Commit Graph

1427348 Commits

Author SHA1 Message Date
Sean Christopherson
25a642b6ab KVM: selftests: Remove duplicate LAUNCH_UPDATE_VMSA call in SEV-ES migrate test
Drop the explicit KVM_SEV_LAUNCH_UPDATE_VMSA call when creating an SEV-ES
VM in the SEV migration test, as sev_vm_create() automatically updates the
VMSA pages for SEV-ES guests.  The only reason the duplicate call doesn't
cause visible problems is because the test doesn't actually try to run the
vCPUs.  That will change when KVM adds a check to prevent userspace from
re-launching a VMSA (which corrupts the VMSA page due to KVM writing
encrypted private memory).

Fixes: 69f8e15ab6 ("KVM: selftests: Use the SEV library APIs in the intra-host migration test")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260310234829.2608037-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-04-03 09:37:35 -07:00
Sean Christopherson
a7f53694d5 KVM: SEV: Use kvzalloc_objs() when pinning userpages
Use kvzalloc_objs() instead of sev_pin_memory()'s open coded (rough)
equivalent to harden the code and

Note!  This sanity check in __kvmalloc_node_noprof()

  /* Don't even allow crazy sizes */
  if (unlikely(size > INT_MAX)) {
          WARN_ON_ONCE(!(flags & __GFP_NOWARN));
          return NULL;
  }

will artificially limit the maximum size of any single pinned region to
just under 1TiB.  While there do appear to be providers that support SEV
VMs with more than 1TiB of _total_ memory, it's unlikely any KVM-based
providers pin 1TiB in a single request.

Allocate with NOWARN so that fuzzers can't trip the WARN_ON_ONCE() when
they inevitably run on systems with copious amounts of RAM, i.e. when they
can get by KVM's "total_npages > totalram_pages()" restriction.

Note #2, KVM's usage of vmalloc()+kmalloc() instead of kvmalloc() predates
commit 7661809d49 ("mm: don't allow oversized kvmalloc() calls") by 4+
years (see commit 89c5058090 ("KVM: SVM: Add support for
KVM_SEV_LAUNCH_UPDATE_DATA command").  I.e. the open coded behavior wasn't
intended to avoid the aforementioned sanity check.  The implementation
appears to be pure oversight at the time the code was written, as it showed
up in v3[1] of the early RFCs, whereas as v2[2] simply used kmalloc().

Cc: Liam Merwick <liam.merwick@oracle.com>
Link: https://lore.kernel.org/all/20170724200303.12197-17-brijesh.singh@amd.com [1]
Link: https://lore.kernel.org/all/148846786714.2349.17724971671841396908.stgit__25299.4950431914$1488470940$gmane$org@brijesh-build-machine [2]
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Tested-by: Liam Merwick <liam.merwick@oracle.com>
Link: https://patch.msgid.link/20260313003302.3136111-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-04-03 09:37:25 -07:00
Sean Christopherson
7ad02ff1e4 KVM: SEV: Use PFN_DOWN() to simplify "number of pages" math when pinning memory
Use PFN_DOWN() instead of open coded equivalents in sev_pin_memory() to
simplify the code and make it easier to read.

No functional change intended (verified before and after versions of the
generated code are identical).

Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Tested-by: Liam Merwick <liam.merwick@oracle.com>
Link: https://patch.msgid.link/20260313003302.3136111-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-04-03 09:37:25 -07:00
Sean Christopherson
6d71f9349d KVM: SEV: Disallow pinning more pages than exist in the system
Explicitly disallow pinning more pages for an SEV VM than exist in the
system to defend against absurd userspace requests without relying on
somewhat arbitrary kernel functionality to prevent truly stupid KVM
behavior.  E.g. even with the INT_MAX check, userspace can request that
KVM pin nearly 8TiB of memory, regardless of how much RAM exists in the
system.

Opportunistically rename "locked" to a more descriptive "total_npages".

Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Tested-by: Liam Merwick <liam.merwick@oracle.com>
Link: https://patch.msgid.link/20260313003302.3136111-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-04-03 09:37:25 -07:00
Sean Christopherson
12a8ff869d KVM: SEV: Drop useless sanity checks in sev_mem_enc_register_region()
Drop sev_mem_enc_register_region()'s sanity checks on the incoming address
and size, as SEV is 64-bit only, making ULONG_MAX a 64-bit, all-ones value,
and thus making it impossible for kvm_enc_region.{addr,size} to be greater
than ULONG_MAX.

Note, sev_pin_memory() verifies the incoming address is non-NULL (which
isn't strictly required, but whatever), and that addr+size don't wrap to
zero (which _is_ needed and what really needs to be guarded against).

Note #2, pin_user_pages_fast() guards against the end address walking into
kernel address space, so lack of an access_ok() check is also safe (maybe
not ideal, but safe).

No functional change intended (the generated code is literally the same,
i.e. the compiler was smart enough to know the checks were useless).

Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Tested-by: Liam Merwick <liam.merwick@oracle.com>
Link: https://patch.msgid.link/20260313003302.3136111-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-04-03 09:37:25 -07:00
Sean Christopherson
8acffeef5e KVM: SEV: Drop WARN on large size for KVM_MEMORY_ENCRYPT_REG_REGION
Drop the WARN in sev_pin_memory() on npages overflowing an int, as the
WARN is comically trivially to trigger from userspace, e.g. by doing:

  struct kvm_enc_region range = {
          .addr = 0,
          .size = -1ul,
  };

  __vm_ioctl(vm, KVM_MEMORY_ENCRYPT_REG_REGION, &range);

Note, the checks in sev_mem_enc_register_region() that presumably exist to
verify the incoming address+size are completely worthless, as both "addr"
and "size" are u64s and SEV is 64-bit only, i.e. they _can't_ be greater
than ULONG_MAX.  That wart will be cleaned up in the near future.

	if (range->addr > ULONG_MAX || range->size > ULONG_MAX)
		return -EINVAL;

Opportunistically add a comment to explain why the code calculates the
number of pages the "hard" way, e.g. instead of just shifting @ulen.

Fixes: 78824fabc7 ("KVM: SVM: fix svn_pin_memory()'s use of get_user_pages_fast()")
Cc: stable@vger.kernel.org
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Tested-by: Liam Merwick <liam.merwick@oracle.com>
Link: https://patch.msgid.link/20260313003302.3136111-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-04-03 09:37:25 -07:00
Sean Christopherson
a56444d5e7 KVM: SVM: Skip OSVW MSR reads if current CPU doesn't support the feature
Skip the OSVW RDMSRs if the current CPU doesn't enumerate support for the
MSRs.  In practice, checking only the boot CPU's capabilities is
sufficient, as the RDMSRs should fault when unsupported, but there's no
downside to being more precise, and checking only the boot CPU _looks_
wrong given the rather odd semantics of the MSRs.  E.g. if a CPU doesn't
support OVSW, then KVM must assume all errata are present.

Link: https://patch.msgid.link/20251113231420.1695919-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-03 12:23:26 -08:00
Sean Christopherson
3b7a320e49 KVM: SVM: Skip OSVW variable updates if current CPU's errata are a subset
Elide the OSVW variable updates if the current CPU's set of errata are a
subset of the errata tracked in the global values, i.e. if no update is
needed.  There's no danger of under-reporting errata due to bailing early
as KVM is purely reducing the set of "known fixed" errata.  I.e. a racing
update on a different CPU with _more_ errata doesn't change anything if
the current CPU has the same or fewer errata relative to the status quo.

If another CPU is writing osvw_len, then "len" is guaranteed to be larger
than the new osvw_len and so the osvw_len update would be skipped anyways.

If another CPU is setting new bits in osvw_status, then "status" is
guaranteed to be a subset of the new osvw_status and the bitwise-OR would
be an effective nop anyways.

Link: https://patch.msgid.link/20251113231420.1695919-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-03 12:23:26 -08:00
Sean Christopherson
c65106af83 KVM: SVM: Extract OS-visible workarounds setup to helper function
Move the initialization of the global OSVW variables to a helper function
so that svm_enable_virtualization_cpu() isn't polluted with a pile of what
is effectively legacy code.

No functional change intended.

Link: https://patch.msgid.link/20251113231420.1695919-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-03 12:23:26 -08:00
Sean Christopherson
089af84641 KVM: SVM: Skip OSVW MSR reads if KVM is treating all errata as present
Don't bother reading the OSVW MSRs if osvw_len is already zero, i.e. if
KVM is already treating all errata as present, in which case the positive
path of the if-statement is one giant nop.

Opportunistically update the comment to more thoroughly explain how the
MSRs work and why the code does what it does.

Link: https://patch.msgid.link/20251113231420.1695919-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-03 12:23:26 -08:00
Sean Christopherson
f35043d0f9 KVM: SVM: Serialize updates to global OS-Visible Workarounds variables
Guard writes to the global osvw_status and osvw_len variables with a
spinlock to ensure enabling virtualization on multiple CPUs in parallel
doesn't effectively drop any writes due to writing back stale data.  Don't
bother taking the lock when the boot CPU doesn't support the feature, as
that check is constant for all CPUs, i.e. racing writes will always write
the same value (zero).

Note, the bug was inadvertently "fixed" by commit 9a798b1337 ("KVM:
Register cpuhp and syscore callbacks when enabling hardware"), which
effectively serialized calls to enable virtualization due to how the cpuhp
framework "brings up" CPU.  But KVM shouldn't rely on the mechanics of
cphup to provide serialization.

Link: https://patch.msgid.link/20251113231420.1695919-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-03 12:23:26 -08:00
Gal Pressman
2b1a59f7ef KVM: SVM: Fix UBSAN warning when reading avic parameter
The avic parameter is stored as an int to support the special value -1
(AVIC_AUTO_MODE), but the cited commit changed it from bool to int while
keeping param_get_bool() as the getter function.
This causes UBSAN to report "load of value 255 is not a valid value for
type '_Bool'" when the parameter is read via sysfs.

The issue happens in two scenarios:

1. During module load: There's a time window between when module
   parameters are registered, and when avic_hardware_setup() runs to
   resolve the value, where the value is -1.

2. On non-AMD systems: On non-AMD hardware, the kvm_is_svm_supported()
   check returns early. The avic_hardware_setup() function never runs,
   so avic remains -1.

Fix that by implementing a getter function that properly reads and
converts the -1 value into a string.

Triggered by sos report:
  UBSAN: invalid-load in kernel/params.c:323:33
  load of value 255 is not a valid value for type '_Bool'
  CPU: 0 UID: 0 PID: 4667 Comm: sos Not tainted 6.19.0-rc5net_mlx5_1e86836 #1 NONE
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
  Call Trace:
   <TASK>
   dump_stack_lvl+0x69/0xa0
   ubsan_epilogue+0x5/0x2b
   __ubsan_handle_load_invalid_value.cold+0x47/0x4c
   ? lock_acquire+0x219/0x2c0
   param_get_bool.cold+0xf/0x14
   param_attr_show+0x51/0x80
   module_attr_show+0x19/0x30
   sysfs_kf_seq_show+0xac/0xf0
   seq_read_iter+0x100/0x410
   copy_splice_read+0x1b4/0x360
   splice_direct_to_actor+0xbd/0x270
   ? wait_for_space+0xb0/0xb0
   do_splice_direct+0x72/0xb0
   ? propagate_umount+0x870/0x870
   do_sendfile+0x3a3/0x470
   __x64_sys_sendfile64+0x5e/0xe0
   do_syscall_64+0x70/0x8c0
   entry_SYSCALL_64_after_hwframe+0x4b/0x53

Fixes: ca2967de5a ("KVM: SVM: Enable AVIC by default for Zen4+ if x2AVIC is support")
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Naveen N Rao (AMD) <naveen@kernel.org>
Link: https://patch.msgid.link/20260225145050.2350278-2-gal@nvidia.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-02 16:11:18 -08:00
Sean Christopherson
fa78a514d6 KVM: Isolate apicv_update_lock and apicv_nr_irq_window_req in a cacheline
Force apicv_update_lock and apicv_nr_irq_window_req to reside in their own
cacheline to avoid generating significant contention due to false sharing
when KVM is contantly creating IRQ windows.  E.g. apicv_inhibit_reasons is
read on every VM-Enter; disabled_exits is read on page faults, on PAUSE
exits, if a vCPU is scheduled out, etc.; kvmclock_offset is read every time
a vCPU needs to refresh kvmclock, and so on and so forth.

Isolating the write-mostly fields from all other (read-mostly) fields
improves performance by 7-8% when running netperf TCP_RR between two guests
on the same physical host when using an in-kernel PIT in re-inject mode.

Reported-by: Naveen N Rao (AMD) <naveen@kernel.org>
Closes: https://lore.kernel.org/all/yrxhngndj37edud6tj5y3vunaf7nirwor4n63yf4275wdocnd3@c77ujgialc6r
Tested-by: Naveen N Rao (AMD) <naveen@kernel.org>
Link: https://patch.msgid.link/20260123224514.2509129-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-02 14:51:36 -08:00
Sean Christopherson
5617dddcfa KVM: SVM: Optimize IRQ window inhibit handling
IRQ windows represent times during which an IRQ can be injected into a
vCPU, and thus represent times when a vCPU is running with RFLAGS.IF=1
and GIF enabled (TPR/PPR don't matter since KVM controls interrupt
injection and it only injects one interrupt at a time). On SVM, when
emulating the local APIC (i.e., AVIC disabled), KVM detects IRQ windows
by injecting a dummy virtual interrupt through VMCB.V_IRQ and
intercepting virtual interrupts (INTERCEPT_VINTR). This intercept
triggers as soon as the guest enables interrupts and is about to take
the dummy interrupt, at which point the actual interrupt can be injected
through VMCB.EVENTINJ.

When AVIC is enabled, VMCB.V_IRQ is ignored by the hardware and so
detecting IRQ windows requires AVIC to be inhibited. However, this is
only necessary for ExtINTs since all other interrupts can be injected
either by directly setting IRR in the APIC backing page and letting the
AVIC hardware inject the interrupt into the guest, or via VMCB.V_NMI for
NMIs.

If AVIC is enabled but inhibited for some other reason, KVM has to
request for IRQ window inhibits every time it has to inject an interrupt
into the guest. This is because APICv inhibits are dynamic in nature, so
KVM has to be sure that AVIC is inhibited for purposes of discovering an
IRQ window even if the other inhibit is cleared in the meantime.

This is particularly problematic with APICV_INHIBIT_REASON_PIT_REINJ
which stays set throughout the life of the guest and results in KVM
rapidly toggling IRQ window inhibit resulting in contention on
apicv_update_lock.

Address this by setting and clearing APICV_INHIBIT_REASON_PIT_REINJ
lazily: if some other inhibit reason is already set, just increment the
IRQ window request count and do not update apicv_inhibit_reasons
immediately. If any other inhibit reason is set/cleared in the meantime,
re-evaluate APICV_INHIBIT_REASON_PIT_REINJ by checking the IRQ window
request count and update apicv_inhibit_reasons appropriately. Otherwise,
just the IRQ window request count is incremented/decremented each time
an IRQ window is requested. This reduces much of the contention on the
apicv_update_lock semaphore and does away with much of the performance
degradation.

Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Co-developed-by: Naveen N Rao (AMD) <naveen@kernel.org>
Signed-off-by: Naveen N Rao (AMD) <naveen@kernel.org>
Tested-by: Naveen N Rao (AMD) <naveen@kernel.org>
Link: https://patch.msgid.link/20260123224514.2509129-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-02 14:51:36 -08:00
Sean Christopherson
6563ddadd1 KVM: SVM: Fix IRQ window inhibit handling across multiple vCPUs
IRQ window inhibits can be requested by multiple vCPUs at the same time
for injecting interrupts meant for different vCPUs. However, AVIC
inhibition is VM-wide and hence it is possible for the inhibition to be
cleared prematurely by the first vCPU that obtains the IRQ window even
though a second vCPU is still waiting for its IRQ window. This is likely
not a functional issue since the other vCPU will again see that
interrupts are pending to be injected (due to KVM_REQ_EVENT), and will
again request for an IRQ window inhibition. However, this can result in
AVIC being rapidly toggled resulting in high contention on
apicv_update_lock and degrading performance of the guest.

Address this by maintaining a VM-wide count of the number of vCPUs that
have requested for an IRQ window. Set/clear the inhibit reason when the
count transitions between 0 and 1. This ensures that the inhibit reason
is not cleared as long as there are some vCPUs still waiting for an IRQ
window.

Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Co-developed-by: Naveen N Rao (AMD) <naveen@kernel.org>
Signed-off-by: Naveen N Rao (AMD) <naveen@kernel.org>
Tested-by: Naveen N Rao (AMD) <naveen@kernel.org>
Link: https://patch.msgid.link/20260123224514.2509129-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-02 14:51:36 -08:00
Sean Christopherson
7b402ec851 KVM: SVM: Fix clearing IRQ window inhibit with nested guests
Clearing IRQ window inhibit today relies on interrupt window
interception, but that is not always reachable when nested guests are
involved.

If L1 is intercepting IRQs, then interrupt_window_interception() will
never be reached while L2 is active, because the only reason KVM
would set the V_IRQ intercept in vmcb02 would be on behalf of L1, i.e.
because of vmcb12.  svm_clear_vintr() always operates on (at least)
vmcb01, and VMRUN unconditionally sets GIF=1, which means that
enter_svm_guest_mode() will always do svm_clear_vintr() via
svm_set_gif(svm, true). I.e. KVM will keep the VM-wide inhibit set until
control transfers back to L1 *and* an interrupt window is triggered.

If L1 is not intercepting IRQs, KVM may immediately inject L1's ExtINT
into L2 if IRQs are enabled in L2 without taking an interrupt window
interception.

Address this by clearing the IRQ window inhibit when KVM actually
injects an interrupt and there are no further injectable interrupts.
That way, if L1 isn't intercepting IRQs, KVM will drop the inhibit as
soon as an interrupt is injected into L2. And if L1 is intercepting
IRQs, KVM will keep the inhibit until the IRQ is injected into L2. So,
AVIC won't be left inhibited.

Note, somewhat blindly invoking kvm_clear_apicv_inhibit() is both wrong
and suboptimal.  If the IRQWIN inhibit isn't set, then the vCPU will
unnecessarily take apicv_update_lock for write.  And if a _different_ vCPU
has an injectable IRQ, clearing IRQWIN may block that vCPU's ability to
inject its IRQ.  Defer fixing both issues to a future commit, as fixing
one problem without also fixing the other would also leave KVM in a
temporarily bad state, as would fixing both issues without fixing _this_
bug.  I.e. it's not feasible to fix each bug independently without there
being some remaining flaw in KVM.

Co-developed-by: Naveen N Rao (AMD) <naveen@kernel.org>
Signed-off-by: Naveen N Rao (AMD) <naveen@kernel.org>
Tested-by: Naveen N Rao (AMD) <naveen@kernel.org>
Link: https://patch.msgid.link/20260123224514.2509129-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-02 14:51:36 -08:00
Li RongQing
52de184bad KVM: SVM: Mark module parameters as __ro_after_init for security and performance
SVM module parameters such as avic, sev_enabled, npt_enabled, and
pause_filter_thresh are configured exclusively during initialization
(via kernel command line) and remain constant throughout runtime.
Additionally, sev_supported_vmsa_features and svm_gp_erratum_intercept,
while not exposed as module parameters, share the same initialization
pattern and runtime constancy.

Mark these variables with '__ro_after_init' to:
- Harden against accidental or malicious runtime modification
- Enable compiler and CPU optimizations (improved caching, branch prediction)
- Align with kernel security best practices for init-only configuration

The exception is 'iopm_base', which retains '__read_mostly' as it requires
updates during module unloading.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Link: https://patch.msgid.link/20260202095004.1765-1-lirongqing@baidu.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2026-03-02 14:50:39 -08:00
Linus Torvalds
11439c4635 Linux 7.0-rc2 2026-03-01 15:39:31 -08:00
Linus Torvalds
949d0a46ad Arm:
* Make sure we don't leak any S1POE state from guest to guest when
   the feature is supported on the HW, but not enabled on the host
 
 * Propagate the ID registers from the host into non-protected VMs
   managed by pKVM, ensuring that the guest sees the intended feature set
 
 * Drop double kern_hyp_va() from unpin_host_sve_state(), which could
   bite us if we were to change kern_hyp_va() to not being idempotent
 
 * Don't leak stage-2 mappings in protected mode
 
 * Correctly align the faulting address when dealing with single page
   stage-2 mappings for PAGE_SIZE > 4kB
 
 * Fix detection of virtualisation-capable GICv5 IRS, due to the
   maintainer being obviously fat fingered... [his words, not mine]
 
 * Remove duplication of code retrieving the ASID for the purpose of
   S1 PT handling
 
 * Fix slightly abusive const-ification in vgic_set_kvm_info()
 
 Generic:
 
 * Remove internal Kconfigs that are now set on all architectures.
 
 * Remove per-architecture code to enable KVM_CAP_SYNC_MMU, all
   architectures finally enable it in Linux 7.0.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "Arm:

   - Make sure we don't leak any S1POE state from guest to guest when
     the feature is supported on the HW, but not enabled on the host

   - Propagate the ID registers from the host into non-protected VMs
     managed by pKVM, ensuring that the guest sees the intended feature
     set

   - Drop double kern_hyp_va() from unpin_host_sve_state(), which could
     bite us if we were to change kern_hyp_va() to not being idempotent

   - Don't leak stage-2 mappings in protected mode

   - Correctly align the faulting address when dealing with single page
     stage-2 mappings for PAGE_SIZE > 4kB

   - Fix detection of virtualisation-capable GICv5 IRS, due to the
     maintainer being obviously fat fingered... [his words, not mine]

   - Remove duplication of code retrieving the ASID for the purpose of
     S1 PT handling

   - Fix slightly abusive const-ification in vgic_set_kvm_info()

  Generic:

   - Remove internal Kconfigs that are now set on all architectures

   - Remove per-architecture code to enable KVM_CAP_SYNC_MMU, all
     architectures finally enable it in Linux 7.0"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: always define KVM_CAP_SYNC_MMU
  KVM: remove CONFIG_KVM_GENERIC_MMU_NOTIFIER
  KVM: arm64: Deduplicate ASID retrieval code
  irqchip/gic-v5: Fix inversion of IRS_IDR0.virt flag
  KVM: arm64: Revert accidental drop of kvm_uninit_stage2_mmu() for non-NV VMs
  KVM: arm64: Fix protected mode handling of pages larger than 4kB
  KVM: arm64: vgic: Handle const qualifier from gic_kvm_info allocation type
  KVM: arm64: Remove redundant kern_hyp_va() in unpin_host_sve_state()
  KVM: arm64: Fix ID register initialization for non-protected pKVM guests
  KVM: arm64: Optimise away S1POE handling when not supported by host
  KVM: arm64: Hide S1POE from guests when not supported by the host
2026-03-01 15:34:47 -08:00
Linus Torvalds
e2bd1b1369 A single fix for debugobjects.
The deferred page initialization prevents debug objects from allocating
 slab pages until the initialization is complete. That causes depletion of
 the pool and disabling of debugobjects.
 
 The reason is that debugobjects uses __GFP_HIGH for allocations as it might
 be invoked from arbitrary contexts. When PREEMPT_COUNT is disabled there is
 no way to know whether the context is safe to set __GFP_KSWAPD_RECLAIM.
 
 This worked until v6.18. Since then allocations w/o a reclaim flag cause
 new_slab() to end up in alloc_frozen_pages_nolock_noprof(), which returns
 early when deferred page initialization has not yet completed.
 
 Work around that when PREEMPT_COUNT is enabled as the preempt counter
 allows debugobjects to add __GFP_KSWAPD_RECLAIM to the GFP flags when the
 context is preemtible. When PREEMPT_COUNT is disabled the context is
 unknown and the reclaim bit can't be set because the caller might hold
 locks which might deadlock in the allocator.
 
 That makes debugobjects depend on PREEMPT_COUNT || !DEFERRED_STRUCT_PAGE_INIT,
 which limits the coverage slightly, but keeps it functional for most cases.
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Merge tag 'core-debugobjects-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull debugobjects fix from Thomas Gleixner:
 "A single fix for debugobjects.

  The deferred page initialization prevents debug objects from
  allocating slab pages until the initialization is complete. That
  causes depletion of the pool and disabling of debugobjects.

  The reason is that debugobjects uses __GFP_HIGH for allocations as it
  might be invoked from arbitrary contexts. When PREEMPT_COUNT is
  disabled there is no way to know whether the context is safe to set
  __GFP_KSWAPD_RECLAIM.

  This worked until v6.18. Since then allocations w/o a reclaim flag
  cause new_slab() to end up in alloc_frozen_pages_nolock_noprof(),
  which returns early when deferred page initialization has not yet
  completed.

  Work around that when PREEMPT_COUNT is enabled as the preempt counter
  allows debugobjects to add __GFP_KSWAPD_RECLAIM to the GFP flags when
  the context is preemtible. When PREEMPT_COUNT is disabled the context
  is unknown and the reclaim bit can't be set because the caller might
  hold locks which might deadlock in the allocator.

  That makes debugobjects depend on PREEMPT_COUNT ||
  !DEFERRED_STRUCT_PAGE_INIT, which limits the coverage slightly, but
  keeps it functional for most cases"

* tag 'core-debugobjects-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  debugobject: Make it work with deferred page initialization - again
2026-03-01 13:32:32 -08:00
Linus Torvalds
5920da4455 Miscellaneous x86 fixes:
- Fix speculative safety in fred_extint()
 
  - Fix __WARN_printf() trap in early_fixup_exception()
 
  - Fix clang-build boot bug for unusual alignments,
    triggered by CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_64B=y
 
  - Replace the final few __ASSEMBLY__ stragglers that snuck
    in lately into non-UAPI x86 headers and use __ASSEMBLER__
    consistently (again).
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:

 - Fix speculative safety in fred_extint()

 - Fix __WARN_printf() trap in early_fixup_exception()

 - Fix clang-build boot bug for unusual alignments, triggered by
   CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_64B=y

 - Replace the final few __ASSEMBLY__ stragglers that snuck in lately
   into non-UAPI x86 headers and use __ASSEMBLER__ consistently (again)

* tag 'x86-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/headers: Replace __ASSEMBLY__ stragglers with __ASSEMBLER__
  x86/cfi: Fix CFI rewrite for odd alignments
  x86/bug: Handle __WARN_printf() trap in early_fixup_exception()
  x86/fred: Correct speculative safety in fred_extint()
2026-03-01 13:16:35 -08:00
Linus Torvalds
f6542af922 Improve the inlining of jiffies_to_msecs() and jiffies_to_usecs(),
for the common HZ=100, 250 or 1000 cases, only inlining them
 for odd HZ values like HZ=300.
 
 The inlining overhead showed up in performance tests of the TCP code.
 
 (Marked as an RFC pull request, as it's not a regression.)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'timers-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer fix from Ingo Molnar:
 "Improve the inlining of jiffies_to_msecs() and jiffies_to_usecs(), for
  the common HZ=100, 250 or 1000 cases. Only use a function call for odd
  HZ values like HZ=300 that generate more code.

  The function call overhead showed up in performance tests of the TCP
  code"

* tag 'timers-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  time/jiffies: Inline jiffies_to_msecs() and jiffies_to_usecs()
2026-03-01 12:15:58 -08:00
Linus Torvalds
6170625149 Miscellaneous fixes:
- Fix zero_vruntime tracking when there's a single task running
 
  - Fix slice protection logic
 
  - Fix the ->vprot logic for reniced tasks
 
  - Fix lag clamping in mixed slice workloads
 
  - Fix objtool uaccess warning (and bug) in the
    !CONFIG_RSEQ_SLICE_EXTENSION case caused by unexpected
    un-inlining, which triggers with older compilers
 
  - Fix a comment in the rseq registration rseq_size bound check code
 
  - Fix a legacy RSEQ ABI quirk that handled 32-byte area sizes
    differently, which special size we now reached naturally and
    want to avoid. The visible ugliness of the new reserved field
    will be avoided the next time the RSEQ area is extended.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Ingo Molnar:

 - Fix zero_vruntime tracking when there's a single task running

 - Fix slice protection logic

 - Fix the ->vprot logic for reniced tasks

 - Fix lag clamping in mixed slice workloads

 - Fix objtool uaccess warning (and bug) in the
   !CONFIG_RSEQ_SLICE_EXTENSION case caused by unexpected un-inlining,
   which triggers with older compilers

 - Fix a comment in the rseq registration rseq_size bound check code

 - Fix a legacy RSEQ ABI quirk that handled 32-byte area sizes
   differently, which special size we now reached naturally and want to
   avoid. The visible ugliness of the new reserved field will be avoided
   the next time the RSEQ area is extended.

* tag 'sched-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rseq: slice ext: Ensure rseq feature size differs from original rseq size
  rseq: Clarify rseq registration rseq_size bound check comment
  sched/core: Fix wakeup_preempt's next_class tracking
  rseq: Mark rseq_arm_slice_extension_timer() __always_inline
  sched/fair: Fix lag clamp
  sched/eevdf: Update se->vprot in reweight_entity()
  sched/fair: Only set slice protection at pick time
  sched/fair: Fix zero_vruntime tracking
2026-03-01 11:09:24 -08:00
Linus Torvalds
cb36eabcaf Miscellaneous fixes:
- Fix lock ordering bug found by lockdep in perf_event_wakeup()
  - Fix uncore counter enumeration on Granite Rapids and Sierra Forest
  - Fix perf_mmap() refcount bug found by Syzkaller
  - Fix __perf_event_overflow() vs. perf_remove_from_context() race
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf events fixes from Ingo Molnar:

 - Fix lock ordering bug found by lockdep in perf_event_wakeup()

 - Fix uncore counter enumeration on Granite Rapids and Sierra Forest

 - Fix perf_mmap() refcount bug found by Syzkaller

 - Fix __perf_event_overflow() vs perf_remove_from_context() race

* tag 'perf-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Fix __perf_event_overflow() vs perf_remove_from_context() race
  perf/core: Fix refcount bug and potential UAF in perf_mmap
  perf/x86/intel/uncore: Add per-scheduler IMC CAS count events
  perf/core: Fix invalid wait context in ctx_sched_in()
2026-03-01 11:07:20 -08:00
Linus Torvalds
b410220870 Now that LLVM 22 has been released officially, require a release
version to use the new CONFIG_WARN_CONTEXT_ANALYSIS feature.
 
 In particular this avoids the widely used Android clang 22.0.1
 pre-release build which is known to be broken for this usecase.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fix from Ingo Molnar:
 "Now that LLVM 22 has been released officially, require a release
  version to use the new CONFIG_WARN_CONTEXT_ANALYSIS feature.

  In particular this avoids the widely used Android clang 22.0.1
  pre-release build which is known to be broken for this usecase"

* tag 'locking-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lib/Kconfig.debug: Require a release version of LLVM 22 for context analysis
2026-03-01 11:00:43 -08:00
Linus Torvalds
afa844360b Miscellaneous irqchip driver fixes:
- Fix frozen interrupt bug in the sifive-plic driver
 
  - Limit per-device MSI interrupts on uncommon gic-v3-its
    hardware variants
 
  - Address Sparse warning by constifying a variable in
    the MMP driver
 
  - Revert broken commit and also fix an error check
    in the ls-extirq driver
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'irq-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irqchip driver fixes from Ingo Molnar:

 - Fix frozen interrupt bug in the sifive-plic driver

 - Limit per-device MSI interrupts on uncommon gic-v3-its hardware
   variants

 - Address Sparse warning by constifying a variable in the MMP driver

 - Revert broken commit and also fix an error check in the ls-extirq
   driver

* tag 'irq-urgent-2026-03-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/ls-extirq: Fix devm_of_iomap() error check
  Revert "irqchip/ls-extirq: Use for_each_of_imap_item iterator"
  irqchip/mmp: Make icu_irq_chip variable static const
  irqchip/gic-v3-its: Limit number of per-device MSIs to the range the ITS supports
  irqchip/sifive-plic: Fix frozen interrupt due to affinity setting
2026-03-01 10:58:16 -08:00
Linus Torvalds
39c6332614 SCSI fixes on 20260228
All changes in drivers (well technically ses is enclosure services,
 but its change is minor).  The biggest is the write combining change
 in lpfc followed by the additional NULL checks in mpi3mr.
 
 Signed-off-by: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
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Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI fixes from James Bottomley:
 "All changes in drivers (well technically SES is enclosure services,
  but its change is minor). The biggest is the write combining change in
  lpfc followed by the additional NULL checks in mpi3mr"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: ufs: core: Fix shift out of bounds when MAXQ=32
  scsi: ufs: core: Move link recovery for hibern8 exit failure to wl_resume
  scsi: ufs: core: Fix possible NULL pointer dereference in ufshcd_add_command_trace()
  scsi: snic: MAINTAINERS: Update snic maintainers
  scsi: snic: Remove unused linkstatus
  scsi: pm8001: Fix use-after-free in pm8001_queue_command()
  scsi: mpi3mr: Add NULL checks when resetting request and reply queues
  scsi: ufs: core: Reset urgent_bkops_lvl to allow runtime PM power mode
  scsi: ses: Fix devices attaching to different hosts
  scsi: ufs: core: Fix RPMB region size detection for UFS 2.2
  scsi: storvsc: Fix scheduling while atomic on PREEMPT_RT
  scsi: lpfc: Properly set WC for DPP mapping
2026-03-01 09:59:29 -08:00
Linus Torvalds
eb71ab2bf7 bpf-fixes
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Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Pull bpf fixes from Alexei Starovoitov:

 - Fix alignment of arm64 JIT buffer to prevent atomic tearing (Fuad
   Tabba)

 - Fix invariant violation for single value tnums in the verifier
   (Harishankar Vishwanathan, Paul Chaignon)

 - Fix a bunch of issues found by ASAN in selftests/bpf (Ihor Solodrai)

 - Fix race in devmpa and cpumap on PREEMPT_RT (Jiayuan Chen)

 - Fix show_fdinfo of kprobe_multi when cookies are not present (Jiri
   Olsa)

 - Fix race in freeing special fields in BPF maps to prevent memory
   leaks (Kumar Kartikeya Dwivedi)

 - Fix OOB read in dmabuf_collector (T.J. Mercier)

* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf: (36 commits)
  selftests/bpf: Avoid simplification of crafted bounds test
  selftests/bpf: Test refinement of single-value tnum
  bpf: Improve bounds when tnum has a single possible value
  bpf: Introduce tnum_step to step through tnum's members
  bpf: Fix race in devmap on PREEMPT_RT
  bpf: Fix race in cpumap on PREEMPT_RT
  selftests/bpf: Add tests for special fields races
  bpf: Retire rcu_trace_implies_rcu_gp() from local storage
  bpf: Delay freeing fields in local storage
  bpf: Lose const-ness of map in map_check_btf()
  bpf: Register dtor for freeing special fields
  selftests/bpf: Fix OOB read in dmabuf_collector
  selftests/bpf: Fix a memory leak in xdp_flowtable test
  bpf: Fix stack-out-of-bounds write in devmap
  bpf: Fix kprobe_multi cookies access in show_fdinfo callback
  bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
  selftests/bpf: Don't override SIGSEGV handler with ASAN
  selftests/bpf: Check BPFTOOL env var in detect_bpftool_path()
  selftests/bpf: Fix out-of-bounds array access bugs reported by ASAN
  selftests/bpf: Fix array bounds warning in jit_disasm_helpers
  ...
2026-02-28 19:54:28 -08:00
Linus Torvalds
63a43faf6a Driver core fixes for 7.0-rc2
- Do not register imx_clk_scu_driver in imx8qxp_clk_probe(); besides
   fixing two other issues, this avoids a deadlock in combination with
   commit dc23806a7c ("driver core: enforce device_lock for
   driver_match_device()").
 
 - Move secondary node lookup from device_get_next_child_node() to
   fwnode_get_next_child_node(); this avoids issues when users switch
   from the device API to the fwnode API.
 
 - Export io_define_{read,write}!() to avoid unused import warnings when
   CONFIG_PCI=n.
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Merge tag 'driver-core-7.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core

Pull driver core fixes from Danilo Krummrich:

 - Do not register imx_clk_scu_driver in imx8qxp_clk_probe(); besides
   fixing two other issues, this avoids a deadlock in combination with
   commit dc23806a7c ("driver core: enforce device_lock for
   driver_match_device()")

 - Move secondary node lookup from device_get_next_child_node() to
   fwnode_get_next_child_node(); this avoids issues when users switch
   from the device API to the fwnode API

 - Export io_define_{read,write}!() to avoid unused import warnings when
   CONFIG_PCI=n

* tag 'driver-core-7.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core:
  clk: scu/imx8qxp: do not register driver in probe()
  rust: io: macro_export io_define_read!() and io_define_write!()
  device property: Allow secondary lookup in fwnode_get_next_child_node()
2026-02-28 19:35:30 -08:00
Linus Torvalds
42eb017830 five client changesets
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Merge tag 'v7.0rc1-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull smb client fixes from Steve French:

 - Two multichannel fixes

 - Locking fix for superblock flags

 - Fix to remove debug message that could log password

 - Cleanup fix for setting credentials

* tag 'v7.0rc1-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  smb: client: Use snprintf in cifs_set_cifscreds
  smb: client: Don't log plaintext credentials in cifs_set_cifscreds
  smb: client: fix broken multichannel with krb5+signing
  smb: client: use atomic_t for mnt_cifs_flags
  smb: client: fix cifs_pick_channel when channels are equally loaded
2026-02-28 10:45:56 -08:00
Takashi Sakamoto
9197e5949a firewire: ohci: initialize page array to use alloc_pages_bulk() correctly
The call of alloc_pages_bulk() skips to fill entries of page array when
the entries already have values. While, 1394 OHCI PCI driver passes the
page array without initializing. It could cause invalid state at PFN
validation in vmap().

Fixes: f2ae92780a ("firewire: ohci: split page allocation from dma mapping")
Reported-by: John Ogness <john.ogness@linutronix.de>
Reported-and-tested-by: Harald Arnesen <linux@skogtun.org>
Reported-and-tested-by: David Gow <david@davidgow.net>
Closes: https://lore.kernel.org/lkml/87tsv1vig5.fsf@jogness.linutronix.de/
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-02-28 10:09:24 -08:00
Linus Torvalds
2f9339c052 spi: Fixes for v7.0
One fix for the stm32 driver which got broken for DMA chaining cases,
 plus a removal of some straggling bindings for the Bikal SoC which has
 been pulled out of the kernel.
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Merge tag 'spi-fix-v7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi

Pull spi fixes from Mark Brown:
 "One fix for the stm32 driver which got broken for DMA chaining cases,
  plus a removal of some straggling bindings for the Bikal SoC which has
  been pulled out of the kernel"

* tag 'spi-fix-v7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: stm32: fix missing pointer assignment in case of dma chaining
  spi: dt-bindings: snps,dw-abp-ssi: Remove unused bindings
2026-02-28 09:21:18 -08:00
Linus Torvalds
463e133751 regulator: Fixes for v7.0
A small pile of fixes, none of which are super major - the code fixes
 are improved error handling and fixing a leak of a device node.  We also
 have a typo fix and an improvement to make the binding example for
 mt6359 more directly usable.
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Merge tag 'regulator-fix-v7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator

Pull regulator fixes from Mark Brown:
 "A small pile of fixes, none of which are super major - the code fixes
  are improved error handling and fixing a leak of a device node.

  We also have a typo fix and an improvement to make the binding example
  for mt6359 more directly usable"

* tag 'regulator-fix-v7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
  regulator: Kconfig: fix a typo
  regulator: bq257xx: Fix device node reference leak in bq257xx_reg_dt_parse_gpio()
  regulator: fp9931: Fix PM runtime reference leak in fp9931_hwmon_read()
  regulator: tps65185: check devm_kzalloc() result in probe
  regulator: dt-bindings: mt6359: make regulator names unique
2026-02-28 09:18:02 -08:00
Linus Torvalds
201795a1b7 s390 updates for 7.0-rc2
- Fix guest pfault init to pass a physical address to DIAG 0x258,
   restoring pfault interrupts and avoiding vCPU stalls during host page-in
 
 - Fix kexec/kdump hangs with stack protector by marking
   s390_reset_system() __no_stack_protector; set_prefix(0) switches
   lowcore and the canary no longer matches
 
 - Fix idle/vtime cputime accounting (idle-exit ordering, vtimer
   double-forwarding) and small cleanups
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Merge tag 's390-7.0-3' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 fixes from Vasily Gorbik:

 - Fix guest pfault init to pass a physical address to DIAG 0x258,
   restoring pfault interrupts and avoiding vCPU stalls during host
   page-in

 - Fix kexec/kdump hangs with stack protector by marking
   s390_reset_system() __no_stack_protector; set_prefix(0) switches
   lowcore and the canary no longer matches

 - Fix idle/vtime cputime accounting (idle-exit ordering, vtimer
   double-forwarding) and small cleanups

* tag 's390-7.0-3' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/pfault: Fix virtual vs physical address confusion
  s390/kexec: Disable stack protector in s390_reset_system()
  s390/idle: Remove psw_idle() prototype
  s390/vtime: Use lockdep_assert_irqs_disabled() instead of BUG_ON()
  s390/vtime: Use __this_cpu_read() / get rid of READ_ONCE()
  s390/irq/idle: Remove psw bits early
  s390/idle: Inline update_timer_idle()
  s390/idle: Slightly optimize idle time accounting
  s390/idle: Add comment for non obvious code
  s390/vtime: Fix virtual timer forwarding
  s390/idle: Fix cpu idle exit cpu time accounting
2026-02-28 09:01:33 -08:00
Paolo Bonzini
55365ab85a KVM/arm64 fixes for 7.0, take #1
- Make sure we don't leak any S1POE state from guest to guest when
   the feature is supported on the HW, but not enabled on the host
 
 - Propagate the ID registers from the host into non-protected VMs
   managed by pKVM, ensuring that the guest sees the intended feature set
 
 - Drop double kern_hyp_va() from unpin_host_sve_state(), which could
   bite us if we were to change kern_hyp_va() to not being idempotent
 
 - Don't leak stage-2 mappings in protected mode
 
 - Correctly align the faulting address when dealing with single page
   stage-2 mappings for PAGE_SIZE > 4kB
 
 - Fix detection of virtualisation-capable GICv5 IRS, due to the
   maintainer being obviously fat fingered...
 
 - Remove duplication of code retrieving the ASID for the purpose of
   S1 PT handling
 
 - Fix slightly abusive const-ification in vgic_set_kvm_info()
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Merge tag 'kvmarm-fixes-7.0-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 7.0, take #1

- Make sure we don't leak any S1POE state from guest to guest when
  the feature is supported on the HW, but not enabled on the host

- Propagate the ID registers from the host into non-protected VMs
  managed by pKVM, ensuring that the guest sees the intended feature set

- Drop double kern_hyp_va() from unpin_host_sve_state(), which could
  bite us if we were to change kern_hyp_va() to not being idempotent

- Don't leak stage-2 mappings in protected mode

- Correctly align the faulting address when dealing with single page
  stage-2 mappings for PAGE_SIZE > 4kB

- Fix detection of virtualisation-capable GICv5 IRS, due to the
  maintainer being obviously fat fingered...

- Remove duplication of code retrieving the ASID for the purpose of
  S1 PT handling

- Fix slightly abusive const-ification in vgic_set_kvm_info()
2026-02-28 15:33:34 +01:00
Paolo Bonzini
70295a479d KVM: always define KVM_CAP_SYNC_MMU
KVM_CAP_SYNC_MMU is provided by KVM's MMU notifiers, which are now always
available.  Move the definition from individual architectures to common
code.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2026-02-28 15:31:35 +01:00
Paolo Bonzini
407fd8b8d8 KVM: remove CONFIG_KVM_GENERIC_MMU_NOTIFIER
All architectures now use MMU notifier for KVM page table management.
Remove the Kconfig symbol and the code that is used when it is
disabled.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2026-02-28 15:31:35 +01:00
Alexei Starovoitov
b9c0a5c483 Merge branch 'fix-invariant-violation-for-single-value-tnums'
Paul Chaignon says:

====================
Fix invariant violation for single-value tnums

We're hitting an invariant violation in Cilium that sometimes leads to
BPF programs being rejected and Cilium failing to start [1]. As far as
I know this is the first case of invariant violation found in a real
program (i.e., not by a fuzzer). The following extract from verifier
logs shows what's happening:

  from 201 to 236: R1=0 R6=ctx() R7=1 R9=scalar(smin=umin=smin32=umin32=3584,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100)) R10=fp0
  236: R1=0 R6=ctx() R7=1 R9=scalar(smin=umin=smin32=umin32=3584,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100)) R10=fp0
  ; if (magic == MARK_MAGIC_HOST || magic == MARK_MAGIC_OVERLAY || magic == MARK_MAGIC_ENCRYPT) @ bpf_host.c:1337
  236: (16) if w9 == 0xe00 goto pc+45   ; R9=scalar(smin=umin=smin32=umin32=3585,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100))
  237: (16) if w9 == 0xf00 goto pc+1
  verifier bug: REG INVARIANTS VIOLATION (false_reg1): range bounds violation u64=[0xe01, 0xe00] s64=[0xe01, 0xe00] u32=[0xe01, 0xe00] s32=[0xe01, 0xe00] var_off=(0xe00, 0x0)

More details are given in the second patch, but in short, the verifier
should be able to detect that the false branch of instruction 237 is
never true. After instruction 236, the u64 range and the tnum overlap
in a single value, 0xf00.

The long-term solution to invariant violation is likely to rely on the
refinement + invariant violation check to detect dead branches, as
started by Eduard. To fix the current issue, we need something with
less refactoring that we can backport to affected kernels.

The solution implemented in the second patch is to improve the bounds
refinement to avoid this case. It relies on a new tnum helper,
tnum_step, first sent as an RFC in [2]. The last two patches extend and
update the selftests.

Link: https://github.com/cilium/cilium/issues/44216 [1]
Link: https://lore.kernel.org/bpf/20251107192328.2190680-2-harishankar.vishwanathan@gmail.com/ [2]

Changes in v3:
  - Fix commit description error spotted by AI bot.
  - Simplify constants in first two tests (Eduard).
  - Rework comment on third test (Eduard).
  - Add two new negative test cases (Eduard).
  - Rebased.
Changes in v2:
  - Add guard suggested by Hari in tnum_step, to avoid undefined
    behavior spotted by AI code review.
  - Add explanation diagrams in code as suggested by Eduard.
  - Rework conditions for readability as suggested by Eduard.
  - Updated reference to SMT formula.
  - Rebased.
====================

Link: https://patch.msgid.link/cover.1772225741.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 16:11:50 -08:00
Paul Chaignon
024cea2d64 selftests/bpf: Avoid simplification of crafted bounds test
The reg_bounds_crafted tests validate the verifier's range analysis
logic. They focus on the actual ranges and thus ignore the tnum. As a
consequence, they carry the assumption that the tested cases can be
reproduced in userspace without using the tnum information.

Unfortunately, the previous change the refinement logic breaks that
assumption for one test case:

  (u64)2147483648 (u32)<op> [4294967294; 0x100000000]

The tested bytecode is shown below. Without our previous improvement, on
the false branch of the condition, R7 is only known to have u64 range
[0xfffffffe; 0x100000000]. With our improvement, and using the tnum
information, we can deduce that R7 equals 0x100000000.

  19: (bc) w0 = w6                ; R6=0x80000000
  20: (bc) w0 = w7                ; R7=scalar(smin=umin=0xfffffffe,smax=umax=0x100000000,smin32=-2,smax32=0,var_off=(0x0; 0x1ffffffff))
  21: (be) if w6 <= w7 goto pc+3  ; R6=0x80000000 R7=0x100000000

R7's tnum is (0; 0x1ffffffff). On the false branch, regs_refine_cond_op
refines R7's u32 range to [0; 0x7fffffff]. Then, __reg32_deduce_bounds
refines the s32 range to 0 using u32 and finally also sets u32=0.
From this, __reg_bound_offset improves the tnum to (0; 0x100000000).
Finally, our previous patch uses this new tnum to deduce that it only
intersect with u64=[0xfffffffe; 0x100000000] in a single value:
0x100000000.

Because the verifier uses the tnum to reach this constant value, the
selftest is unable to reproduce it by only simulating ranges. The
solution implemented in this patch is to change the test case such that
there is more than one overlap value between u64 and the tnum. The max.
u64 value is thus changed from 0x100000000 to 0x300000000.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/50641c6a7ef39520595dcafa605692427c1006ec.1772225741.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 16:11:50 -08:00
Paul Chaignon
e6ad477d1b selftests/bpf: Test refinement of single-value tnum
This patch introduces selftests to cover the new bounds refinement
logic introduced in the previous patch. Without the previous patch,
the first two tests fail because of the invariant violation they
trigger. The last test fails because the R10 access is not detected as
dead code. In addition, all three tests fail because of R0 having a
non-constant value in the verifier logs.

In addition, the last two cases are covering the negative cases: when we
shouldn't refine the bounds because the u64 and tnum overlap in at least
two values.

Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/90d880c8cf587b9f7dc715d8961cd1b8111d01a8.1772225741.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 16:11:50 -08:00
Paul Chaignon
efc11a6678 bpf: Improve bounds when tnum has a single possible value
We're hitting an invariant violation in Cilium that sometimes leads to
BPF programs being rejected and Cilium failing to start [1]. The
following extract from verifier logs shows what's happening:

  from 201 to 236: R1=0 R6=ctx() R7=1 R9=scalar(smin=umin=smin32=umin32=3584,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100)) R10=fp0
  236: R1=0 R6=ctx() R7=1 R9=scalar(smin=umin=smin32=umin32=3584,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100)) R10=fp0
  ; if (magic == MARK_MAGIC_HOST || magic == MARK_MAGIC_OVERLAY || magic == MARK_MAGIC_ENCRYPT) @ bpf_host.c:1337
  236: (16) if w9 == 0xe00 goto pc+45   ; R9=scalar(smin=umin=smin32=umin32=3585,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100))
  237: (16) if w9 == 0xf00 goto pc+1
  verifier bug: REG INVARIANTS VIOLATION (false_reg1): range bounds violation u64=[0xe01, 0xe00] s64=[0xe01, 0xe00] u32=[0xe01, 0xe00] s32=[0xe01, 0xe00] var_off=(0xe00, 0x0)

We reach instruction 236 with two possible values for R9, 0xe00 and
0xf00. This is perfectly reflected in the tnum, but of course the ranges
are less accurate and cover [0xe00; 0xf00]. Taking the fallthrough path
at instruction 236 allows the verifier to reduce the range to
[0xe01; 0xf00]. The tnum is however not updated.

With these ranges, at instruction 237, the verifier is not able to
deduce that R9 is always equal to 0xf00. Hence the fallthrough pass is
explored first, the verifier refines the bounds using the assumption
that R9 != 0xf00, and ends up with an invariant violation.

This pattern of impossible branch + bounds refinement is common to all
invariant violations seen so far. The long-term solution is likely to
rely on the refinement + invariant violation check to detect dead
branches, as started by Eduard. To fix the current issue, we need
something with less refactoring that we can backport.

This patch uses the tnum_step helper introduced in the previous patch to
detect the above situation. In particular, three cases are now detected
in the bounds refinement:

1. The u64 range and the tnum only overlap in umin.
   u64:  ---[xxxxxx]-----
   tnum: --xx----------x-

2. The u64 range and the tnum only overlap in the maximum value
   represented by the tnum, called tmax.
   u64:  ---[xxxxxx]-----
   tnum: xx-----x--------

3. The u64 range and the tnum only overlap in between umin (excluded)
   and umax.
   u64:  ---[xxxxxx]-----
   tnum: xx----x-------x-

To detect these three cases, we call tnum_step(tnum, umin), which
returns the smallest member of the tnum greater than umin, called
tnum_next here. We're in case (1) if umin is part of the tnum and
tnum_next is greater than umax. We're in case (2) if umin is not part of
the tnum and tnum_next is equal to tmax. Finally, we're in case (3) if
umin is not part of the tnum, tnum_next is inferior or equal to umax,
and calling tnum_step a second time gives us a value past umax.

This change implements these three cases. With it, the above bytecode
looks as follows:

  0: (85) call bpf_get_prandom_u32#7    ; R0=scalar()
  1: (47) r0 |= 3584                    ; R0=scalar(smin=0x8000000000000e00,umin=umin32=3584,smin32=0x80000e00,var_off=(0xe00; 0xfffffffffffff1ff))
  2: (57) r0 &= 3840                    ; R0=scalar(smin=umin=smin32=umin32=3584,smax=umax=smax32=umax32=3840,var_off=(0xe00; 0x100))
  3: (15) if r0 == 0xe00 goto pc+2      ; R0=3840
  4: (15) if r0 == 0xf00 goto pc+1
  4: R0=3840
  6: (95) exit

In addition to the new selftests, this change was also verified with
Agni [3]. For the record, the raw SMT is available at [4]. The property
it verifies is that: If a concrete value x is contained in all input
abstract values, after __update_reg_bounds, it will continue to be
contained in all output abstract values.

Link: https://github.com/cilium/cilium/issues/44216 [1]
Link: https://pchaigno.github.io/test-verifier-complexity.html [2]
Link: https://github.com/bpfverif/agni [3]
Link: https://pastebin.com/raw/naCfaqNx [4]
Fixes: 0df1a55afa ("bpf: Warn on internal verifier errors")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Tested-by: Marco Schirrmeister <mschirrmeister@gmail.com>
Co-developed-by: Harishankar Vishwanathan <harishankar.vishwanathan@gmail.com>
Signed-off-by: Harishankar Vishwanathan <harishankar.vishwanathan@gmail.com>
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/ef254c4f68be19bd393d450188946821c588565d.1772225741.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 16:11:50 -08:00
Harishankar Vishwanathan
76e954155b bpf: Introduce tnum_step to step through tnum's members
This commit introduces tnum_step(), a function that, when given t, and a
number z returns the smallest member of t larger than z. The number z
must be greater or equal to the smallest member of t and less than the
largest member of t.

The first step is to compute j, a number that keeps all of t's known
bits, and matches all unknown bits to z's bits. Since j is a member of
the t, it is already a candidate for result. However, we want our result
to be (minimally) greater than z.

There are only two possible cases:

(1) Case j <= z. In this case, we want to increase the value of j and
make it > z.
(2) Case j > z. In this case, we want to decrease the value of j while
keeping it > z.

(Case 1) j <= z

t = xx11x0x0
z = 10111101 (189)
j = 10111000 (184)
         ^
         k

(Case 1.1) Let's first consider the case where j < z. We will address j
== z later.

Since z > j, there had to be a bit position that was 1 in z and a 0 in
j, beyond which all positions of higher significance are equal in j and
z. Further, this position could not have been unknown in a, because the
unknown positions of a match z. This position had to be a 1 in z and
known 0 in t.

Let k be position of the most significant 1-to-0 flip. In our example, k
= 3 (starting the count at 1 at the least significant bit).  Setting (to
1) the unknown bits of t in positions of significance smaller than
k will not produce a result > z. Hence, we must set/unset the unknown
bits at positions of significance higher than k. Specifically, we look
for the next larger combination of 1s and 0s to place in those
positions, relative to the combination that exists in z. We can achieve
this by concatenating bits at unknown positions of t into an integer,
adding 1, and writing the bits of that result back into the
corresponding bit positions previously extracted from z.

>From our example, considering only positions of significance greater
than k:

t =  xx..x
z =  10..1
    +    1
     -----
     11..0

This is the exact combination 1s and 0s we need at the unknown bits of t
in positions of significance greater than k. Further, our result must
only increase the value minimally above z. Hence, unknown bits in
positions of significance smaller than k should remain 0. We finally
have,

result = 11110000 (240)

(Case 1.2) Now consider the case when j = z, for example

t = 1x1x0xxx
z = 10110100 (180)
j = 10110100 (180)

Matching the unknown bits of the t to the bits of z yielded exactly z.
To produce a number greater than z, we must set/unset the unknown bits
in t, and *all* the unknown bits of t candidates for being set/unset. We
can do this similar to Case 1.1, by adding 1 to the bits extracted from
the masked bit positions of z. Essentially, this case is equivalent to
Case 1.1, with k = 0.

t =  1x1x0xxx
z =  .0.1.100
    +       1
    ---------
     .0.1.101

This is the exact combination of bits needed in the unknown positions of
t. After recalling the known positions of t, we get

result = 10110101 (181)

(Case 2) j > z

t = x00010x1
z = 10000010 (130)
j = 10001011 (139)
	^
	k

Since j > z, there had to be a bit position which was 0 in z, and a 1 in
j, beyond which all positions of higher significance are equal in j and
z. This position had to be a 0 in z and known 1 in t. Let k be the
position of the most significant 0-to-1 flip. In our example, k = 4.

Because of the 0-to-1 flip at position k, a member of t can become
greater than z if the bits in positions greater than k are themselves >=
to z. To make that member *minimally* greater than z, the bits in
positions greater than k must be exactly = z. Hence, we simply match all
of t's unknown bits in positions more significant than k to z's bits. In
positions less significant than k, we set all t's unknown bits to 0
to retain minimality.

In our example, in positions of greater significance than k (=4),
t=x000. These positions are matched with z (1000) to produce 1000. In
positions of lower significance than k, t=10x1. All unknown bits are set
to 0 to produce 1001. The final result is:

result = 10001001 (137)

This concludes the computation for a result > z that is a member of t.

The procedure for tnum_step() in this commit implements the idea
described above. As a proof of correctness, we verified the algorithm
against a logical specification of tnum_step. The specification asserts
the following about the inputs t, z and output res that:

1. res is a member of t, and
2. res is strictly greater than z, and
3. there does not exist another value res2 such that
	3a. res2 is also a member of t, and
	3b. res2 is greater than z
	3c. res2 is smaller than res

We checked the implementation against this logical specification using
an SMT solver. The verification formula in SMTLIB format is available
at [1]. The verification returned an "unsat": indicating that no input
assignment exists for which the implementation and the specification
produce different outputs.

In addition, we also automatically generated the logical encoding of the
C implementation using Agni [2] and verified it against the same
specification. This verification also returned an "unsat", confirming
that the implementation is equivalent to the specification. The formula
for this check is also available at [3].

Link: https://pastebin.com/raw/2eRWbiit [1]
Link: https://github.com/bpfverif/agni [2]
Link: https://pastebin.com/raw/EztVbBJ2 [3]
Co-developed-by: Srinivas Narayana <srinivas.narayana@rutgers.edu>
Signed-off-by: Srinivas Narayana <srinivas.narayana@rutgers.edu>
Co-developed-by: Santosh Nagarakatte <santosh.nagarakatte@rutgers.edu>
Signed-off-by: Santosh Nagarakatte <santosh.nagarakatte@rutgers.edu>
Signed-off-by: Harishankar Vishwanathan <harishankar.vishwanathan@gmail.com>
Link: https://lore.kernel.org/r/93fdf71910411c0f19e282ba6d03b4c65f9c5d73.1772225741.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 16:11:50 -08:00
Alexei Starovoitov
8c0d9e178d Merge branch 'bpf-cpumap-devmap-fix-per-cpu-bulk-queue-races-on-preempt_rt'
Jiayuan Chen says:

====================
bpf: Fix per-CPU bulk queue races on PREEMPT_RT

On PREEMPT_RT kernels, local_bh_disable() only calls migrate_disable()
(when PREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable
preemption. This means CFS scheduling can preempt a task inside the
per-CPU bulk queue (bq) operations in cpumap and devmap, allowing
another task on the same CPU to concurrently access the same bq,
leading to use-after-free, list corruption, and kernel panics.

Patch 1 fixes the cpumap race in bq_flush_to_queue(), originally
reported by syzbot [1].

Patch 2 fixes the same class of race in devmap's bq_xmit_all(),
identified by code inspection after Sebastian Andrzej Siewior pointed
out that devmap has the same per-CPU bulk queue pattern [2].

Both patches use local_lock_nested_bh() to serialize access to the
per-CPU bq. On non-RT this is a pure lockdep annotation with no
overhead; on PREEMPT_RT it provides a per-CPU sleeping lock.

To reproduce the devmap race, insert an mdelay(100) in bq_xmit_all()
after "cnt = bq->count" and before the actual transmit loop. Then pin
two threads to the same CPU, each running BPF_PROG_TEST_RUN with an XDP
program that redirects to a DEVMAP entry (e.g. a veth pair). CFS
timeslicing during the mdelay window causes interleaving. Without the
fix, KASAN reports null-ptr-deref due to operating on freed frames:

  BUG: KASAN: null-ptr-deref in __build_skb_around+0x22d/0x340
  Write of size 32 at addr 0000000000000d50 by task devmap_race_rep/449

  CPU: 0 UID: 0 PID: 449 Comm: devmap_race_rep Not tainted 6.19.0+ #31 PREEMPT_RT
  Call Trace:
   <TASK>
   __build_skb_around+0x22d/0x340
   build_skb_around+0x25/0x260
   __xdp_build_skb_from_frame+0x103/0x860
   veth_xdp_rcv_bulk_skb.isra.0+0x162/0x320
   veth_xdp_rcv.constprop.0+0x61e/0xbb0
   veth_poll+0x280/0xb50
   __napi_poll.constprop.0+0xa5/0x590
   net_rx_action+0x4b0/0xea0
   handle_softirqs.isra.0+0x1b3/0x780
   __local_bh_enable_ip+0x12a/0x240
   xdp_test_run_batch.constprop.0+0xedd/0x1f60
   bpf_test_run_xdp_live+0x304/0x640
   bpf_prog_test_run_xdp+0xd24/0x1b70
   __sys_bpf+0x61c/0x3e00
   </TASK>

  Kernel panic - not syncing: Fatal exception in interrupt

[1] https://lore.kernel.org/all/69369331.a70a0220.38f243.009d.GAE@google.com/T/
[2] https://lore.kernel.org/bpf/20260212023634.366343-1-jiayuan.chen@linux.dev/

v3 -> v4: https://lore.kernel.org/all/20260213034018.284146-1-jiayuan.chen@linux.dev/
- Move panic trace to cover letter. (Sebastian Andrzej Siewior)
- Add Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> to both patches
  from cover letter.

v2 -> v3: https://lore.kernel.org/bpf/20260212023634.366343-1-jiayuan.chen@linux.dev/
- Fix commit message: remove incorrect "spin_lock() becomes rt_mutex"
claim, the per-CPU bq has no spin_lock at all. (Sebastian Andrzej Siewior)
- Fix commit message: accurately describe local_lock_nested_bh()
behavior instead of referencing local_lock(). (Sebastian Andrzej Siewior)
- Remove incomplete discussion of snapshot alternative.
(Sebastian Andrzej Siewior)
- Remove panic trace from commit message. (Sebastian Andrzej Siewior)
- Add patch 2/2 for devmap, same race pattern. (Sebastian Andrzej Siewior)

v1 -> v2: https://lore.kernel.org/bpf/20260211064417.196401-1-jiayuan.chen@linux.dev/
- Use local_lock_nested_bh()/local_unlock_nested_bh() instead of
local_lock()/local_unlock(), since these paths already run under
local_bh_disable(). (Sebastian Andrzej Siewior)
- Replace "Caller must hold bq->bq_lock" comment with
lockdep_assert_held() in bq_flush_to_queue(). (Sebastian Andrzej Siewior)
- Fix Fixes tag to 3253cb49cb ("softirq: Allow to drop the
softirq-BKL lock on PREEMPT_RT") which is the actual commit that
makes the race possible. (Sebastian Andrzej Siewior)
====================

Link: https://patch.msgid.link/20260225121459.183121-1-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 16:08:34 -08:00
Jiayuan Chen
1872e75375 bpf: Fix race in devmap on PREEMPT_RT
On PREEMPT_RT kernels, the per-CPU xdp_dev_bulk_queue (bq) can be
accessed concurrently by multiple preemptible tasks on the same CPU.

The original code assumes bq_enqueue() and __dev_flush() run atomically
with respect to each other on the same CPU, relying on
local_bh_disable() to prevent preemption. However, on PREEMPT_RT,
local_bh_disable() only calls migrate_disable() (when
PREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable
preemption, which allows CFS scheduling to preempt a task during
bq_xmit_all(), enabling another task on the same CPU to enter
bq_enqueue() and operate on the same per-CPU bq concurrently.

This leads to several races:

1. Double-free / use-after-free on bq->q[]: bq_xmit_all() snapshots
   cnt = bq->count, then iterates bq->q[0..cnt-1] to transmit frames.
   If preempted after the snapshot, a second task can call bq_enqueue()
   -> bq_xmit_all() on the same bq, transmitting (and freeing) the
   same frames. When the first task resumes, it operates on stale
   pointers in bq->q[], causing use-after-free.

2. bq->count and bq->q[] corruption: concurrent bq_enqueue() modifying
   bq->count and bq->q[] while bq_xmit_all() is reading them.

3. dev_rx/xdp_prog teardown race: __dev_flush() clears bq->dev_rx and
   bq->xdp_prog after bq_xmit_all(). If preempted between
   bq_xmit_all() return and bq->dev_rx = NULL, a preempting
   bq_enqueue() sees dev_rx still set (non-NULL), skips adding bq to
   the flush_list, and enqueues a frame. When __dev_flush() resumes,
   it clears dev_rx and removes bq from the flush_list, orphaning the
   newly enqueued frame.

4. __list_del_clearprev() on flush_node: similar to the cpumap race,
   both tasks can call __list_del_clearprev() on the same flush_node,
   the second dereferences the prev pointer already set to NULL.

The race between task A (__dev_flush -> bq_xmit_all) and task B
(bq_enqueue -> bq_xmit_all) on the same CPU:

  Task A (xdp_do_flush)          Task B (ndo_xdp_xmit redirect)
  ----------------------         --------------------------------
  __dev_flush(flush_list)
    bq_xmit_all(bq)
      cnt = bq->count  /* e.g. 16 */
      /* start iterating bq->q[] */
    <-- CFS preempts Task A -->
                                   bq_enqueue(dev, xdpf)
                                     bq->count == DEV_MAP_BULK_SIZE
                                     bq_xmit_all(bq, 0)
                                       cnt = bq->count  /* same 16! */
                                       ndo_xdp_xmit(bq->q[])
                                       /* frames freed by driver */
                                       bq->count = 0
    <-- Task A resumes -->
      ndo_xdp_xmit(bq->q[])
      /* use-after-free: frames already freed! */

Fix this by adding a local_lock_t to xdp_dev_bulk_queue and acquiring
it in bq_enqueue() and __dev_flush(). These paths already run under
local_bh_disable(), so use local_lock_nested_bh() which on non-RT is
a pure annotation with no overhead, and on PREEMPT_RT provides a
per-CPU sleeping lock that serializes access to the bq.

Fixes: 3253cb49cb ("softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT")
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://lore.kernel.org/r/20260225121459.183121-3-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 16:08:10 -08:00
Jiayuan Chen
869c63d597 bpf: Fix race in cpumap on PREEMPT_RT
On PREEMPT_RT kernels, the per-CPU xdp_bulk_queue (bq) can be accessed
concurrently by multiple preemptible tasks on the same CPU.

The original code assumes bq_enqueue() and __cpu_map_flush() run
atomically with respect to each other on the same CPU, relying on
local_bh_disable() to prevent preemption. However, on PREEMPT_RT,
local_bh_disable() only calls migrate_disable() (when
PREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable
preemption, which allows CFS scheduling to preempt a task during
bq_flush_to_queue(), enabling another task on the same CPU to enter
bq_enqueue() and operate on the same per-CPU bq concurrently.

This leads to several races:

1. Double __list_del_clearprev(): after bq->count is reset in
   bq_flush_to_queue(), a preempting task can call bq_enqueue() ->
   bq_flush_to_queue() on the same bq when bq->count reaches
   CPU_MAP_BULK_SIZE. Both tasks then call __list_del_clearprev()
   on the same bq->flush_node, the second call dereferences the
   prev pointer that was already set to NULL by the first.

2. bq->count and bq->q[] races: concurrent bq_enqueue() can corrupt
   the packet queue while bq_flush_to_queue() is processing it.

The race between task A (__cpu_map_flush -> bq_flush_to_queue) and
task B (bq_enqueue -> bq_flush_to_queue) on the same CPU:

  Task A (xdp_do_flush)          Task B (cpu_map_enqueue)
  ----------------------         ------------------------
  bq_flush_to_queue(bq)
    spin_lock(&q->producer_lock)
    /* flush bq->q[] to ptr_ring */
    bq->count = 0
    spin_unlock(&q->producer_lock)
                                   bq_enqueue(rcpu, xdpf)
    <-- CFS preempts Task A -->      bq->q[bq->count++] = xdpf
                                     /* ... more enqueues until full ... */
                                     bq_flush_to_queue(bq)
                                       spin_lock(&q->producer_lock)
                                       /* flush to ptr_ring */
                                       spin_unlock(&q->producer_lock)
                                       __list_del_clearprev(flush_node)
                                         /* sets flush_node.prev = NULL */
    <-- Task A resumes -->
    __list_del_clearprev(flush_node)
      flush_node.prev->next = ...
      /* prev is NULL -> kernel oops */

Fix this by adding a local_lock_t to xdp_bulk_queue and acquiring it
in bq_enqueue() and __cpu_map_flush(). These paths already run under
local_bh_disable(), so use local_lock_nested_bh() which on non-RT is
a pure annotation with no overhead, and on PREEMPT_RT provides a
per-CPU sleeping lock that serializes access to the bq.

To reproduce, insert an mdelay(100) between bq->count = 0 and
__list_del_clearprev() in bq_flush_to_queue(), then run reproducer
provided by syzkaller.

Fixes: 3253cb49cb ("softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT")
Reported-by: syzbot+2b3391f44313b3983e91@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/69369331.a70a0220.38f243.009d.GAE@google.com/T/
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://lore.kernel.org/r/20260225121459.183121-2-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 16:07:14 -08:00
Alexei Starovoitov
5263e30fff Merge branch 'close-race-in-freeing-special-fields-and-map-value'
Kumar Kartikeya Dwivedi says:

====================
Close race in freeing special fields and map value

There exists a race across various map types where the freeing of
special fields (tw, timer, wq, kptr, etc.) can be done eagerly when a
logical delete operation is done on a map value, such that the program
which continues to have access to such a map value can recreate the
fields and cause them to leak.

The set contains fixes for this case. It is a continuation of Mykyta's
previous attempt in [0], but applies to all fields. A test is included
which reproduces the bug reliably in absence of the fixes.

Local Storage Benchmarks
------------------------
Evaluation Setup: Benchmarked on a dual-socket Intel Xeon Gold 6348 (Ice
Lake) @ 2.60GHz (56 cores / 112 threads), with the CPU governor set to
performance. Bench was pinned to a single NUMA node throughout the test.

Benchmark comes from [1] using the following command:
./bench -p 1 local-storage-create --storage-type <socket,task> --batch-size <16,32,64>

Before the test, 10 runs of all cases ([socket|task] x 3 batch sizes x 7
iterations per batch size) are done to warm up and prime the machine.

Then, 3 runs of all cases are done (with and without the patch, across
reboots).

For each comparison, we have 21 samples, i.e. per batch size (e.g.
socket 16) of a given local storage, we have 3 runs x 7 iterations.

The statistics (mean, median, stddev) and t-test is done for each
scenario (local storage and batch size pair) individually (21 samples
for either case). All values are for local storage creations in thousand
creations / sec (k/s).

	       Baseline (without patch)               With patch                       Delta
     Case      Median        Mean   Std. Dev.   Median        Mean   Std. Dev.   Median       %
---------------------------------------------------------------------------------------------------
socket 16     432.026     431.941    1.047     431.347     431.953    1.635      -0.679    -0.16%
socket 32     432.641     432.818    1.535     432.488     432.302    1.508      -0.153    -0.04%
socket 64     431.504     431.996    1.337     429.145     430.326    2.469      -2.359    -0.55%
  task 16      38.816      39.382    1.456      39.657      39.337    1.831      +0.841    +2.17%
  task 32      38.815      39.644    2.690      38.721      39.122    1.636      -0.094    -0.24%
  task 64      37.562      38.080    1.701      39.554      38.563    1.689      +1.992    +5.30%

The cases for socket are within the range of noise, and improvements in task
local storage are due to high variance (CV ~4%-6% across batch sizes). The only
statistically significant case worth mentioning is socket with batch size 64
with p-value from t-test < 0.05, but the absolute difference is small (~2k/s).

TL;DR there doesn't appear to be any significant regression or improvement.

  [0]: https://lore.kernel.org/bpf/20260216131341.1285427-1-mykyta.yatsenko5@gmail.com
  [1]: https://lore.kernel.org/bpf/20260205222916.1788211-1-ameryhung@gmail.com

Changelog:
----------
v2 -> v3
v2: https://lore.kernel.org/bpf/20260227052031.3988575-1-memxor@gmail.com

 * Add syzbot Tested-by.
 * Add Amery's Reviewed-by.
 * Fix missing rcu_dereference_check() in __bpf_selem_free_rcu. (BPF CI Bot)
 * Remove migrate_disable() in bpf_selem_free_rcu. (Alexei)

v1 -> v2
v1: https://lore.kernel.org/bpf/20260225185121.2057388-1-memxor@gmail.com

 * Add Paul's Reviewed-by.
 * Fix use-after-free in accessing bpf_mem_alloc embedded in map. (syzbot CI)
 * Add benchmark numbers for local storage.
 * Add extra test case for per-cpu hashmap coverage with up to 16 refcount leaks.
 * Target bpf tree.
====================

Link: https://patch.msgid.link/20260227224806.646888-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 15:39:01 -08:00
Kumar Kartikeya Dwivedi
2939d7b3b0 selftests/bpf: Add tests for special fields races
Add a couple of tests to ensure that the refcount drops to zero when we
exercise the race where creation of a special field succeeds the logical
bpf_obj_free_fields done when deleting an element. Prior to previous
changes, the fields would be freed eagerly and repopulate and end up
leaking, causing the reference to not drop down correctly. Running this
test on a kernel without fixes will cause a hang in delete_module, since
the module reference stays active due to the leaked kptr not dropping
it. After the fixes tests succeed as expected.

Reviewed-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260227224806.646888-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 15:39:00 -08:00
Kumar Kartikeya Dwivedi
baa35b3cb6 bpf: Retire rcu_trace_implies_rcu_gp() from local storage
This assumption will always hold going forward, hence just remove the
various checks and assume it is true with a comment for the uninformed
reader.

Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260227224806.646888-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 15:39:00 -08:00
Kumar Kartikeya Dwivedi
f41deee082 bpf: Delay freeing fields in local storage
Currently, when use_kmalloc_nolock is false, the freeing of fields for a
local storage selem is done eagerly before waiting for the RCU or RCU
tasks trace grace period to elapse. This opens up a window where the
program which has access to the selem can recreate the fields after the
freeing of fields is done eagerly, causing memory leaks when the element
is finally freed and returned to the kernel.

Make a few changes to address this. First, delay the freeing of fields
until after the grace periods have expired using a __bpf_selem_free_rcu
wrapper which is eventually invoked after transitioning through the
necessary number of grace period waits. Replace usage of the kfree_rcu
with call_rcu to be able to take a custom callback. Finally, care needs
to be taken to extend the rcu barriers for all cases, and not just when
use_kmalloc_nolock is true, as RCU and RCU tasks trace callbacks can be
in flight for either case and access the smap field, which is used to
obtain the BTF record to walk over special fields in the map value.

While we're at it, drop migrate_disable() from bpf_selem_free_rcu, since
migration should be disabled for RCU callbacks already.

Fixes: 9bac675e63 ("bpf: Postpone bpf_obj_free_fields to the rcu callback")
Reviewed-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260227224806.646888-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 15:39:00 -08:00
Kumar Kartikeya Dwivedi
ae51772b1e bpf: Lose const-ness of map in map_check_btf()
BPF hash map may now use the map_check_btf() callback to decide whether
to set a dtor on its bpf_mem_alloc or not. Unlike C++ where members can
opt out of const-ness using mutable, we must lose the const qualifier on
the callback such that we can avoid the ugly cast. Make the change and
adjust all existing users, and lose the comment in hashtab.c.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260227224806.646888-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-27 15:39:00 -08:00