Commit Graph

11492 Commits

Author SHA1 Message Date
Paolo Bonzini
c6e127b88c KVM: s390: Misc fixes for 7.2
Fix a bunch of small issues that came up during the previous round of
 fixes.
 
 They are mostly extremely unlikely races, but they should be fixed
 nonetheless.
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Merge tag 'kvm-s390-master-7.2-3' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: Misc fixes for 7.2

Fix a bunch of small issues that came up during the previous round of
fixes.

They are mostly extremely unlikely races, but they should be fixed
nonetheless.
2026-08-06 15:47:46 +02:00
Claudio Imbrenda
feadc5e84d KVM: s390: Fix cleanup in kvm_s390_pv_create_cpu()
If creating a protected vCPU in kvm_s390_pv_create_cpu() fails,
kvm_s390_pv_destroy_cpu() was called, which checks whether the vCPU has
a PV handle and exits doing nothing otherwise. At that point, due to
not having created the protected vCPU, the PV handle will not be set,
and kvm_s390_pv_destroy_cpu() will do nothing, thus leaking the
allocated memory.

Fix by factoring out the code to free and reset a PV vCPU; call it from
kvm_s390_pv_destroy_cpu() and kvm_s390_pv_create_cpu().

Opportunistically fix the return value of kvm_s390_pv_destroy_cpu() in
case of errors: return -EIO instead if EIO.

Fixes: d4074324b0 ("KVM: s390: pv: avoid double free of sida page")
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-14-imbrenda@linux.ibm.com>
2026-08-03 17:09:46 +02:00
Claudio Imbrenda
9187a9186d KVM: s390: Fix ordering when adding to SCA
When adding a new vCPU to the SCA area, the validity bit in the MCN was
set before the pointer to the state description, potentially allowing
for a race.

Fix by setting the pointer before setting the bit.

Fixes: 14542a0a54 ("KVM: S390: Remove sca_lock")
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-13-imbrenda@linux.ibm.com>
2026-08-03 16:51:34 +02:00
Claudio Imbrenda
216c5289dd KVM: s390: Return -EINTR if a signal is pending while faulting-in
If a fatal signal is pending while trying to fault-in a page, return
-EINTR instead of -EAGAIN.

Also fix unpack_one() to handle -EINTR properly.

Fixes: e907ae5301 ("KVM: s390: Add helper functions for fault handling")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-12-imbrenda@linux.ibm.com>
2026-08-03 16:51:34 +02:00
Claudio Imbrenda
e4d678900a KVM: s390: Free the mmu cache when kvm_arch_vcpu_create() fails
The mmu cache is the first thing that is allocated in
kvm_arch_vcpu_create(), but in case of failure it was not freed.

Fix by freeing the mmu cache in case of failure.

Refactor kvm_arch_vcpu_create() to use scope-based cleanup instead of
gotos.

Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-11-imbrenda@linux.ibm.com>
2026-08-03 16:51:34 +02:00
Claudio Imbrenda
dab62d2187 KVM: s390: ucontrol: Add missing locking around gmap_remove_child()
gmap_remove_child() needs to be called while holding the children_lock
of the parent gmap. This was not the case in the error handling path of
kvm_arch_vcpu_create() for UCONTROL guests.

Fix by adding the missing lock.

Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-10-imbrenda@linux.ibm.com>
2026-08-03 16:51:34 +02:00
Claudio Imbrenda
ec21534627 KVM: s390: cmma: Fix dirty tracking when removing memslot
When a memslot is removed, all ptes that mapped the slot are cleared or
even deallocated. If this happens while the system is in migration
mode, and if cmma-dirty pages are removed, the cmma-dirty counter will
not reflect reality.

Fix by appropriately decrementing the cmma-dirty counter when removing
a memslot.

Opportunistically improve kvm_arch_commit_memory_region() to use
__free() for the struct kvm_s390_mmu_cache.

Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-9-imbrenda@linux.ibm.com>
2026-08-03 16:51:34 +02:00
Claudio Imbrenda
4db7207052 KVM: s390: Fix race in __do_essa()
An unlikely race between __do_essa() and kvm_s390_vm_start_migration(),
kvm_s390_vm_stop_migration(), or dat_get_cmma() was possible.

Fix by locking kvm->slots_arch_lock. Since this is not a hot path, the
overhead of an additional mutex is negligible.

Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-8-imbrenda@linux.ibm.com>
2026-08-03 16:51:34 +02:00
Claudio Imbrenda
d699986f11 KVM: s390: Fix leaking of PGM_ADDRESSING to userspace
If kvm_s390_set_cmma_bits() is asked to set CMMA values outside of a
memslot, PGM_ADDRESSING (5) is returned, instead of a negative error
value.

Same issue with kvm_s390_{g,s}et_skeys(), kvm_s390_keyop(), and
dat_reset_reference_bit().

Fix by returning -EFAULT whenever the return value would be > 0, which
is consistent with the behaviour before the gmap rewrite.

Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-7-imbrenda@linux.ibm.com>
2026-08-03 16:51:33 +02:00
Claudio Imbrenda
d301ade418 KVM: s390: ucontrol: Fix sca_clear_ext_call()
When cleaning up a UCONTROL VM, sca_clear_ext_call() will touch memory
outside of the allocated ESCA block, and UCONTROL VMs don't even use
ESCA.

Fix by not touching ESCA for UCONTROL VMs, and fence the
KVM_S390_INTERRUPT ioctl altogether. Add extra checks in
sca_ext_call_pending() and sca_inject_ext_call() to make sure UCONTROL
VMs won't touch ESCA.

Fencing does not cause regressions with userspace, since UCONTROL VMs
never used KVM_S390_INTERRUPT ioctls.

Fixes: 7d43bafcff ("KVM: s390: Make provisions for ESCA utilization")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-6-imbrenda@linux.ibm.com>
2026-08-03 16:51:33 +02:00
Claudio Imbrenda
a0496b40a4 KVM: s390: Fix overclearing ESCA in case of error
If an attempt is made to create a vCPU with an already existing ID,
the duplicated vCPU will be destroyed. When destroying a vCPU, its
ESCA entry will be cleared. In the above scenario, the spurious
duplicate vCPU is destroyed, but the ESCA entry corresponding to the
original vCPU is cleared.

Fix by skipping clearing the ESCA entry if the vCPU creation was not
successful, i.e. if the vcpu->arch.initialized is still zero.

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Fixes: abf4a71ed9 ("KVM: s390: Unlink vcpu on destroy - v2")
[ Added Fixes tag while picking -- Claudio ]
Message-ID: <20260803124040.126471-5-imbrenda@linux.ibm.com>
2026-08-03 16:51:33 +02:00
Claudio Imbrenda
b050f741fd KVM: s390: Fix kvm_s390_vcpu_unsetup_cmma()
In some cases kvm_s390_vcpu_unsetup_cmma() can be called with a 0
cbrlo; in such cases, if running with V != R, free_page() will attempt
to free physical page 0.

Fix by freeing cbrlo only if it's non-zero.

Fixes: b31605c12f ("KVM: s390: make cmma usage conditionally")
Fixes: 29b40f105e ("KVM: s390: protvirt: Add initial vm and cpu lifecycle handling")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-4-imbrenda@linux.ibm.com>
2026-08-03 16:51:33 +02:00
Claudio Imbrenda
f8e370058e KVM: s390: Do not free SCA if it was not allocated
If VM creation fails early in kvm_arch_init_vm(), the cleanup code
tries to free up the SCA, even though the address is 0. Due to using
free_pages_exact(), only the first page is skipped, accidentally
freeing pages 1, 2, and 3.

Fix by checking whether the pointer is NULL before attempting to free
the SCA in sca_dispose().

Fixes: e72753ed12 ("KVM: s390: Use ESCA instead of BSCA at VM init")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-3-imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
2026-08-03 16:51:28 +02:00
Claudio Imbrenda
496e0f706b KVM: s390: Fix unlikely NULL gmap dereference
When creating a new vCPU, kvm_vm_ioctl_create_vcpu() will call
kvm_arch_vcpu_postcreate() after the file descriptor for the new vCPU
has been created. The new file descriptor has not been returned yet,
but a malicious userspace program could try to guess it.

If a malicious userspace program manages to start the newly created vCPU
before kvm_arch_vcpu_postcreate() is called, __vcpu_run() will try to
dereference vcpu->arch.gmap and trigger a NULL pointer dereference.

Fix this by adding a new field to struct kvm_vcpu_arch to keep track of
the initialization status of the vCPU. Refuse to run a vCPU that is not
fully initialized.

Fixes: dafd032a15 ("KVM: s390: move vcpu specific initalization to a later point")
Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-2-imbrenda@linux.ibm.com>
2026-08-03 15:39:05 +02:00
Linus Torvalds
0e672789d4 s390 updates for 7.2-rc6
- Fix PCI MMIO write syscall falsely reporting success for mappings not
   valid for MMIO when MIO is unavailable by returning -EFAULT
 
 - Fix CPRB parameter buffer overflows in zcrypt CCA AES cipher and ECC
   private key conversion by rejecting oversized key tokens
 
 - Fix buffer overreads and length underflow in pkey and zcrypt CCA token
   validation by checking length fields against actual buffer sizes
 
 - Fix out of bounds permission bitmap access in zcrypt EP11 admin CPRB
   filtering on custom device nodes by using AP_DOMAINS as the limit
 
 - Fix speculative permission bitmap reads in zcrypt CCA and EP11 admin
   CPRB handling by sanitizing user controlled domain indexes
 
 - Fix sensitive key material left in zcrypt CCA clear key import buffers
   by scrubbing CPRB and temporary buffers after use
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Merge tag 's390-7.2-6' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 updates from Vasily Gorbik:

 - Fix PCI MMIO write syscall falsely reporting success for mappings not
   valid for MMIO when MIO is unavailable by returning -EFAULT

 - Fix CPRB parameter buffer overflows in zcrypt CCA AES cipher and ECC
   private key conversion by rejecting oversized key tokens

 - Fix buffer overreads and length underflow in pkey and zcrypt CCA
   token validation by checking length fields against actual buffer
   sizes

 - Fix out of bounds permission bitmap access in zcrypt EP11 admin CPRB
   filtering on custom device nodes by using AP_DOMAINS as the limit

 - Fix speculative permission bitmap reads in zcrypt CCA and EP11 admin
   CPRB handling by sanitizing user controlled domain indexes

 - Fix sensitive key material left in zcrypt CCA clear key import
   buffers by scrubbing CPRB and temporary buffers after use

* tag 's390-7.2-6' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/zcrypt: Fix missing mem scrub at clear key import in cca_clr2cipherkey()
  s390/zcrypt: Close speculative mem read possibility
  s390/zcrypt: Fix wrong domain value verification with EP11 CPRBs
  s390/zcrypt: Fix buffer over-read in cca_cipher2protkey
  s390/zcrypt: Validate length for CCA ECC private key requests
  s390/zcrypt: Validate length for CCA AES cipher key requests
  s390/pci: Fix s390_pci_mmio_write syscall error return without MIO
2026-08-02 11:55:49 -07:00
Niklas Schnelle
b7ab86bdc6 s390/pci: Fix s390_pci_mmio_write syscall error return without MIO
On a machine without PCI memory-I/O (MIO) support or when running with
pci=nomio the s390 specific PCI MMIO write syscall checks if the MMIO
cookie is above ZPCI_IOMAP_ADDR_BASE as a sanity check before even
trying to perform the MMIO. If this check fails the return value was
left unchanged and thus 0 from prior operations falsely indicating
success. This could potentially confuse user-space into falsely
believing the MMIO, on a mapping not valid for MMIO was successful.

Fix this by setting the return value to -EFAULT prior to the check
following the same pattern as elsewhere in the same function.

Cc: stable@vger.kernel.org
Reviewed-by: Julian Ruess <julianr@linux.ibm.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Fixes: a67a88b0b8 ("s390/pci: remove races against pte updates")
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2026-07-31 13:31:19 +02:00
Paolo Bonzini
70f526a0f9 KVM: s390: Fixes for 7.2
- several fixes for PCI passthru in s390 kvm
 - fix a 7.2-rc regression in the adapter interrupt mapping code
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Merge tag 'kvm-s390-master-7.2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: Fixes for 7.2

- several fixes for PCI passthru in s390 kvm
- fix a 7.2-rc regression in the adapter interrupt mapping code
2026-07-28 17:43:18 +02:00
Jaehoon Kim
9972befc3e KVM: s390: Fall back to short-term pinning in MAP ioctl
FOLL_LONGTERM pinning fails for some memory types, such as file-backed
guest memory. As a result, kvm_s390_adapter_map() returns -EINVAL and
irqfd adapter registration fails even though interrupt delivery could
still work via the existing non-atomic path.

When FOLL_LONGTERM pinning fails, verify that the page is accessible
using a short-term pin instead. If the short-term pin succeeds, unpin
the page and add a map entry with pinned=false to preserve MAP/UNMAP
symmetry. The non-atomic irqfd path already performs short-term pinning
for interrupt delivery, so this restores the previous behavior for
memory that cannot be pinned long-term.

get_map_info() is updated to return NULL for unpinned entries so that
the atomic irqfd fast path falls back to the non-atomic path.
kvm_s390_adapter_unmap() and kvm_s390_unmap_all_adapters() skip dirty
marking and unpin for unpinned entries.

Update Documentation/virt/kvm/devices/s390_flic.rst to reflect the
new MAP/UNMAP behavior.

Fixes: c9a5688380 ("KVM: s390: Add map/unmap ioctl and clean mappings post-guest")
Signed-off-by: Jaehoon Kim <jhkim@linux.ibm.com>
Reviewed-by: Douglas Freimuth <freimuth@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-27 09:23:53 +02:00
Farhan Ali
868d32ac72 KVM: s390: pci: Validate AIBV and AISB before pinning guest pages
The AIBV holds one bit per MSI-X vector for a given function. The size of
the bit vector is derived from the NOI and the AIBVO. If the size of the
AIBV exceeds a single page boundary, then reject the request as we cannot
safely pin the guest AIBV.

Similarly reject the request if the AISB address is not 8-byte aligned as
the architecture requires doubleword alignment for the summary bit address.
Since the AISBO can address up to 64 bits, the size of the AISB can only be
8 bytes for the function. This also ensures the AISB doesn't exceed a
single page boundary.

Fixes: 3c5a1b6f0a ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
Cc: stable@vger.kernel.org
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-24 11:26:54 +02:00
Farhan Ali
5580c9858f KVM: s390: pci: Fix resource leak on IRQ registration failure
Currently if kvm_zpci_set_airq() fails, kvm_s390_pci_aif_enable() returns
the error code but doesn't do any resource cleanup thus leaking resources.
Fix this by cleaning up all the resources such as the GAITE, AIBV, AISB and
unpinning any pinned pages. While at it, remove dead code that stored FIB
values that were never referenced.

As part of the cleanup, we are also holding the aift_lock a bit longer, as
we hold the lock while executing the MPCIFC instruction. Though this is not
strictly necessary, it means we don't have to drop and re-acquire in the
error case.

Fixes: 3c5a1b6f0a ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
Cc: stable@vger.kernel.org
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-24 11:26:54 +02:00
Farhan Ali
8bf09b9b7d KVM: s390: pci: Fix NULL dereference on AIBV allocation failure
The airq_iv_create() can return NULL on failure, but the return value was
never checked. If it fails, zdev->aibv will be NULL and fail when
dereferenced in kvm_zpci_set_airq(). Add a NULL check and free the
previously allocated AISB bit and zdev->aisb on failure.

Fixes: 3c5a1b6f0a ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
Cc: stable@vger.kernel.org
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-24 11:26:54 +02:00
Farhan Ali
f86842e4d6 KVM: s390: pci: Fix missing error codes and memory unaccounting
In kvm_s390_pci_aif_enable() two error paths failed to set an error code,
causing the function to return 0 on failure. It also failed to rollback
memory accounting on failure. Fix both by propagating an error code on
failure and calling unaccount_mem() in the cleanup path.

Fixes: 3c5a1b6f0a ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
Cc: stable@vger.kernel.org
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-24 11:26:53 +02:00
Farhan Ali
36f6999ecd KVM: s390: pci: Fix memory accounting for pinned/unpinned pages
The account_mem() and unaccount_mem() functions call get_uid() which
increments the reference count of struct user_struct on every invocation.
But we don't decrement the count by calling free_uid(). It also
accounted/unaccounted the pages against the current->mm. But its possible
the unaccount_mem() can be called from a different process context than the
one that originally pinned the pages.

Let's fix this by storing the pinning process user_struct and mm_struct
when accounting for pinned pages, and subsequently free these resources
when the pages are unpinned.

Fixes: 3c5a1b6f0a ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
Cc: stable@vger.kernel.org
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
[borntraeger@linux.ibm.com: Fixed whitespace]
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-24 11:26:53 +02:00
Farhan Ali
8fa01be5a6 KVM: s390: pci: Reject adapter interrupt forwarding if already enabled
The MPCIFC instruction doesn't allow registering adapter interrupts without
first unregistering. So reject any request to enable interrupt forwarding
if its already enabled for the zPCI device. This also fixes overwriting and
thus leaking resources when the ioctl is called multiple times for the same
device.

Fixes: 3c5a1b6f0a ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
Cc: stable@vger.kernel.org
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-24 11:26:53 +02:00
Linus Torvalds
d326f83e81 Lots of fixes, double the count even for the "new normal".
Largely due to my time off followed by a networking conference
 which distracted most maintainers (less so the AI generators).
 
 Including fixes from Bluetooth and WiFi.
 
 Current release - regressions:
 
  - wifi: mt76: fix MAC address for non OF pcie cards
 
 Current release - new code bugs:
 
  - mptcp: fix BUILD_BUG_ON on legacy ARM config
 
  - wifi: cfg80211: guard optional PMSR nominal time
 
 Previous releases - regressions:
 
  - qrtr: ns: raise node count limit to 512, we arbitrarily picked
    256 as a limit, turns out it was too low for real world deployments
 
  - vhost-net: fix TX stall when vhost owns virtio-net header
 
  - eth: amd-xgbe: fix MAC_AUTO_SW handling in CL37 AN
 
  - wifi: ath12k: fix low MLO RX throughput on WCN7850
 
 Previous releases - always broken:
 
  - number of random AI fixes for SCTP, RDS and TIPC protocols
 
  - more AI-looking fixes for WiFi drivers
 
  - number of fixes for missing pointer reloading after skb pull
 
  - reject BPF redirect use from qdisc qevent block
 
  - tcp: initialize standalone TCP-AO response padding
 
  - vsock/virtio: collapse receive queue under memory pressure to avoid
    client OOMing the host with tiny messages
 
  - ipv4: icmp: fill flow parameters in icmp_route_lookup decoy lookup,
    make sure the ICMP response routing follows the routing policy
 
  - gro: fix double aggregation of flush-marked skbs
 
  - ovpn: fix various refcount bugs
 
  - tls: device: push pending open record on splice EOF
 
  - eth: mlx5:
   - use sender devcom for MPV master-up
   - fix MCIA register buffer overflow on 32 dword reads
 
 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Pull networking fixes from Jakub Kicinski:
 "Lots of fixes, double the count even for the 'new normal'. Largely due
  to my time off followed by a networking conference which distracted
  most maintainers (less so the AI generators).

  Including fixes from Bluetooth and WiFi.

  Current release - regressions:

   - wifi: mt76: fix MAC address for non OF pcie cards

  Current release - new code bugs:

   - mptcp: fix BUILD_BUG_ON on legacy ARM config

   - wifi: cfg80211: guard optional PMSR nominal time

  Previous releases - regressions:

   - qrtr: ns: raise node count limit to 512, we arbitrarily picked
     256 as a limit, turns out it was too low for real world deployments

   - vhost-net: fix TX stall when vhost owns virtio-net header

   - eth: amd-xgbe: fix MAC_AUTO_SW handling in CL37 AN

   - wifi: ath12k: fix low MLO RX throughput on WCN7850

  Previous releases - always broken:

   - number of random AI fixes for SCTP, RDS and TIPC protocols

   - more AI-looking fixes for WiFi drivers

   - number of fixes for missing pointer reloading after skb pull

   - reject BPF redirect use from qdisc qevent block

   - tcp: initialize standalone TCP-AO response padding

   - vsock/virtio: collapse receive queue under memory pressure to avoid
     client OOMing the host with tiny messages

   - ipv4: icmp: fill flow parameters in icmp_route_lookup decoy lookup,
     make sure the ICMP response routing follows the routing policy

   - gro: fix double aggregation of flush-marked skbs

   - ovpn: fix various refcount bugs

   - tls: device: push pending open record on splice EOF

   - eth: mlx5:
      - use sender devcom for MPV master-up
      - fix MCIA register buffer overflow on 32 dword reads"

* tag 'net-7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (234 commits)
  drop_monitor: perform u64_stats updates under IRQ-disabled section
  drop_monitor: fix size calculations for 64-bit attributes
  net: drop_monitor: fix info leak in NET_DM_ATTR_PAYLOAD
  mptcp: fix BUILD_BUG_ON on legacy ARM config
  selftests: mptcp: userspace_pm: fix undefined variable port
  mptcp: fix stale skb->sk reference on subflow close
  mptcp: pm: userspace: fix use-after-free in get_local_id
  mptcp: decrement subflows counter on failed passive join
  mac802154: hold an interface reference across the scan worker
  sctp: don't free the ASCONF's own transport in DEL-IP processing
  phonet: check register_netdevice_notifier() error in phonet_device_init()
  phonet: pep: fix use-after-free in pep_get_sb()
  bnge/bng_re: fix ring ID widths
  tipc: fix integer overflow in tipc_recvmsg() and tipc_recvstream()
  net: airoha: fix ETS channel derivation in airoha_tc_setup_qdisc_ets()
  mctp: check register_netdevice_notifier() error in mctp_device_init()
  ptp: netc: explicitly clear TMR_OFF during initialization
  rds: tcp: unregister sysctl before tearing down listen socket
  ipv6: Change allocation flags to match rcu_read_lock section requirements
  net: slip: serialize receive against buffer reallocation
  ...
2026-07-23 12:58:08 -07:00
Sven Schnelle
9de445d829 s390/ptff: Export ptff_function_mask[]
Export the ptff_function_mask to make ptff_query() usable in modules.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://patch.msgid.link/20260714130342.1971700-2-svens@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-23 07:02:34 -07:00
Linus Torvalds
c6859eed75 s390 updates for 7.2-rc4
- Fix checksum lib on machines without the vector facility where the
   non-vector fallback made csum_partial() calculate the checksum from
   address 0 instead of the provided buffer
 
 - Fix cpum_cf perf event initialization missing speculation barrier for
   user controlled event numbers used as generic event array indexes
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Merge tag 's390-7.2-5' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 fixes from Vasily Gorbik:

 - Fix checksum lib on machines without the vector facility where the
   non-vector fallback made csum_partial() calculate the checksum from
   address 0 instead of the provided buffer

 - Fix cpum_cf perf event initialization missing speculation barrier for
   user controlled event numbers used as generic event array indexes

* tag 's390-7.2-5' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/perf_cpum_cf: Add missing array_index_nospec() to __hw_perf_event_init()
  s390/checksum: Fix csum_partial() without vector facility
2026-07-18 16:48:44 -07:00
Sumanth Korikkar
49145bce53 s390/perf_cpum_cf: Add missing array_index_nospec() to __hw_perf_event_init()
ev variable is userspace controlled via event->attr.config and used
as an array index after bounds checking, but without speculation
barriers.

Add the missing array_index_nospec() call to prevent speculative
execution.

Cc: stable@vger.kernel.org
Fixes: 212188a596 ("[S390] perf: add support for s390x CPU counters")
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2026-07-15 17:35:42 +02:00
Vasily Gorbik
4bb06b60d9 s390/checksum: Fix csum_partial() without vector facility
Currently csum_partial() calls csum_copy() with copy=false and dst=NULL.
On machines without the vector facility, csum_copy() falls back to
cksm(dst, ...), causing the checksum to be calculated from address zero
instead of the source buffer.

The VX implementation already checksums data loaded from src. Make the
fallback do the same by passing src to cksm().

Fixes: dcd3e1de9d ("s390/checksum: provide csum_partial_copy_nocheck()")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2026-07-15 17:35:42 +02:00
Paolo Bonzini
5246d32d4b KVM: s390: Fixes for 7.2
- more gmap KVM memory management fixes
 - PCI passthru fixes
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Merge tag 'kvm-s390-master-7.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: Fixes for 7.2

- more gmap KVM memory management fixes
- PCI passthru fixes
2026-07-15 12:15:40 +02:00
Matthew Rosato
3e3aa6da87 KVM: s390: pci: Fix handling of AIF enable without AISB
When a guest seeks to register IRQs without a summary bit specified,
ensure that the associated GAITE then stores 0 for the guest AISB
location instead of virt_to_phys(page_address(NULL)).

Fixes: 3c5a1b6f0a ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
Cc: stable@vger.kernel.org
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-09 16:23:10 +02:00
Claudio Imbrenda
9489220fe0 KVM: s390: Improve kvm_s390_vm_stop_migration()
There is no need to clear cmma-dirty state if the VM is not using CMMA.

Skip the CMMA-related code if CMMA is not in use.

Fixes: 6cfd47f91f ("KVM: s390: Fix cmma dirty tracking")
Fixes: 190df4a212 ("KVM: s390: CMMA tracking, ESSA emulation, migration mode")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-09 10:26:10 +02:00
Claudio Imbrenda
4d4a21e38f KVM: s390: Fix dat_crste_walk_range() early return
If a walk entry handler for a lower level returns a value,
dat_crste_walk_range() will not return immediately, but instead loop
again and move to the next entry.

This means that some entries are potentially skipped, and early return
is ignored. Skipped entries might lead to all kinds of issues, given
that the caller expects them to not be skipped. Early return is often
used to interrupt a walk when a rescheduling is needed; if it is
ignored it can lead to stalls.

Fix by breaking from the loop immediately if the walk to a lower level
returned non-zero.

Fixes: 2db149a0a6 ("KVM: s390: KVM page table management functions: walks")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-09 10:26:10 +02:00
Claudio Imbrenda
866d03de6d KVM: s390: vsie: Avoid potential deadlock with real spaces
The natural lock ordering is mmu_lock -> children_lock, but in
gmap_create_shadow() the reverse order is used when handling shadowing
of real address spaces.

Convert the inner locking of kvm->mmu_lock to a trylock; return -EAGAIN
if the lock is busy, and let the caller try again.

This path is not expected to happen in real-life scenarios, so its
performance is not important.

Fixes: a2c17f9270 ("KVM: s390: New gmap code")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-09 10:26:10 +02:00
Haoxiang Li
7b69729046 KVM: s390: pci: Fix GISC refcount leak on AIF enable failure
kvm_s390_gisc_register() registers the guest ISC before pinning
the guest interrupt forwarding pages and allocating the AISB bit.
If any of the later setup steps fails, the function unwinds the
pinned pages and other local state, but does not unregister the
GISC reference. Add the missing kvm_s390_gisc_unregister() to the
error unwind path.

Fixes: 3c5a1b6f0a ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260624061910.2794734-1-haoxiang_li2024@163.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2026-07-09 10:25:56 +02:00
Bastian Blank
7d5c2f6791 s390: Add build salt to the vDSO
The vDSO needs to have a unique build id in a similar manner
to the kernel and modules. Use the build salt macro.

Signed-off-by: Bastian Blank <waldi@debian.org>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2026-07-08 17:02:48 +02:00
Gerald Schaefer
ec84aad4c3 s390/mm: Fix type mismatch in get_align_mask().
Commit 86f48f922b ("s390/mmap: disable mmap alignment when
randomize_va_space = 0") introduced get_align_mask() with return type of
'int', while the target field 'info.align_mask' in struct
vm_unmapped_area_info is 'unsigned long'.

With currently used masks, this should not cause truncation issues, but
fix it and return 'unsigned long' to avoid future problems.

Fixes: 86f48f922b ("s390/mmap: disable mmap alignment when randomize_va_space = 0")
Cc: stable@vger.kernel.org # v6.9+
Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2026-07-08 17:02:47 +02:00
Heiko Carstens
b7577fe4c4 s390/diag: Add missing array_index_nospec() call to memtop_get_page_count()
'level' is user space controlled and used to read from an array. Add the
missing array_index_nospec() call to prevent speculative execution.

Cc: stable@vger.kernel.org
Fixes: 0d30871739 ("s390/diag: Add memory topology information via diag310")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Mete Durlu <meted@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2026-07-08 17:02:47 +02:00
Uwe Kleine-König (The Capable Hub)
ecca1d63c1 Replace <linux/mod_devicetable.h> by more specific <linux/device-id/*.h> (headers)
<linux/mod_devicetable.h> is included in a many files:

	$ git grep '<linux/mod_devicetable.h>' ef0c9f75a1 | wc -l
	1598

; some of them are widely used headers. To stop mixing up different and
unrelated driver( type)s let the subsystem headers only use the subset
of the recently split <linux/mod_devicetable.h> that are relevant for
them.

The fallout (I hope) is addressed in the previous commits that handle
sources relying on e.g. <linux/i2c.h> pulling in the full legacy header
and thus providing pci_device_id.

Acked-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://patch.msgid.link/199fe46b624ba07fb9bd3e0cd6ff13757932cb5f.1782808461.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König (The Capable Hub) <u.kleine-koenig@baylibre.com>
2026-07-03 07:38:16 +02:00
Linus Torvalds
c75597caad s390:
* Fix S390_USER_OPEREXEC so it can now be enabled regardless of other
   unrelated capabilities
 
 * Fix handling of the _PAGE_UNUSED pte bit that could lead to guest
   memory corruption in some scenarios
 
 * A bunch of misc gmap fixes (locking, behaviour under memory pressure)
 
 * Fix CMMA dirty tracking
 
 x86:
 
 * Tidy up some WARN_ON() and BUG_ON(), replacing them with WARN_ON_ONCE()
   or KVM_BUG_ON().  All of these have obviously never triggered, or
   somebody would have been annoyed earlier, but still.
 
 * Fix missing interrupt due to stale CR8 intercept
 
 * Add a statistic that can come in handy to debug leaks as well as the
   vulnerability to a class of recently-discovered issues.
 
 * Do not ask arch/x86/kernel to export default_cpu_present_to_apicid()
   just for KVM.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "s390:

   - Fix S390_USER_OPEREXEC so it can now be enabled regardless of other
     unrelated capabilities

   - Fix handling of the _PAGE_UNUSED pte bit that could lead to guest
     memory corruption in some scenarios

   - A bunch of misc gmap fixes (locking, behaviour under memory
     pressure)

   - Fix CMMA dirty tracking

  x86:

   - Tidy up some WARN_ON() and BUG_ON(), replacing them with
     WARN_ON_ONCE() or KVM_BUG_ON(). All of these have obviously never
     triggered, or somebody would have been annoyed earlier, but still...

   - Fix missing interrupt due to stale CR8 intercept

   - Add a statistic that can come in handy to debug leaks as well as
     the vulnerability to a class of recently-discovered issues

   - Do not ask arch/x86/kernel to export
     default_cpu_present_to_apicid() just for KVM"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (22 commits)
  x86/apic: KVM: Use cpu_physical_id() to get APIC ID of running vCPU for AVIC
  KVM: x86/mmu: Expose number of shadow MMU shadow pages as a stat
  KVM: x86: Unconditionally recompute CR8 intercept on PPR update
  KVM: VMX: Grab vmcs12 on CR8 interception update iff vCPU is in guest mode
  KVM: x86: WARN (once) if RTC pending EOI tracking goes off the rails
  KVM: x86: WARN and fail kvm_set_irq() if a PIC or I/O APIC vector is invalid
  KVM: x86: Bug the VM, not the kernel, if the ISR count {under,over}flows
  KVM: x86/mmu: Bug the VM, not the host kernel, if KVM write-protects upper SPTEs
  KVM: x86: Replace BUG_ON() with WARN_ON_ONCE() on "bad" nested GPA translation
  KVM: Replace guest-triggerable BUG_ON() in ioeventfd datamatch with get_unaligned()
  KVM: s390: Return failure in case of failure in kvm_s390_set_cmma_bits()
  KVM: s390: selftests: Fix cmma selftest
  KVM: s390: Fix cmma dirty tracking
  KVM: s390: Fix locking in kvm_s390_set_mem_control()
  KVM: s390: Fix handle_{sske,pfmf} under memory pressure
  KVM: s390: Fix code typo in gmap_protect_asce_top_level()
  KVM: s390: Do not set special large pages dirty
  KVM: s390: Fix dat_peek_cmma() overflow
  s390/mm: Fix handling of _PAGE_UNUSED pte bit
  KVM: s390: Fix typo in UCONTROL documentation
  ...
2026-06-25 10:21:13 -07:00
Paolo Bonzini
91b16b53a0 KVM: s390: Fix S390_USER_OPEREXEC and more gmap fixes
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Merge tag 'kvm-s390-next-7.2-2' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

* Fix S390_USER_OPEREXEC so it can now be enabled regardless of other
  unrelated capabilities

* Fix handling of the _PAGE_UNUSED pte bit that could lead to guest
  memory corruption in some scenarios

* A bunch of misc gmap fixes (locking, behaviour under memory pressure)

* Fix CMMA dirty tracking
2026-06-24 13:41:41 +02:00
Claudio Imbrenda
babe08404e KVM: s390: Return failure in case of failure in kvm_s390_set_cmma_bits()
If the allocation of the bits array failed, kvm_s390_set_cmma_bits()
would return 0 instead of an error code.

Rework the function to use the __free() macros and thus simplify the
code flow; when the above mentioned allocation fails, simply return
-ENOMEM.

Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260623153331.233784-10-imbrenda@linux.ibm.com>
2026-06-24 10:08:57 +02:00
Claudio Imbrenda
6cfd47f91f KVM: s390: Fix cmma dirty tracking
It is possible that some guest memory areas have not been touched yet
when starting migration mode, and thus have no ptes allocated. Only
existing and allocated ptes should count toward the total of dirty cmma
entries.

When starting migration mode, enable the migration_mode flag
immediately, so that any subsequent ESSA will trap in the host and
cause cmma_dirty_pages to be increased as needed.
Subsequently, set the cmma_d bit on all existing cmma-clean PGSTEs,
increasing cmma_dirty_pages as needed. Skipping cmma-dirty pages
prevents double counting.

Conversely, when disabling migration mode, set cmma_dirty_pages to 0
and clear the cmma_d bit in all existing PGSTEs.

The invariant is that when migration mode is off, no PGSTE has its
cmma_d bit set, and cmma_dirty_pages is 0. kvm->slots_lock protects
kvm_s390_vm_start_migration() and kvm_s390_vm_stop_migration() from
each other and from kvm_s390_get_cmma_bits().

Also fix dat_get_cmma() to properly wrap around if the first attempt
reached the end of guest memory without finding cmma-dirty pages.

[ imbrenda: Moved kvm_s390_sync_request_broadcast() before gmap_set_cmma_all_dirty() ]

Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260623153331.233784-8-imbrenda@linux.ibm.com>
2026-06-24 10:08:57 +02:00
Claudio Imbrenda
9b0bf9b93c KVM: s390: Fix locking in kvm_s390_set_mem_control()
Add the missing locking around dat_reset_cmma().

Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260623153331.233784-7-imbrenda@linux.ibm.com>
2026-06-24 10:08:57 +02:00
Claudio Imbrenda
2bd74dce08 KVM: s390: Fix handle_{sske,pfmf} under memory pressure
Under heavy memory pressure, handle_sske() and handle_pfmf() might
cause an endless loop if the mmu cache runs empty, the atomic
allocations fail, and the top-up function also fails. While quite
unlikely, that scenario is not impossible.

Fix the issue by not ignoring the return value of
kvm_s390_mmu_cache_topup(), and appropriately returning an error code
in case of failure.

Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260623153331.233784-6-imbrenda@linux.ibm.com>
2026-06-24 10:08:57 +02:00
Claudio Imbrenda
6e976afdfe KVM: s390: Fix code typo in gmap_protect_asce_top_level()
The correct length to pass to kvm_s390_get_guest_pages() is asce.tl + 1,
not asce.dt + 1. It was a typo, which, due to fortuitous circumstances,
did not cause bugs. It should nonetheless be fixed.

Fixes: e5f98a6899 ("KVM: s390: Add some helper functions needed for vSIE")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260623153331.233784-5-imbrenda@linux.ibm.com>
2026-06-24 10:08:56 +02:00
Claudio Imbrenda
e6c9b322c8 KVM: s390: Do not set special large pages dirty
Special pages / folios should not be set dirty. This also applies to
large pages.

Add a missing check in gmap_clear_young_crste() to prevent setting the
large page dirty if it is a special page.

Fixes: a2c17f9270 ("KVM: s390: New gmap code")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260623153331.233784-4-imbrenda@linux.ibm.com>
2026-06-24 10:08:56 +02:00
Claudio Imbrenda
7a386efcb2 KVM: s390: Fix dat_peek_cmma() overflow
If userspace passes a start address that is out of bounds,
_dat_walk_gfn_range() will fail with -EFAULT, but state.end will not be
touched and will stay 0. This will cause *count to underflow and report
a very high number, and the function will end up erroneously reporting
success.

Fix by only setting *count if the end address is not smaller than the
starting address. This way invalid starting addresses will correctly
return -EFAULT and *count will correctly indicate that no values have
been returned.

Fixes: 7b368470e1 ("KVM: s390: KVM page table management functions: CMMA")
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260623153331.233784-3-imbrenda@linux.ibm.com>
2026-06-24 10:08:56 +02:00
Claudio Imbrenda
d4bb00704a s390/mm: Fix handling of _PAGE_UNUSED pte bit
The _PAGE_UNUSED softbit should not really be lying around. Its sole
purpose is to signal to try_to_unmap_one() and try_to_migrate_one()
that the page can be discarded instead of being moved / swapped.

KVM has no way to know why a page is being unmapped, so it sets the bit
on userspace ptes corresponding to unused guest pages every time they
get unmapped. KVM has no reasonable way to clear the bit once the page
is in use again.

While set_ptes() checks and clears the bit, other paths that set new
ptes did not. This led to used pages being thrown out as if they were
unused, causing guest corruption.

Fix the issue by clearing the _PAGE_UNUSED bit for present ptes in
set_pte(), i.e. whenever a present pte is getting set. The check in
set_ptes() is then redundant and can be removed.

Also fix gmap_helper_try_set_pte_unused() to only set the bit if the
pte is present; the _PAGE_UNUSED bit is only defined for present ptes
and thus should not be set for non-present ptes.

Fixes: c98175b791 ("KVM: s390: Add gmap_helper_set_unused()")
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260623153331.233784-2-imbrenda@linux.ibm.com>
2026-06-24 10:08:56 +02:00
Eric Farman
02d61d3370 KVM: s390: Fix S390_USER_OPEREXEC enablement without STFLE 74
The KVM_CAP_S390_USER_OPEREXEC capability allows operation exceptions
to be forwarded to userspace. But the actual enablement at the hardware
level occurs in kvm_arch_vcpu_postcreate(), and only if STFLE.74 or
user_instr0 are enabled. The latter is associated with a separate
capability (KVM_CAP_S390_USER_INSTR0), so the only way this happens
for the USER_OPEREXEC capability is if STFLE.74 is enabled. KVM
unconditionally enables this bit in kvm_arch_init_vm(), but the guest
could disable it from the CPU model and thus ignore this capability.

Add USER_OPEREXEC to the check in kvm_arch_vcpu_postcreate(), such that
either capability would enable this type of exception.

Fixes: 8e8678e740 ("KVM: s390: Add capability that forwards operation exceptions")
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
[Fixed patch title, as recommended by frankja@linux.ibm.com]
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260507200836.3500368-2-farman@linux.ibm.com>
2026-06-24 10:01:56 +02:00