwPGdi5O T3JkZf6R4GBvfi6e0F6Qn2B02sDl18remmAMi9bAn/M31g+mvAoHqKLlI9EzAGGz 91PzJdHecdvalU6zsCKqi0ETzq11WG7zCfSXs+jeHBe1jsUITpcZCkpVi2pGA2aq X7qLjJyW+Sx0hdE2IWFhCOfiwGFpXxfegCl1uax3HrZg6rrORbw= =prt2 -----END PGP SIGNATURE----- Merge tag 'x86-urgent-2023-09-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixes from Dave Hansen: "The most important fix here adds a missing CPU model to the recent Gather Data Sampling (GDS) mitigation list to ensure that mitigations are available on that CPU. There are also a pair of warning fixes, and closure of a covert channel that pops up when protection keys are disabled. Summary: - Mark all Skylake CPUs as vulnerable to GDS - Fix PKRU covert channel - Fix -Wmissing-variable-declarations warning for ia32_xyz_class - Fix kernel-doc annotation warning" * tag 'x86-urgent-2023-09-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fpu/xstate: Fix PKRU covert channel x86/irq/i8259: Fix kernel-doc annotation warning x86/speculation: Mark all Skylake CPUs as vulnerable to GDS x86/audit: Fix -Wmissing-variable-declarations warning for ia32_xyz_class |
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Jim Mattson
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18032b47ad |
x86/fpu/xstate: Fix PKRU covert channel
When XCR0[9] is set, PKRU can be read and written from userspace with XSAVE and XRSTOR, even when CR4.PKE is clear. Clear XCR0[9] when protection keys are disabled. Reported-by: Tavis Ormandy <taviso@google.com> Signed-off-by: Jim Mattson <jmattson@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/r/20230831043228.1194256-1-jmattson@google.com |
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Linus Torvalds
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df57721f9a |
Add x86 shadow stack support
Convert IBT selftest to asm to fix objtool warning -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEV76QKkVc4xCGURexaDWVMHDJkrAFAmTv1QQACgkQaDWVMHDJ krAUwhAAn6TOwHJK8BSkHeiQhON1nrlP3c5cv0AyZ2NP8RYDrZrSZvhpYBJ6wgKC Cx5CGq5nn9twYsYS3KsktLKDfR3lRdsQ7K9qtyFtYiaeaVKo+7gEKl/K+klwai8/ gninQWHk0zmSCja8Vi77q52WOMkQKapT8+vaON9EVDO8dVEi+CvhAIfPwMafuiwO Rk4X86SzoZu9FP79LcCg9XyGC/XbM2OG9eNUTSCKT40qTTKm5y4gix687NvAlaHR ko5MTsdl0Wfp6Qk0ohT74LnoA2c1g/FluvZIM33ci/2rFpkf9Hw7ip3lUXqn6CPx rKiZ+pVRc0xikVWkraMfIGMJfUd2rhelp8OyoozD7DB7UZw40Q4RW4N5tgq9Fhe9 MQs3p1v9N8xHdRKl365UcOczUxNAmv4u0nV5gY/4FMC6VjldCl2V9fmqYXyzFS4/ Ogg4FSd7c2JyGFKPs+5uXyi+RY2qOX4+nzHOoKD7SY616IYqtgKoz5usxETLwZ6s VtJOmJL0h//z0A7tBliB0zd+SQ5UQQBDC2XouQH2fNX2isJMn0UDmWJGjaHgK6Hh 8jVp6LNqf+CEQS387UxckOyj7fu438hDky1Ggaw4YqowEOhQeqLVO4++x+HITrbp AupXfbJw9h9cMN63Yc0gVxXQ9IMZ+M7UxLtZ3Cd8/PVztNy/clA= =3UUm -----END PGP SIGNATURE----- Merge tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 shadow stack support from Dave Hansen: "This is the long awaited x86 shadow stack support, part of Intel's Control-flow Enforcement Technology (CET). CET consists of two related security features: shadow stacks and indirect branch tracking. This series implements just the shadow stack part of this feature, and just for userspace. The main use case for shadow stack is providing protection against return oriented programming attacks. It works by maintaining a secondary (shadow) stack using a special memory type that has protections against modification. When executing a CALL instruction, the processor pushes the return address to both the normal stack and to the special permission shadow stack. Upon RET, the processor pops the shadow stack copy and compares it to the normal stack copy. For more information, refer to the links below for the earlier versions of this patch set" Link: https://lore.kernel.org/lkml/20220130211838.8382-1-rick.p.edgecombe@intel.com/ Link: https://lore.kernel.org/lkml/20230613001108.3040476-1-rick.p.edgecombe@intel.com/ * tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (47 commits) x86/shstk: Change order of __user in type x86/ibt: Convert IBT selftest to asm x86/shstk: Don't retry vm_munmap() on -EINTR x86/kbuild: Fix Documentation/ reference x86/shstk: Move arch detail comment out of core mm x86/shstk: Add ARCH_SHSTK_STATUS x86/shstk: Add ARCH_SHSTK_UNLOCK x86: Add PTRACE interface for shadow stack selftests/x86: Add shadow stack test x86/cpufeatures: Enable CET CR4 bit for shadow stack x86/shstk: Wire in shadow stack interface x86: Expose thread features in /proc/$PID/status x86/shstk: Support WRSS for userspace x86/shstk: Introduce map_shadow_stack syscall x86/shstk: Check that signal frame is shadow stack mem x86/shstk: Check that SSP is aligned on sigreturn x86/shstk: Handle signals for shadow stack x86/shstk: Introduce routines modifying shstk x86/shstk: Handle thread shadow stack x86/shstk: Add user-mode shadow stack support ... |
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Feng Tang
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2c66ca3949 |
x86/fpu: Set X86_FEATURE_OSXSAVE feature after enabling OSXSAVE in CR4
0-Day found a 34.6% regression in stress-ng's 'af-alg' test case, and bisected it to commit |
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Rick Edgecombe
|
1f69383b20 |
x86/fpu: Invalidate FPU state correctly on exec()
The thread flag TIF_NEED_FPU_LOAD indicates that the FPU saved state is
valid and should be reloaded when returning to userspace. However, the
kernel will skip doing this if the FPU registers are already valid as
determined by fpregs_state_valid(). The logic embedded there considers
the state valid if two cases are both true:
1: fpu_fpregs_owner_ctx points to the current tasks FPU state
2: the last CPU the registers were live in was the current CPU.
This is usually correct logic. A CPU’s fpu_fpregs_owner_ctx is set to
the current FPU during the fpregs_restore_userregs() operation, so it
indicates that the registers have been restored on this CPU. But this
alone doesn’t preclude that the task hasn’t been rescheduled to a
different CPU, where the registers were modified, and then back to the
current CPU. To verify that this was not the case the logic relies on the
second condition. So the assumption is that if the registers have been
restored, AND they haven’t had the chance to be modified (by being
loaded on another CPU), then they MUST be valid on the current CPU.
Besides the lazy FPU optimizations, the other cases where the FPU
registers might not be valid are when the kernel modifies the FPU register
state or the FPU saved buffer. In this case the operation modifying the
FPU state needs to let the kernel know the correspondence has been
broken. The comment in “arch/x86/kernel/fpu/context.h” has:
/*
...
* If the FPU register state is valid, the kernel can skip restoring the
* FPU state from memory.
*
* Any code that clobbers the FPU registers or updates the in-memory
* FPU state for a task MUST let the rest of the kernel know that the
* FPU registers are no longer valid for this task.
*
* Either one of these invalidation functions is enough. Invalidate
* a resource you control: CPU if using the CPU for something else
* (with preemption disabled), FPU for the current task, or a task that
* is prevented from running by the current task.
*/
However, this is not completely true. When the kernel modifies the
registers or saved FPU state, it can only rely on
__fpu_invalidate_fpregs_state(), which wipes the FPU’s last_cpu
tracking. The exec path instead relies on fpregs_deactivate(), which sets
the CPU’s FPU context to NULL. This was observed to fail to restore the
reset FPU state to the registers when returning to userspace in the
following scenario:
1. A task is executing in userspace on CPU0
- CPU0’s FPU context points to tasks
- fpu->last_cpu=CPU0
2. The task exec()’s
3. While in the kernel the task is preempted
- CPU0 gets a thread executing in the kernel (such that no other
FPU context is activated)
- Scheduler sets task’s fpu->last_cpu=CPU0 when scheduling out
4. Task is migrated to CPU1
5. Continuing the exec(), the task gets to
fpu_flush_thread()->fpu_reset_fpregs()
- Sets CPU1’s fpu context to NULL
- Copies the init state to the task’s FPU buffer
- Sets TIF_NEED_FPU_LOAD on the task
6. The task reschedules back to CPU0 before completing the exec() and
returning to userspace
- During the reschedule, scheduler finds TIF_NEED_FPU_LOAD is set
- Skips saving the registers and updating task’s fpu→last_cpu,
because TIF_NEED_FPU_LOAD is the canonical source.
7. Now CPU0’s FPU context is still pointing to the task’s, and
fpu->last_cpu is still CPU0. So fpregs_state_valid() returns true even
though the reset FPU state has not been restored.
So the root cause is that exec() is doing the wrong kind of invalidate. It
should reset fpu->last_cpu via __fpu_invalidate_fpregs_state(). Further,
fpu__drop() doesn't really seem appropriate as the task (and FPU) are not
going away, they are just getting reset as part of an exec. So switch to
__fpu_invalidate_fpregs_state().
Also, delete the misleading comment that says that either kind of
invalidate will be enough, because it’s not always the case.
Fixes:
|
||
|
Rick Edgecombe
|
2fab02b25a |
x86: Add PTRACE interface for shadow stack
Some applications (like GDB) would like to tweak shadow stack state via ptrace. This allows for existing functionality to continue to work for seized shadow stack applications. Provide a regset interface for manipulating the shadow stack pointer (SSP). There is already ptrace functionality for accessing xstate, but this does not include supervisor xfeatures. So there is not a completely clear place for where to put the shadow stack state. Adding it to the user xfeatures regset would complicate that code, as it currently shares logic with signals which should not have supervisor features. Don't add a general supervisor xfeature regset like the user one, because it is better to maintain flexibility for other supervisor xfeatures to define their own interface. For example, an xfeature may decide not to expose all of it's state to userspace, as is actually the case for shadow stack ptrace functionality. A lot of enum values remain to be used, so just put it in dedicated shadow stack regset. The only downside to not having a generic supervisor xfeature regset, is that apps need to be enlightened of any new supervisor xfeature exposed this way (i.e. they can't try to have generic save/restore logic). But maybe that is a good thing, because they have to think through each new xfeature instead of encountering issues when a new supervisor xfeature was added. By adding a shadow stack regset, it also has the effect of including the shadow stack state in a core dump, which could be useful for debugging. The shadow stack specific xstate includes the SSP, and the shadow stack and WRSS enablement status. Enabling shadow stack or WRSS in the kernel involves more than just flipping the bit. The kernel is made aware that it has to do extra things when cloning or handling signals. That logic is triggered off of separate feature enablement state kept in the task struct. So the flipping on HW shadow stack enforcement without notifying the kernel to change its behavior would severely limit what an application could do without crashing, and the results would depend on kernel internal implementation details. There is also no known use for controlling this state via ptrace today. So only expose the SSP, which is something that userspace already has indirect control over. Co-developed-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Tested-by: Pengfei Xu <pengfei.xu@intel.com> Tested-by: John Allen <john.allen@amd.com> Tested-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/all/20230613001108.3040476-41-rick.p.edgecombe%40intel.com |
||
|
Rick Edgecombe
|
b2926a36b9 |
x86/shstk: Handle thread shadow stack
When a process is duplicated, but the child shares the address space with the parent, there is potential for the threads sharing a single stack to cause conflicts for each other. In the normal non-CET case this is handled in two ways. With regular CLONE_VM a new stack is provided by userspace such that the parent and child have different stacks. For vfork, the parent is suspended until the child exits. So as long as the child doesn't return from the vfork()/CLONE_VFORK calling function and sticks to a limited set of operations, the parent and child can share the same stack. For shadow stack, these scenarios present similar sharing problems. For the CLONE_VM case, the child and the parent must have separate shadow stacks. Instead of changing clone to take a shadow stack, have the kernel just allocate one and switch to it. Use stack_size passed from clone3() syscall for thread shadow stack size. A compat-mode thread shadow stack size is further reduced to 1/4. This allows more threads to run in a 32-bit address space. The clone() does not pass stack_size, which was added to clone3(). In that case, use RLIMIT_STACK size and cap to 4 GB. For shadow stack enabled vfork(), the parent and child can share the same shadow stack, like they can share a normal stack. Since the parent is suspended until the child terminates, the child will not interfere with the parent while executing as long as it doesn't return from the vfork() and overwrite up the shadow stack. The child can safely overwrite down the shadow stack, as the parent can just overwrite this later. So CET does not add any additional limitations for vfork(). Free the shadow stack on thread exit by doing it in mm_release(). Skip this when exiting a vfork() child since the stack is shared in the parent. During this operation, the shadow stack pointer of the new thread needs to be updated to point to the newly allocated shadow stack. Since the ability to do this is confined to the FPU subsystem, change fpu_clone() to take the new shadow stack pointer, and update it internally inside the FPU subsystem. This part was suggested by Thomas Gleixner. Co-developed-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Tested-by: Pengfei Xu <pengfei.xu@intel.com> Tested-by: John Allen <john.allen@amd.com> Tested-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/all/20230613001108.3040476-30-rick.p.edgecombe%40intel.com |
||
|
Rick Edgecombe
|
6ee836687a |
x86/fpu: Add helper for modifying xstate
Just like user xfeatures, supervisor xfeatures can be active in the registers or present in the task FPU buffer. If the registers are active, the registers can be modified directly. If the registers are not active, the modification must be performed on the task FPU buffer. When the state is not active, the kernel could perform modifications directly to the buffer. But in order for it to do that, it needs to know where in the buffer the specific state it wants to modify is located. Doing this is not robust against optimizations that compact the FPU buffer, as each access would require computing where in the buffer it is. The easiest way to modify supervisor xfeature data is to force restore the registers and write directly to the MSRs. Often times this is just fine anyway as the registers need to be restored before returning to userspace. Do this for now, leaving buffer writing optimizations for the future. Add a new function fpregs_lock_and_load() that can simultaneously call fpregs_lock() and do this restore. Also perform some extra sanity checks in this function since this will be used in non-fpu focused code. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Tested-by: Pengfei Xu <pengfei.xu@intel.com> Tested-by: John Allen <john.allen@amd.com> Tested-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/all/20230613001108.3040476-26-rick.p.edgecombe%40intel.com |
||
|
Rick Edgecombe
|
8970ef027b |
x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states
Shadow stack register state can be managed with XSAVE. The registers
can logically be separated into two groups:
* Registers controlling user-mode operation
* Registers controlling kernel-mode operation
The architecture has two new XSAVE state components: one for each group
of those groups of registers. This lets an OS manage them separately if
it chooses. Future patches for host userspace and KVM guests will only
utilize the user-mode registers, so only configure XSAVE to save
user-mode registers. This state will add 16 bytes to the xsave buffer
size.
Future patches will use the user-mode XSAVE area to save guest user-mode
CET state. However, VMCS includes new fields for guest CET supervisor
states. KVM can use these to save and restore guest supervisor state, so
host supervisor XSAVE support is not required.
Adding this exacerbates the already unwieldy if statement in
check_xstate_against_struct() that handles warning about unimplemented
xfeatures. So refactor these check's by having XCHECK_SZ() set a bool when
it actually check's the xfeature. This ends up exceeding 80 chars, but was
better on balance than other options explored. Pass the bool as pointer to
make it clear that XCHECK_SZ() can change the variable.
While configuring user-mode XSAVE, clarify kernel-mode registers are not
managed by XSAVE by defining the xfeature in
XFEATURE_MASK_SUPERVISOR_UNSUPPORTED, like is done for XFEATURE_MASK_PT.
This serves more of a documentation as code purpose, and functionally,
only enables a few safety checks.
Both XSAVE state components are supervisor states, even the state
controlling user-mode operation. This is a departure from earlier features
like protection keys where the PKRU state is a normal user
(non-supervisor) state. Having the user state be supervisor-managed
ensures there is no direct, unprivileged access to it, making it harder
for an attacker to subvert CET.
To facilitate this privileged access, define the two user-mode CET MSRs,
and the bits defined in those MSRs relevant to future shadow stack
enablement patches.
Co-developed-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/all/20230613001108.3040476-25-rick.p.edgecombe%40intel.com
|
||
|
Linus Torvalds
|
7cffdbe360 |
Updates for the x86 boot process:
- Initialize FPU late.
Right now FPU is initialized very early during boot. There is no real
requirement to do so. The only requirement is to have it done before
alternatives are patched.
That's done in check_bugs() which does way more than what the function
name suggests.
So first rename check_bugs() to arch_cpu_finalize_init() which makes it
clear what this is about.
Move the invocation of arch_cpu_finalize_init() earlier in
start_kernel() as it has to be done before fork_init() which needs to
know the FPU register buffer size.
With those prerequisites the FPU initialization can be moved into
arch_cpu_finalize_init(), which removes it from the early and fragile
part of the x86 bringup.
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Merge tag 'x86-boot-2023-06-26' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 boot updates from Thomas Gleixner:
"Initialize FPU late.
Right now FPU is initialized very early during boot. There is no real
requirement to do so. The only requirement is to have it done before
alternatives are patched.
That's done in check_bugs() which does way more than what the function
name suggests.
So first rename check_bugs() to arch_cpu_finalize_init() which makes
it clear what this is about.
Move the invocation of arch_cpu_finalize_init() earlier in
start_kernel() as it has to be done before fork_init() which needs to
know the FPU register buffer size.
With those prerequisites the FPU initialization can be moved into
arch_cpu_finalize_init(), which removes it from the early and fragile
part of the x86 bringup"
* tag 'x86-boot-2023-06-26' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mem_encrypt: Unbreak the AMD_MEM_ENCRYPT=n build
x86/fpu: Move FPU initialization into arch_cpu_finalize_init()
x86/fpu: Mark init functions __init
x86/fpu: Remove cpuinfo argument from init functions
x86/init: Initialize signal frame size late
init, x86: Move mem_encrypt_init() into arch_cpu_finalize_init()
init: Invoke arch_cpu_finalize_init() earlier
init: Remove check_bugs() leftovers
um/cpu: Switch to arch_cpu_finalize_init()
sparc/cpu: Switch to arch_cpu_finalize_init()
sh/cpu: Switch to arch_cpu_finalize_init()
mips/cpu: Switch to arch_cpu_finalize_init()
m68k/cpu: Switch to arch_cpu_finalize_init()
loongarch/cpu: Switch to arch_cpu_finalize_init()
ia64/cpu: Switch to arch_cpu_finalize_init()
ARM: cpu: Switch to arch_cpu_finalize_init()
x86/cpu: Switch to arch_cpu_finalize_init()
init: Provide arch_cpu_finalize_init()
|
||
|
Thomas Gleixner
|
1703db2b90 |
x86/fpu: Mark init functions __init
No point in keeping them around. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230613224545.841685728@linutronix.de |
||
|
Thomas Gleixner
|
1f34bb2a24 |
x86/fpu: Remove cpuinfo argument from init functions
Nothing in the call chain requires it Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230613224545.783704297@linutronix.de |
||
|
Mike Christie
|
f9010dbdce |
fork, vhost: Use CLONE_THREAD to fix freezer/ps regression
When switching from kthreads to vhost_tasks two bugs were added:
1. The vhost worker tasks's now show up as processes so scripts doing
ps or ps a would not incorrectly detect the vhost task as another
process. 2. kthreads disabled freeze by setting PF_NOFREEZE, but
vhost tasks's didn't disable or add support for them.
To fix both bugs, this switches the vhost task to be thread in the
process that does the VHOST_SET_OWNER ioctl, and has vhost_worker call
get_signal to support SIGKILL/SIGSTOP and freeze signals. Note that
SIGKILL/STOP support is required because CLONE_THREAD requires
CLONE_SIGHAND which requires those 2 signals to be supported.
This is a modified version of the patch written by Mike Christie
<michael.christie@oracle.com> which was a modified version of patch
originally written by Linus.
Much of what depended upon PF_IO_WORKER now depends on PF_USER_WORKER.
Including ignoring signals, setting up the register state, and having
get_signal return instead of calling do_group_exit.
Tidied up the vhost_task abstraction so that the definition of
vhost_task only needs to be visible inside of vhost_task.c. Making
it easier to review the code and tell what needs to be done where.
As part of this the main loop has been moved from vhost_worker into
vhost_task_fn. vhost_worker now returns true if work was done.
The main loop has been updated to call get_signal which handles
SIGSTOP, freezing, and collects the message that tells the thread to
exit as part of process exit. This collection clears
__fatal_signal_pending. This collection is not guaranteed to
clear signal_pending() so clear that explicitly so the schedule()
sleeps.
For now the vhost thread continues to exist and run work until the
last file descriptor is closed and the release function is called as
part of freeing struct file. To avoid hangs in the coredump
rendezvous and when killing threads in a multi-threaded exec. The
coredump code and de_thread have been modified to ignore vhost threads.
Remvoing the special case for exec appears to require teaching
vhost_dev_flush how to directly complete transactions in case
the vhost thread is no longer running.
Removing the special case for coredump rendezvous requires either the
above fix needed for exec or moving the coredump rendezvous into
get_signal.
Fixes:
|
||
|
Chang S. Bae
|
b158888402 |
x86/fpu/xstate: Prevent false-positive warning in __copy_xstate_uabi_buf()
__copy_xstate_to_uabi_buf() copies either from the tasks XSAVE buffer
or from init_fpstate into the ptrace buffer. Dynamic features, like
XTILEDATA, have an all zeroes init state and are not saved in
init_fpstate, which means the corresponding bit is not set in the
xfeatures bitmap of the init_fpstate header.
But __copy_xstate_to_uabi_buf() retrieves addresses for both the tasks
xstate and init_fpstate unconditionally via __raw_xsave_addr().
So if the tasks XSAVE buffer has a dynamic feature set, then the
address retrieval for init_fpstate triggers the warning in
__raw_xsave_addr() which checks the feature bit in the init_fpstate
header.
Remove the address retrieval from init_fpstate for extended features.
They have an all zeroes init state so init_fpstate has zeros for them.
Then zeroing the user buffer for the init state is the same as copying
them from init_fpstate.
Fixes:
|
||
|
Linus Torvalds
|
2e0ddb34e5 |
Updates in this cycle:
- Replace zero-length array in struct xregs_state with flexible-array member,
to help the enabling of stricter compiler checks.
- Don't set TIF_NEED_FPU_LOAD for PF_IO_WORKER threads.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-fpu-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fpu updates from Ingo Molnar:
- Replace zero-length array in struct xregs_state with flexible-array
member, to help the enabling of stricter compiler checks.
- Don't set TIF_NEED_FPU_LOAD for PF_IO_WORKER threads.
* tag 'x86-fpu-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/fpu: Don't set TIF_NEED_FPU_LOAD for PF_IO_WORKER threads
x86/fpu: Replace zero-length array in struct xregs_state with flexible-array member
|
||
|
Jens Axboe
|
cb3ea4b767 |
x86/fpu: Don't set TIF_NEED_FPU_LOAD for PF_IO_WORKER threads
We don't set it on PF_KTHREAD threads as they never return to userspace, and PF_IO_WORKER threads are identical in that regard. As they keep running in the kernel until they die, skip setting the FPU flag on them. More of a cosmetic thing that was found while debugging and issue and pondering why the FPU flag is set on these threads. Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/560c844c-f128-555b-40c6-31baff27537f@kernel.dk |
||
|
Peter Zijlstra
|
821ad23d0e |
cpuidle, intel_idle: Fix CPUIDLE_FLAG_INIT_XSTATE
Fix instrumentation bugs objtool found: vmlinux.o: warning: objtool: intel_idle_s2idle+0xd5: call to fpu_idle_fpregs() leaves .noinstr.text section vmlinux.o: warning: objtool: intel_idle_xstate+0x11: call to fpu_idle_fpregs() leaves .noinstr.text section vmlinux.o: warning: objtool: fpu_idle_fpregs+0x9: call to xfeatures_in_use() leaves .noinstr.text section Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Tony Lindgren <tony@atomide.com> Tested-by: Ulf Hansson <ulf.hansson@linaro.org> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/20230112195540.494977795@infradead.org |
||
|
Linus Torvalds
|
40deb5e41a |
* Clarify XSAVE consistency warnings
* Fix up ptrace interface to protection keys register (PKRU) * Avoid undefined compiler behavior with TYPE_ALIGN -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEV76QKkVc4xCGURexaDWVMHDJkrAFAmOXYisACgkQaDWVMHDJ krAJkA//QRChRwyKi1syinXt2SGoSa3mTzP23SyV0TunOfKBiBUreFJ2mMFjsX0h V7SJcu82sCWLHAY6LZRdyiF8zK3Cfzpbgb1QfzBCefE/gU801FhCypqNbQO5Lpdr PEo+naaDOzwDWDt0A6OkAArgb0zfaOGL+OBhuwT7mcUtBz6gCakFqG2BMgOzqD1z SAp0RraoSsFnKFl5Gv44+gkThq8/8yL5tyrJtnGv1jAsbhw9zmloaOue6MNMPJhH 3sFQnML3qeNRozquWWeCPu/hxWuFDitPhwdmNRZrnQ3DyRdDhCZPOjv+tQmxI3EO 5c+UIkMIsRh2nZLwHcM+iO5cWE7lyiAWpgqqArB+r2CFXWK5q2lplhXngBodE9Kr ki/NZ6oEitT3+bLXhCwyc7WKxohl2IlmclJ4AD3Qrp4bzPhfsZebL6nNs/3bxWuF CxJWIKzjtIcgNSEJaDOzFA5CAImq74r/kCW4e11ZXwmOnx6PX1YG6p0C1yknrZYJ bvy8WxureO7OJEcVZfwxpXLYbb+7Q/k/l2DkUdVAvKSCB81uWR4JzEp4oooDxf2j 6x9qT5Mi95FhAHOCmlxwkQJTBCB36LkVF/3ESEOqJmun4F5ghPbMX2JzpBa6jPCS lzkBrzA8MAdmaLHhDO+nd5m8HVY3QBSXDVtRTycmuloeoSeyBno= =An0n -----END PGP SIGNATURE----- Merge tag 'x86_fpu_for_6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fpu updates from Dave Hansen: "There are two little fixes in here, one to give better XSAVE warnings and another to address some undefined behavior in offsetof(). There is also a collection of patches to fix some issues with ptrace and the protection keys register (PKRU). PKRU is a real oddity because it is exposed in the XSAVE-related ABIs, but it is generally managed without using XSAVE in the kernel. This fix thankfully came with a selftest to ward off future regressions. Summary: - Clarify XSAVE consistency warnings - Fix up ptrace interface to protection keys register (PKRU) - Avoid undefined compiler behavior with TYPE_ALIGN" * tag 'x86_fpu_for_6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fpu: Use _Alignof to avoid undefined behavior in TYPE_ALIGN selftests/vm/pkeys: Add a regression test for setting PKRU through ptrace x86/fpu: Emulate XRSTOR's behavior if the xfeatures PKRU bit is not set x86/fpu: Allow PKRU to be (once again) written by ptrace. x86/fpu: Add a pkru argument to copy_uabi_to_xstate() x86/fpu: Add a pkru argument to copy_uabi_from_kernel_to_xstate(). x86/fpu: Take task_struct* in copy_sigframe_from_user_to_xstate() x86/fpu/xstate: Fix XSTATE_WARN_ON() to emit relevant diagnostics |
||
|
YingChi Long
|
55228db269 |
x86/fpu: Use _Alignof to avoid undefined behavior in TYPE_ALIGN
WG14 N2350 specifies that it is an undefined behavior to have type definitions within offsetof", see https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm This specification is also part of C23. Therefore, replace the TYPE_ALIGN macro with the _Alignof builtin to avoid undefined behavior. (_Alignof itself is C11 and the kernel is built with -gnu11). ISO C11 _Alignof is subtly different from the GNU C extension __alignof__. Latter is the preferred alignment and _Alignof the minimal alignment. For long long on x86 these are 8 and 4 respectively. The macro TYPE_ALIGN's behavior matches _Alignof rather than __alignof__. [ bp: Massage commit message. ] Signed-off-by: YingChi Long <me@inclyc.cn> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://lore.kernel.org/r/20220925153151.2467884-1-me@inclyc.cn |
||
|
Kyle Huey
|
d7e5aceace |
x86/fpu: Emulate XRSTOR's behavior if the xfeatures PKRU bit is not set
The hardware XRSTOR instruction resets the PKRU register to its hardware
init value (namely 0) if the PKRU bit is not set in the xfeatures mask.
Emulating that here restores the pre-5.14 behavior for PTRACE_SET_REGSET
with NT_X86_XSTATE, and makes sigreturn (which still uses XRSTOR) and
ptrace behave identically. KVM has never used XRSTOR and never had this
behavior, so KVM opts-out of this emulation by passing a NULL pkru pointer
to copy_uabi_to_xstate().
Fixes:
|
||
|
Kyle Huey
|
4a804c4f83 |
x86/fpu: Allow PKRU to be (once again) written by ptrace.
Move KVM's PKRU handling code in fpu_copy_uabi_to_guest_fpstate() to
copy_uabi_to_xstate() so that it is shared with other APIs that write the
XSTATE such as PTRACE_SETREGSET with NT_X86_XSTATE.
This restores the pre-5.14 behavior of ptrace. The regression can be seen
by running gdb and executing `p $pkru`, `set $pkru = 42`, and `p $pkru`.
On affected kernels (5.14+) the write to the PKRU register (which gdb
performs through ptrace) is ignored.
[ dhansen: removed stable@ tag for now. The ABI was broken for long
enough that this is not urgent material. Let's let it stew
in tip for a few weeks before it's submitted to stable
because there are so many ABIs potentially affected. ]
Fixes:
|
||
|
Kyle Huey
|
2c87767c35 |
x86/fpu: Add a pkru argument to copy_uabi_to_xstate()
In preparation for moving PKRU handling code out of fpu_copy_uabi_to_guest_fpstate() and into copy_uabi_to_xstate(), add an argument that copy_uabi_from_kernel_to_xstate() can use to pass the canonical location of the PKRU value. For copy_sigframe_from_user_to_xstate() the kernel will actually restore the PKRU value from the fpstate, but pass in the thread_struct's pkru location anyways for consistency. Signed-off-by: Kyle Huey <me@kylehuey.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/all/20221115230932.7126-4-khuey%40kylehuey.com |
||
|
Kyle Huey
|
1c813ce030 |
x86/fpu: Add a pkru argument to copy_uabi_from_kernel_to_xstate().
Both KVM (through KVM_SET_XSTATE) and ptrace (through PTRACE_SETREGSET with NT_X86_XSTATE) ultimately call copy_uabi_from_kernel_to_xstate(), but the canonical locations for the current PKRU value for KVM guests and processes in a ptrace stop are different (in the kvm_vcpu_arch and the thread_state structs respectively). In preparation for eventually handling PKRU in copy_uabi_to_xstate, pass in a pointer to the PKRU location. Signed-off-by: Kyle Huey <me@kylehuey.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/all/20221115230932.7126-3-khuey%40kylehuey.com |
||
|
Kyle Huey
|
6a877d2450 |
x86/fpu: Take task_struct* in copy_sigframe_from_user_to_xstate()
This will allow copy_sigframe_from_user_to_xstate() to grab the address of thread_struct's pkru value in a later patch. Signed-off-by: Kyle Huey <me@kylehuey.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/all/20221115230932.7126-2-khuey%40kylehuey.com |
||
|
Mel Gorman
|
36b038791e |
x86/fpu: Drop fpregs lock before inheriting FPU permissions
Mike Galbraith reported the following against an old fork of preempt-rt
but the same issue also applies to the current preempt-rt tree.
BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: systemd
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
Preemption disabled at:
fpu_clone
CPU: 6 PID: 1 Comm: systemd Tainted: G E (unreleased)
Call Trace:
<TASK>
dump_stack_lvl
? fpu_clone
__might_resched
rt_spin_lock
fpu_clone
? copy_thread
? copy_process
? shmem_alloc_inode
? kmem_cache_alloc
? kernel_clone
? __do_sys_clone
? do_syscall_64
? __x64_sys_rt_sigprocmask
? syscall_exit_to_user_mode
? do_syscall_64
? syscall_exit_to_user_mode
? do_syscall_64
? syscall_exit_to_user_mode
? do_syscall_64
? exc_page_fault
? entry_SYSCALL_64_after_hwframe
</TASK>
Mike says:
The splat comes from fpu_inherit_perms() being called under fpregs_lock(),
and us reaching the spin_lock_irq() therein due to fpu_state_size_dynamic()
returning true despite static key __fpu_state_size_dynamic having never
been enabled.
Mike's assessment looks correct. fpregs_lock on a PREEMPT_RT kernel disables
preemption so calling spin_lock_irq() in fpu_inherit_perms() is unsafe. This
problem exists since commit
|
||
|
Andrew Cooper
|
48280042f2 |
x86/fpu/xstate: Fix XSTATE_WARN_ON() to emit relevant diagnostics
"XSAVE consistency problem" has been reported under Xen, but that's the extent of my divination skills. Modify XSTATE_WARN_ON() to force the caller to provide relevant diagnostic information, and modify each caller suitably. For check_xstate_against_struct(), this removes a double WARN() where one will do perfectly fine. CC stable as this has been wonky debugging for 7 years and it is good to have there too. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20220810221909.12768-1-andrew.cooper3@citrix.com |
||
|
Chang S. Bae
|
471f0aa7fa |
x86/fpu: Fix copy_xstate_to_uabi() to copy init states correctly
When an extended state component is not present in fpstate, but in init
state, the function copies from init_fpstate via copy_feature().
But, dynamic states are not present in init_fpstate because of all-zeros
init states. Then retrieving them from init_fpstate will explode like this:
BUG: kernel NULL pointer dereference, address: 0000000000000000
...
RIP: 0010:memcpy_erms+0x6/0x10
? __copy_xstate_to_uabi_buf+0x381/0x870
fpu_copy_guest_fpstate_to_uabi+0x28/0x80
kvm_arch_vcpu_ioctl+0x14c/0x1460 [kvm]
? __this_cpu_preempt_check+0x13/0x20
? vmx_vcpu_put+0x2e/0x260 [kvm_intel]
kvm_vcpu_ioctl+0xea/0x6b0 [kvm]
? kvm_vcpu_ioctl+0xea/0x6b0 [kvm]
? __fget_light+0xd4/0x130
__x64_sys_ioctl+0xe3/0x910
? debug_smp_processor_id+0x17/0x20
? fpregs_assert_state_consistent+0x27/0x50
do_syscall_64+0x3f/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Adjust the 'mask' to zero out the userspace buffer for the features that
are not available both from fpstate and from init_fpstate.
The dynamic features depend on the compacted XSAVE format. Ensure it is
enabled before reading XCOMP_BV in init_fpstate.
Fixes:
|
||
|
Chang S. Bae
|
a401f45e38 |
x86/fpu: Exclude dynamic states from init_fpstate
== Background ==
The XSTATE init code initializes all enabled and supported components.
Then, the init states are saved in the init_fpstate buffer that is
statically allocated in about one page.
The AMX TILE_DATA state is large (8KB) but its init state is zero. And the
feature comes only with the compacted format with these established
dependencies: AMX->XFD->XSAVES. So this state is excludable from
init_fpstate.
== Problem ==
But the buffer is formatted to include that large state. Then, this can be
the cause of a noisy splat like the below.
This came from XRSTORS for the task with init_fpstate in its XSAVE buffer.
It is reproducible on AMX systems when the running kernel is built with
CONFIG_DEBUG_PAGEALLOC=y and CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT=y:
Bad FPU state detected at restore_fpregs_from_fpstate+0x57/0xd0, reinitializing FPU registers.
...
RIP: 0010:restore_fpregs_from_fpstate+0x57/0xd0
? restore_fpregs_from_fpstate+0x45/0xd0
switch_fpu_return+0x4e/0xe0
exit_to_user_mode_prepare+0x17b/0x1b0
syscall_exit_to_user_mode+0x29/0x40
do_syscall_64+0x67/0x80
? do_syscall_64+0x67/0x80
? exc_page_fault+0x86/0x180
entry_SYSCALL_64_after_hwframe+0x63/0xcd
== Solution ==
Adjust init_fpstate to exclude dynamic states. XRSTORS from init_fpstate
still initializes those states when their bits are set in the
requested-feature bitmap.
Fixes:
|
||
|
Chang S. Bae
|
d3e021adac |
x86/fpu: Fix the init_fpstate size check with the actual size
The init_fpstate buffer is statically allocated. Thus, the sanity test was
established to check whether the pre-allocated buffer is enough for the
calculated size or not.
The currently measured size is not strictly relevant. Fix to validate the
calculated init_fpstate size with the pre-allocated area.
Also, replace the sanity check function with open code for clarity. The
abstraction itself and the function naming do not tend to represent simply
what it does.
Fixes:
|
||
|
Chang S. Bae
|
c32d7cab57 |
x86/fpu: Configure init_fpstate attributes orderly
The init_fpstate setup code is spread out and out of order. The init image is recorded before its scoped features and the buffer size are determined. Determine the scope of init_fpstate components and its size before recording the init state. Also move the relevant code together. Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: neelnatu@google.com Link: https://lore.kernel.org/r/20220824191223.1248-2-chang.seok.bae@intel.com |
||
|
Chang S. Bae
|
f17b168734 |
x86/fpu: Add a helper to prepare AMX state for low-power CPU idle
When a CPU enters an idle state, a non-initialized AMX register state may be the cause of preventing a deeper low-power state. Other extended register states whether initialized or not do not impact the CPU idle state. The new helper can ensure the AMX state is initialized before the CPU is idle, and it will be used by the intel idle driver. Check the AMX_TILE feature bit before using XGETBV1 as a chain of dependencies was established via cpuid_deps[]: AMX->XFD->XGETBV1. Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20220608164748.11864-2-chang.seok.bae@intel.com |
||
|
Linus Torvalds
|
1ec6574a3c |
This set of changes updates init and user mode helper tasks to be
ordinary user mode tasks. In commit |
||
|
Linus Torvalds
|
bf9095424d |
S390:
* ultravisor communication device driver
* fix TEID on terminating storage key ops
RISC-V:
* Added Sv57x4 support for G-stage page table
* Added range based local HFENCE functions
* Added remote HFENCE functions based on VCPU requests
* Added ISA extension registers in ONE_REG interface
* Updated KVM RISC-V maintainers entry to cover selftests support
ARM:
* Add support for the ARMv8.6 WFxT extension
* Guard pages for the EL2 stacks
* Trap and emulate AArch32 ID registers to hide unsupported features
* Ability to select and save/restore the set of hypercalls exposed
to the guest
* Support for PSCI-initiated suspend in collaboration with userspace
* GICv3 register-based LPI invalidation support
* Move host PMU event merging into the vcpu data structure
* GICv3 ITS save/restore fixes
* The usual set of small-scale cleanups and fixes
x86:
* New ioctls to get/set TSC frequency for a whole VM
* Allow userspace to opt out of hypercall patching
* Only do MSR filtering for MSRs accessed by rdmsr/wrmsr
AMD SEV improvements:
* Add KVM_EXIT_SHUTDOWN metadata for SEV-ES
* V_TSC_AUX support
Nested virtualization improvements for AMD:
* Support for "nested nested" optimizations (nested vVMLOAD/VMSAVE,
nested vGIF)
* Allow AVIC to co-exist with a nested guest running
* Fixes for LBR virtualizations when a nested guest is running,
and nested LBR virtualization support
* PAUSE filtering for nested hypervisors
Guest support:
* Decoupling of vcpu_is_preempted from PV spinlocks
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Paolo Bonzini:
"S390:
- ultravisor communication device driver
- fix TEID on terminating storage key ops
RISC-V:
- Added Sv57x4 support for G-stage page table
- Added range based local HFENCE functions
- Added remote HFENCE functions based on VCPU requests
- Added ISA extension registers in ONE_REG interface
- Updated KVM RISC-V maintainers entry to cover selftests support
ARM:
- Add support for the ARMv8.6 WFxT extension
- Guard pages for the EL2 stacks
- Trap and emulate AArch32 ID registers to hide unsupported features
- Ability to select and save/restore the set of hypercalls exposed to
the guest
- Support for PSCI-initiated suspend in collaboration with userspace
- GICv3 register-based LPI invalidation support
- Move host PMU event merging into the vcpu data structure
- GICv3 ITS save/restore fixes
- The usual set of small-scale cleanups and fixes
x86:
- New ioctls to get/set TSC frequency for a whole VM
- Allow userspace to opt out of hypercall patching
- Only do MSR filtering for MSRs accessed by rdmsr/wrmsr
AMD SEV improvements:
- Add KVM_EXIT_SHUTDOWN metadata for SEV-ES
- V_TSC_AUX support
Nested virtualization improvements for AMD:
- Support for "nested nested" optimizations (nested vVMLOAD/VMSAVE,
nested vGIF)
- Allow AVIC to co-exist with a nested guest running
- Fixes for LBR virtualizations when a nested guest is running, and
nested LBR virtualization support
- PAUSE filtering for nested hypervisors
Guest support:
- Decoupling of vcpu_is_preempted from PV spinlocks"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (199 commits)
KVM: x86: Fix the intel_pt PMI handling wrongly considered from guest
KVM: selftests: x86: Sync the new name of the test case to .gitignore
Documentation: kvm: reorder ARM-specific section about KVM_SYSTEM_EVENT_SUSPEND
x86, kvm: use correct GFP flags for preemption disabled
KVM: LAPIC: Drop pending LAPIC timer injection when canceling the timer
x86/kvm: Alloc dummy async #PF token outside of raw spinlock
KVM: x86: avoid calling x86 emulator without a decoded instruction
KVM: SVM: Use kzalloc for sev ioctl interfaces to prevent kernel data leak
x86/fpu: KVM: Set the base guest FPU uABI size to sizeof(struct kvm_xsave)
s390/uv_uapi: depend on CONFIG_S390
KVM: selftests: x86: Fix test failure on arch lbr capable platforms
KVM: LAPIC: Trace LAPIC timer expiration on every vmentry
KVM: s390: selftest: Test suppression indication on key prot exception
KVM: s390: Don't indicate suppression on dirtying, failing memop
selftests: drivers/s390x: Add uvdevice tests
drivers/s390/char: Add Ultravisor io device
MAINTAINERS: Update KVM RISC-V entry to cover selftests support
RISC-V: KVM: Introduce ISA extension register
RISC-V: KVM: Cleanup stale TLB entries when host CPU changes
RISC-V: KVM: Add remote HFENCE functions based on VCPU requests
...
|
||
|
Sean Christopherson
|
d187ba5312 |
x86/fpu: KVM: Set the base guest FPU uABI size to sizeof(struct kvm_xsave)
Set the starting uABI size of KVM's guest FPU to 'struct kvm_xsave', i.e. to KVM's historical uABI size. When saving FPU state for usersapce, KVM (well, now the FPU) sets the FP+SSE bits in the XSAVE header even if the host doesn't support XSAVE. Setting the XSAVE header allows the VM to be migrated to a host that does support XSAVE without the new host having to handle FPU state that may or may not be compatible with XSAVE. Setting the uABI size to the host's default size results in out-of-bounds writes (setting the FP+SSE bits) and data corruption (that is thankfully caught by KASAN) when running on hosts without XSAVE, e.g. on Core2 CPUs. WARN if the default size is larger than KVM's historical uABI size; all features that can push the FPU size beyond the historical size must be opt-in. ================================================================== BUG: KASAN: slab-out-of-bounds in fpu_copy_uabi_to_guest_fpstate+0x86/0x130 Read of size 8 at addr ffff888011e33a00 by task qemu-build/681 CPU: 1 PID: 681 Comm: qemu-build Not tainted 5.18.0-rc5-KASAN-amd64 #1 Hardware name: /DG35EC, BIOS ECG3510M.86A.0118.2010.0113.1426 01/13/2010 Call Trace: <TASK> dump_stack_lvl+0x34/0x45 print_report.cold+0x45/0x575 kasan_report+0x9b/0xd0 fpu_copy_uabi_to_guest_fpstate+0x86/0x130 kvm_arch_vcpu_ioctl+0x72a/0x1c50 [kvm] kvm_vcpu_ioctl+0x47f/0x7b0 [kvm] __x64_sys_ioctl+0x5de/0xc90 do_syscall_64+0x31/0x50 entry_SYSCALL_64_after_hwframe+0x44/0xae </TASK> Allocated by task 0: (stack is not available) The buggy address belongs to the object at ffff888011e33800 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes to the right of 512-byte region [ffff888011e33800, ffff888011e33a00) The buggy address belongs to the physical page: page:0000000089cd4adb refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11e30 head:0000000089cd4adb order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 dead000000000100 dead000000000122 ffff888001041c80 raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888011e33900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888011e33980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888011e33a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff888011e33a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888011e33b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== Disabling lock debugging due to kernel taint Fixes: |
||
|
Linus Torvalds
|
e36ae2290f |
- Add support for XSAVEC - the Compacted XSTATE saving variant - and
thus allow for guests to use this compacted XSTATE variant when the hypervisor exports that support - A variable shadowing cleanup -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmKLsPQACgkQEsHwGGHe VUoA7hAAoAP6qWntADHcDcA8QMjX9fvOi3uFjiJyGeiYCRH2rmwAAg8Y0DdI/1UE Wq+7tzTPdyDPulqaEe9PV7f3HRY72cGA/2jdkMxkGG5mGZfVganb0OWgFXecdo6r CIWf9vMOPwULIT4XvcnaWF6fv+1ZbFZOks9NpxZQZTYA3WQhozgfQOWlkoFFSdC/ pIwWFCUOv/pBPWVSeizE/Y6Yfuaix3KiElwk9NMDTPCRhyBd6VmpkpcBer+n3JUA HoppbGLYonZEw1PkMmTlQJuFHKJzqwThGGoVY3FDtlAMD4+vmGt1vXNbLlfvtqup zYHAIG/hqql7Ai9bgXSC2ccYG9v1op+gIFzKTBhI7FkVwEc6R6JtV7uGF7GAr6SL KPnweo9GCoRmnc6Ju0+IuT0JIMXjO3iQIC0J3uLX8gCbsXVM29qdqhkYcLC75vOc sXjAUrdolkDIRXzwkJURTxWT/yeKaN9n8r1s7BCmZ7Pg6zZS3/K1nHQkFTWCjSfA oEy7GmEeI2uFgQX9qpF7NRlNj+D3AxV6W5IURCTI7GsP32e20jhOdU4AyrqsTy2N 8PgUVP9baioUpjY6BKsMc3JiR0ihb0OM3wX9fThu8lu5uHE9Oar+S4OOlFtxPXth kG7pIS0MqB4N6aKWDFxvLvlUVgAxSqSmnWL4rQSP+Ralu9CY4k0= =eDaz -----END PGP SIGNATURE----- Merge tag 'x86_fpu_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fpu updates from Borislav Petkov: - Add support for XSAVEC - the Compacted XSTATE saving variant - and thus allow for guests to use this compacted XSTATE variant when the hypervisor exports that support - A variable shadowing cleanup * tag 'x86_fpu_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fpu: Cleanup variable shadowing x86/fpu/xsave: Support XSAVEC in the kernel |
||
|
Linus Torvalds
|
a13dc4d409 |
- Serious sanitization and cleanup of the whole APERF/MPERF and
frequency invariance code along with removing the need for unnecessary IPIs - Finally remove a.out support - The usual trivial cleanups and fixes all over x86 -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmKLn48ACgkQEsHwGGHe VUpbkg/+PELrc0y/qxLM/+dyftKYY16Rhk6ZVAXfwqlh5ldyVQcLMUgKwDqYyTn2 XmgdI3cTcFlH2K7j6ANWLu0I9NPaviimUcEdMVcXt7aY5mGWk/q4hIyCYM8d41sV qKx4OjNSdyoofG6MtwFLJDuoeVg99Bqgvm4nP9BuxL0dZJ2hfcUZ7MTxYCx9ZYjK /3trx0NV287Yg/wm91EU0nLQzy9xbGS7WCmMnse6uxiUdm2vXbBt8oNFF4f747Dj 0cArfNrMgYq4Cv5bgt/Ki0NU/n4EOGDpJUSyQwlnjDKeN81ESPy7IWtTQ6cE/rJK BZeUIPiGiYHwtqXv0UTAPGLG8cAqKeab8u0xAOyrFVDkTc0+WlPJRsUAOmRRGIGE M8ZjoxrLeuFgxw6vKpVjaA+mDRj3qEpSH+IrTcekS98PN7gmVzvq03GobgGbT7YB xmtbThJa+514FfUVckkyC0+A56BknUIgVxwFPqrthE2atzYTbH67hW4U0yVWXXr7 2VI7ttozBrYVgHCWhD9eoT0uhyD74Vl6pqHnqzY9ShIfKVUGvMgKHHg04nLLtF7W hm87xV3Q5UEmXhTmDzT1rUZ99mBUxGbWxk227I9raMugIh7pp9wIr57+7O0LRYfX TdnE2+tL8RMi7+XzRH5iLhnwkrvahBESeHSQ7GVI1Y2zMmmFN+0= =Dks/ -----END PGP SIGNATURE----- Merge tag 'x86_cleanups_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cleanups from Borislav Petkov: - Serious sanitization and cleanup of the whole APERF/MPERF and frequency invariance code along with removing the need for unnecessary IPIs - Finally remove a.out support - The usual trivial cleanups and fixes all over x86 * tag 'x86_cleanups_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits) x86: Remove empty files x86/speculation: Add missing srbds=off to the mitigations= help text x86/prctl: Remove pointless task argument x86/aperfperf: Make it correct on 32bit and UP kernels x86/aperfmperf: Integrate the fallback code from show_cpuinfo() x86/aperfmperf: Replace arch_freq_get_on_cpu() x86/aperfmperf: Replace aperfmperf_get_khz() x86/aperfmperf: Store aperf/mperf data for cpu frequency reads x86/aperfmperf: Make parts of the frequency invariance code unconditional x86/aperfmperf: Restructure arch_scale_freq_tick() x86/aperfmperf: Put frequency invariance aperf/mperf data into a struct x86/aperfmperf: Untangle Intel and AMD frequency invariance init x86/aperfmperf: Separate AP/BP frequency invariance init x86/smp: Move APERF/MPERF code where it belongs x86/aperfmperf: Dont wake idle CPUs in arch_freq_get_on_cpu() x86/process: Fix kernel-doc warning due to a changed function name x86: Remove a.out support x86/mm: Replace nodes_weight() with nodes_empty() where appropriate x86: Replace cpumask_weight() with cpumask_empty() where appropriate x86/pkeys: Remove __arch_set_user_pkey_access() declaration ... |
||
|
Thomas Gleixner
|
f5c0b4f304 |
x86/prctl: Remove pointless task argument
The functions invoked via do_arch_prctl_common() can only operate on the current task and none of these function uses the task argument. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/87lev7vtxj.ffs@tglx |
||
|
Eric W. Biederman
|
5bd2e97c86 |
fork: Generalize PF_IO_WORKER handling
Add fn and fn_arg members into struct kernel_clone_args and test for them in copy_thread (instead of testing for PF_KTHREAD | PF_IO_WORKER). This allows any task that wants to be a user space task that only runs in kernel mode to use this functionality. The code on x86 is an exception and still retains a PF_KTHREAD test because x86 unlikely everything else handles kthreads slightly differently than user space tasks that start with a function. The functions that created tasks that start with a function have been updated to set ".fn" and ".fn_arg" instead of ".stack" and ".stack_size". These functions are fork_idle(), create_io_thread(), kernel_thread(), and user_mode_thread(). Link: https://lkml.kernel.org/r/20220506141512.516114-4-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> |
||
|
Thomas Gleixner
|
59f5ede3bc |
x86/fpu: Prevent FPU state corruption
The FPU usage related to task FPU management is either protected by
disabling interrupts (switch_to, return to user) or via fpregs_lock() which
is a wrapper around local_bh_disable(). When kernel code wants to use the
FPU then it has to check whether it is possible by calling irq_fpu_usable().
But the condition in irq_fpu_usable() is wrong. It allows FPU to be used
when:
!in_interrupt() || interrupted_user_mode() || interrupted_kernel_fpu_idle()
The latter is checking whether some other context already uses FPU in the
kernel, but if that's not the case then it allows FPU to be used
unconditionally even if the calling context interrupted a fpregs_lock()
critical region. If that happens then the FPU state of the interrupted
context becomes corrupted.
Allow in kernel FPU usage only when no other context has in kernel FPU
usage and either the calling context is not hard interrupt context or the
hard interrupt did not interrupt a local bottomhalf disabled region.
It's hard to find a proper Fixes tag as the condition was broken in one way
or the other for a very long time and the eager/lazy FPU changes caused a
lot of churn. Picked something remotely connected from the history.
This survived undetected for quite some time as FPU usage in interrupt
context is rare, but the recent changes to the random code unearthed it at
least on a kernel which had FPU debugging enabled. There is probably a
higher rate of silent corruption as not all issues can be detected by the
FPU debugging code. This will be addressed in a subsequent change.
Fixes:
|
||
|
Thomas Gleixner
|
b91c0922bf |
x86/fpu: Cleanup variable shadowing
Addresses: warning: Local variable 'mask' shadows outer variable
Remove extra variable declaration and switch the bit mask assignment to use
BIT_ULL() while at it.
Fixes:
|
||
|
Thomas Gleixner
|
8ad7e8f696 |
x86/fpu/xsave: Support XSAVEC in the kernel
XSAVEC is the user space counterpart of XSAVES which cannot save supervisor state. In virtualization scenarios the hypervisor does not expose XSAVES but XSAVEC to the guest, though the kernel does not make use of it. That's unfortunate because XSAVEC uses the compacted format of saving the XSTATE. This is more efficient in terms of storage space vs. XSAVE[OPT] as it does not create holes for XSTATE components which are not supported or enabled by the kernel but are available in hardware. There is room for further optimizations when XSAVEC/S and XGETBV1 are supported. In order to support XSAVEC: - Define the XSAVEC ASM macro as it's not yet supported by the required minimal toolchain. - Create a software defined X86_FEATURE_XCOMPACTED to select the compacted XSTATE buffer format for both XSAVEC and XSAVES. - Make XSAVEC an option in the 'XSAVE' ASM alternatives Requested-by: Andrew Cooper <Andrew.Cooper3@citrix.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20220404104820.598704095@linutronix.de |
||
|
Thomas Gleixner
|
d6d6d50f1e |
x86/fpu/xstate: Consolidate size calculations
Use the offset calculation to do the size calculation which avoids yet
another series of CPUID instructions for each invocation.
[ Fix the FP/SSE only case which missed to take the xstate
header into account, as
Reported-by: kernel test robot <oliver.sang@intel.com> ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/87o81pgbp2.ffs@tglx
|
||
|
Thomas Gleixner
|
781c64bfcb |
x86/fpu/xstate: Handle supervisor states in XSTATE permissions
The size calculation in __xstate_request_perm() fails to take supervisor
states into account because the permission bitmap is only relevant for user
states.
Up to 5.17 this does not matter because there are no supervisor states
supported, but the (re-)enabling of ENQCMD makes them available.
Fixes:
|
||
|
Thomas Gleixner
|
7aa5128b5f |
x86/fpu/xsave: Handle compacted offsets correctly with supervisor states
So far the cached fixed compacted offsets worked, but with (re-)enabling
of ENQCMD this does no longer work with KVM fpstate.
KVM does not have supervisor features enabled for the guest FPU, which
means that KVM has then a different XSAVE area layout than the host FPU
state. This in turn breaks the copy from/to UABI functions when invoked for
a guest state.
Remove the pre-calculated compacted offsets and calculate the offset
of each component at runtime based on the XCOMP_BV field in the XSAVE
header.
The runtime overhead is not interesting because these copy from/to UABI
functions are not used in critical fast paths. KVM uses them to save and
restore FPU state during migration. The host uses them for ptrace and for
the slow path of 32bit signal handling.
Fixes:
|
||
|
Thomas Gleixner
|
6afbb58cc2 |
x86/fpu: Cache xfeature flags from CPUID
In preparation for runtime calculation of XSAVE offsets cache the feature
flags for each XSTATE component during feature enumeration via CPUID(0xD).
EDX has two relevant bits:
0 Supervisor component
1 Feature storage must be 64 byte aligned
These bits are currently only evaluated during init, but the alignment bit
must be cached to make runtime calculation of XSAVE offsets efficient.
Cache the full EDX content and use it for the existing alignment and
supervisor checks.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220324134623.573656209@linutronix.de
|
||
|
Thomas Gleixner
|
35a77d4503 |
x86/fpu/xsave: Initialize offset/size cache early
Reading XSTATE feature information from CPUID over and over does not make sense. The information has to be cached anyway, so it can be done early. Prepare for runtime calculation of XSTATE offsets and allow consolidation of the size calculation functions in a later step. Rename the function while at it as it does not setup any features. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220324134623.519411939@linutronix.de |
||
|
Thomas Gleixner
|
d47f71f6de |
x86/fpu: Remove unused supervisor only offsets
No users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220324134623.465066249@linutronix.de |
||
|
Thomas Gleixner
|
a9f84fb715 |
x86/fpu: Remove redundant XCOMP_BV initialization
fpu_copy_uabi_to_guest_fpstate() initializes the XCOMP_BV field in the
XSAVE header. That's a leftover from the old KVM FPU buffer handling code.
Since
|
||
|
Yang Zhong
|
063452fd94 |
x86/fpu/xstate: Fix the ARCH_REQ_XCOMP_PERM implementation
ARCH_REQ_XCOMP_PERM is supposed to add the requested feature to the
permission bitmap of thread_group_leader()->fpu. But the code overwrites
the bitmap with the requested feature bit only rather than adding it.
Fix the code to add the requested feature bit to the master bitmask.
Fixes:
|
||
|
Linus Torvalds
|
3fd33273a4 |
Reenable ENQCMD/PASID support:
- Simplify the PASID handling to allocate the PASID once, associate it to
the mm of a process and free it on mm_exit(). The previous attempt of
refcounted PASIDs and dynamic alloc()/free() turned out to be error
prone and too complex. The PASID space is 20bits, so the case of
resource exhaustion is a pure academic concern.
- Populate the PASID MSR on demand via #GP to avoid racy updates via IPIs.
- Reenable ENQCMD and let objtool check for the forbidden usage of ENQCMD
in the kernel.
- Update the documentation for Shared Virtual Addressing accordingly.
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Merge tag 'x86-pasid-2022-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 PASID support from Thomas Gleixner:
"Reenable ENQCMD/PASID support:
- Simplify the PASID handling to allocate the PASID once, associate
it to the mm of a process and free it on mm_exit().
The previous attempt of refcounted PASIDs and dynamic
alloc()/free() turned out to be error prone and too complex. The
PASID space is 20bits, so the case of resource exhaustion is a pure
academic concern.
- Populate the PASID MSR on demand via #GP to avoid racy updates via
IPIs.
- Reenable ENQCMD and let objtool check for the forbidden usage of
ENQCMD in the kernel.
- Update the documentation for Shared Virtual Addressing accordingly"
* tag 'x86-pasid-2022-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Documentation/x86: Update documentation for SVA (Shared Virtual Addressing)
tools/objtool: Check for use of the ENQCMD instruction in the kernel
x86/cpufeatures: Re-enable ENQCMD
x86/traps: Demand-populate PASID MSR via #GP
sched: Define and initialize a flag to identify valid PASID in the task
x86/fpu: Clear PASID when copying fpstate
iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit
kernel/fork: Initialize mm's PASID
iommu/ioasid: Introduce a helper to check for valid PASIDs
mm: Change CONFIG option for mm->pasid field
iommu/sva: Rename CONFIG_IOMMU_SVA_LIB to CONFIG_IOMMU_SVA
|
||
|
Linus Torvalds
|
1f840c0ef4 |
x86 host:
* Expose KVM_CAP_ENABLE_CAP since it is supported * Disable KVM_HC_CLOCK_PAIRING in TSC catchup mode * Ensure async page fault token is nonzero * Fix lockdep false negative * Fix FPU migration regression from the AMX changes x86 guest: * Don't use PV TLB/IPI/yield on uniprocessor guests PPC: * reserve capability id (topic branch for ppc/kvm) -----BEGIN PGP SIGNATURE----- iQFIBAABCAAyFiEE8TM4V0tmI4mGbHaCv/vSX3jHroMFAmIXyQAUHHBib256aW5p QHJlZGhhdC5jb20ACgkQv/vSX3jHroPKJQf/T9NeXOFIPIIlH4ZKM7155qlwX8dx NR2YV+RNYd27MDkaEm9w4ucXacGpPuBPPx9v7UiLlAqAN+NP7nF3rQKC0SpQMC6H EKFtm+8al8EzyDYP36fqnwDne/xWHlOeGXRRJMKPGhXBSoXoY5cK35IXmNZjfteQ hK7siBs2saJ2VFqMCbJ9Pqdu1NDO6OEt8HWz2Dnx6EUd90O0pHWZy5JvWOYfyLjL Y2pP0dZQxuB/PmqkpVj2gV9jK2Zhj33eerzDV4tVXPV7le8fgGeTaJ8ft+SUIizS YCcPR89+u5c9yzlwY2i7mvloayKnuqkECiGtRG6VHNlrPZTPijems8tH1w== =lWjy -----END PGP SIGNATURE----- Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm Pull kvm fixes from Paolo Bonzini: "x86 host: - Expose KVM_CAP_ENABLE_CAP since it is supported - Disable KVM_HC_CLOCK_PAIRING in TSC catchup mode - Ensure async page fault token is nonzero - Fix lockdep false negative - Fix FPU migration regression from the AMX changes x86 guest: - Don't use PV TLB/IPI/yield on uniprocessor guests PPC: - reserve capability id (topic branch for ppc/kvm)" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: KVM: x86: nSVM: disallow userspace setting of MSR_AMD64_TSC_RATIO to non default value when tsc scaling disabled KVM: x86/mmu: make apf token non-zero to fix bug KVM: PPC: reserve capability 210 for KVM_CAP_PPC_AIL_MODE_3 x86/kvm: Don't use pv tlb/ipi/sched_yield if on 1 vCPU x86/kvm: Fix compilation warning in non-x86_64 builds x86/kvm/fpu: Remove kvm_vcpu_arch.guest_supported_xcr0 x86/kvm/fpu: Limit guest user_xfeatures to supported bits of XCR0 kvm: x86: Disable KVM_HC_CLOCK_PAIRING if tsc is in always catchup mode KVM: Fix lockdep false negative during host resume KVM: x86: Add KVM_CAP_ENABLE_CAP to x86 |
||
|
Andy Lutomirski
|
44cad52cc1 |
x86/ptrace: Fix xfpregs_set()'s incorrect xmm clearing
xfpregs_set() handles 32-bit REGSET_XFP and 64-bit REGSET_FP. The actual
code treats these regsets as modern FX state (i.e. the beginning part of
XSTATE). The declarations of the regsets thought they were the legacy
i387 format. The code thought they were the 32-bit (no xmm8..15) variant
of XSTATE and, for good measure, made the high bits disappear by zeroing
the wrong part of the buffer. The latter broke ptrace, and everything
else confused anyone trying to understand the code. In particular, the
nonsense definitions of the regsets confused me when I wrote this code.
Clean this all up. Change the declarations to match reality (which
shouldn't change the generated code, let alone the ABI) and fix
xfpregs_set() to clear the correct bits and to only do so for 32-bit
callers.
Fixes:
|
||
|
Leonardo Bras
|
ad856280dd |
x86/kvm/fpu: Limit guest user_xfeatures to supported bits of XCR0
During host/guest switch (like in kvm_arch_vcpu_ioctl_run()), the kernel
swaps the fpu between host/guest contexts, by using fpu_swap_kvm_fpstate().
When xsave feature is available, the fpu swap is done by:
- xsave(s) instruction, with guest's fpstate->xfeatures as mask, is used
to store the current state of the fpu registers to a buffer.
- xrstor(s) instruction, with (fpu_kernel_cfg.max_features &
XFEATURE_MASK_FPSTATE) as mask, is used to put the buffer into fpu regs.
For xsave(s) the mask is used to limit what parts of the fpu regs will
be copied to the buffer. Likewise on xrstor(s), the mask is used to
limit what parts of the fpu regs will be changed.
The mask for xsave(s), the guest's fpstate->xfeatures, is defined on
kvm_arch_vcpu_create(), which (in summary) sets it to all features
supported by the cpu which are enabled on kernel config.
This means that xsave(s) will save to guest buffer all the fpu regs
contents the cpu has enabled when the guest is paused, even if they
are not used.
This would not be an issue, if xrstor(s) would also do that.
xrstor(s)'s mask for host/guest swap is basically every valid feature
contained in kernel config, except XFEATURE_MASK_PKRU.
Accordingto kernel src, it is instead switched in switch_to() and
flush_thread().
Then, the following happens with a host supporting PKRU starts a
guest that does not support it:
1 - Host has XFEATURE_MASK_PKRU set. 1st switch to guest,
2 - xsave(s) fpu regs to host fpustate (buffer has XFEATURE_MASK_PKRU)
3 - xrstor(s) guest fpustate to fpu regs (fpu regs have XFEATURE_MASK_PKRU)
4 - guest runs, then switch back to host,
5 - xsave(s) fpu regs to guest fpstate (buffer now have XFEATURE_MASK_PKRU)
6 - xrstor(s) host fpstate to fpu regs.
7 - kvm_vcpu_ioctl_x86_get_xsave() copy guest fpstate to userspace (with
XFEATURE_MASK_PKRU, which should not be supported by guest vcpu)
On 5, even though the guest does not support PKRU, it does have the flag
set on guest fpstate, which is transferred to userspace via vcpu ioctl
KVM_GET_XSAVE.
This becomes a problem when the user decides on migrating the above guest
to another machine that does not support PKRU: the new host restores
guest's fpu regs to as they were before (xrstor(s)), but since the new
host don't support PKRU, a general-protection exception ocurs in xrstor(s)
and that crashes the guest.
This can be solved by making the guest's fpstate->user_xfeatures hold
a copy of guest_supported_xcr0. This way, on 7 the only flags copied to
userspace will be the ones compatible to guest requirements, and thus
there will be no issue during migration.
As a bonus, it will also fail if userspace tries to set fpu features
(with the KVM_SET_XSAVE ioctl) that are not compatible to the guest
configuration. Such features will never be returned by KVM_GET_XSAVE
or KVM_GET_XSAVE2.
Also, since kvm_vcpu_after_set_cpuid() now sets fpstate->user_xfeatures,
there is not need to set it in kvm_check_cpuid(). So, change
fpstate_realloc() so it does not touch fpstate->user_xfeatures if a
non-NULL guest_fpu is passed, which is the case when kvm_check_cpuid()
calls it.
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Message-Id: <20220217053028.96432-2-leobras@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
|
||
|
Fenghua Yu
|
dc7507ddce |
x86/fpu: Clear PASID when copying fpstate
The kernel must allocate a Process Address Space ID (PASID) on behalf of each process which will use ENQCMD and program it into the new MSR to communicate the process identity to platform hardware. ENQCMD uses the PASID stored in this MSR to tag requests from this process. The PASID state must be cleared on fork() since fork creates a new address space. For clone(), it would be functionally OK to copy the PASID. However, clearing it is _also_ functionally OK since any PASID use will trigger the #GP handler to populate the MSR. Copying the PASID state has two main downsides: * It requires differentiating fork() and clone() in the code, both in the FPU code and keeping tsk->pasid_activated consistent. * It guarantees that the PASID is out of its init state, which incurs small but non-zero cost on every XSAVE/XRSTOR. The main downside of clearing the PASID at fpstate copy is the future, one-time #GP for the thread. Use the simplest approach: clear the PASID state both on clone() and fork(). Rely on the #GP handler for MSR population in children. Also, just clear the PASID bit from xfeatures if XSAVE is supported. This will have no effect on systems that do not have PASID support. It is virtually zero overhead because 'dst_fpu' was just written and the whole thing is cache hot. Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20220207230254.3342514-7-fenghua.yu@intel.com |
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Linus Torvalds
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79e06c4c49 |
RISCV:
- Use common KVM implementation of MMU memory caches
- SBI v0.2 support for Guest
- Initial KVM selftests support
- Fix to avoid spurious virtual interrupts after clearing hideleg CSR
- Update email address for Anup and Atish
ARM:
- Simplification of the 'vcpu first run' by integrating it into
KVM's 'pid change' flow
- Refactoring of the FP and SVE state tracking, also leading to
a simpler state and less shared data between EL1 and EL2 in
the nVHE case
- Tidy up the header file usage for the nvhe hyp object
- New HYP unsharing mechanism, finally allowing pages to be
unmapped from the Stage-1 EL2 page-tables
- Various pKVM cleanups around refcounting and sharing
- A couple of vgic fixes for bugs that would trigger once
the vcpu xarray rework is merged, but not sooner
- Add minimal support for ARMv8.7's PMU extension
- Rework kvm_pgtable initialisation ahead of the NV work
- New selftest for IRQ injection
- Teach selftests about the lack of default IPA space and
page sizes
- Expand sysreg selftest to deal with Pointer Authentication
- The usual bunch of cleanups and doc update
s390:
- fix sigp sense/start/stop/inconsistency
- cleanups
x86:
- Clean up some function prototypes more
- improved gfn_to_pfn_cache with proper invalidation, used by Xen emulation
- add KVM_IRQ_ROUTING_XEN_EVTCHN and event channel delivery
- completely remove potential TOC/TOU races in nested SVM consistency checks
- update some PMCs on emulated instructions
- Intel AMX support (joint work between Thomas and Intel)
- large MMU cleanups
- module parameter to disable PMU virtualization
- cleanup register cache
- first part of halt handling cleanups
- Hyper-V enlightened MSR bitmap support for nested hypervisors
Generic:
- clean up Makefiles
- introduce CONFIG_HAVE_KVM_DIRTY_RING
- optimize memslot lookup using a tree
- optimize vCPU array usage by converting to xarray
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Paolo Bonzini:
"RISCV:
- Use common KVM implementation of MMU memory caches
- SBI v0.2 support for Guest
- Initial KVM selftests support
- Fix to avoid spurious virtual interrupts after clearing hideleg CSR
- Update email address for Anup and Atish
ARM:
- Simplification of the 'vcpu first run' by integrating it into KVM's
'pid change' flow
- Refactoring of the FP and SVE state tracking, also leading to a
simpler state and less shared data between EL1 and EL2 in the nVHE
case
- Tidy up the header file usage for the nvhe hyp object
- New HYP unsharing mechanism, finally allowing pages to be unmapped
from the Stage-1 EL2 page-tables
- Various pKVM cleanups around refcounting and sharing
- A couple of vgic fixes for bugs that would trigger once the vcpu
xarray rework is merged, but not sooner
- Add minimal support for ARMv8.7's PMU extension
- Rework kvm_pgtable initialisation ahead of the NV work
- New selftest for IRQ injection
- Teach selftests about the lack of default IPA space and page sizes
- Expand sysreg selftest to deal with Pointer Authentication
- The usual bunch of cleanups and doc update
s390:
- fix sigp sense/start/stop/inconsistency
- cleanups
x86:
- Clean up some function prototypes more
- improved gfn_to_pfn_cache with proper invalidation, used by Xen
emulation
- add KVM_IRQ_ROUTING_XEN_EVTCHN and event channel delivery
- completely remove potential TOC/TOU races in nested SVM consistency
checks
- update some PMCs on emulated instructions
- Intel AMX support (joint work between Thomas and Intel)
- large MMU cleanups
- module parameter to disable PMU virtualization
- cleanup register cache
- first part of halt handling cleanups
- Hyper-V enlightened MSR bitmap support for nested hypervisors
Generic:
- clean up Makefiles
- introduce CONFIG_HAVE_KVM_DIRTY_RING
- optimize memslot lookup using a tree
- optimize vCPU array usage by converting to xarray"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (268 commits)
x86/fpu: Fix inline prefix warnings
selftest: kvm: Add amx selftest
selftest: kvm: Move struct kvm_x86_state to header
selftest: kvm: Reorder vcpu_load_state steps for AMX
kvm: x86: Disable interception for IA32_XFD on demand
x86/fpu: Provide fpu_sync_guest_vmexit_xfd_state()
kvm: selftests: Add support for KVM_CAP_XSAVE2
kvm: x86: Add support for getting/setting expanded xstate buffer
x86/fpu: Add uabi_size to guest_fpu
kvm: x86: Add CPUID support for Intel AMX
kvm: x86: Add XCR0 support for Intel AMX
kvm: x86: Disable RDMSR interception of IA32_XFD_ERR
kvm: x86: Emulate IA32_XFD_ERR for guest
kvm: x86: Intercept #NM for saving IA32_XFD_ERR
x86/fpu: Prepare xfd_err in struct fpu_guest
kvm: x86: Add emulation for IA32_XFD
x86/fpu: Provide fpu_update_guest_xfd() for IA32_XFD emulation
kvm: x86: Enable dynamic xfeatures at KVM_SET_CPUID2
x86/fpu: Provide fpu_enable_guest_xfd_features() for KVM
x86/fpu: Add guest support to xfd_enable_feature()
...
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Yang Zhong
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c862dcd199 |
x86/fpu: Fix inline prefix warnings
Fix sparse warnings in xstate and remove inline prefix.
Fixes:
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Thomas Gleixner
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5429cead01 |
x86/fpu: Provide fpu_sync_guest_vmexit_xfd_state()
KVM can disable the write emulation for the XFD MSR when the vCPU's fpstate is already correctly sized to reduce the overhead. When write emulation is disabled the XFD MSR state after a VMEXIT is unknown and therefore not in sync with the software states in fpstate and the per CPU XFD cache. Provide fpu_sync_guest_vmexit_xfd_state() which has to be invoked after a VMEXIT before enabling interrupts when write emulation is disabled for the XFD MSR. It could be invoked unconditionally even when write emulation is enabled for the price of a pointless MSR read. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Jing Liu <jing2.liu@intel.com> Signed-off-by: Yang Zhong <yang.zhong@intel.com> Message-Id: <20220105123532.12586-21-yang.zhong@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |