[GIT PULL] KVM fixes for Linux 7.2-rc6

[GIT PULL] KVM fixes for Linux 7.2-rc6

[Paolo Bonzini]

Linus,

The following changes since commit f5098b6bae761e346ebcd9da7f95622c04733cff:

  Linux 7.2-rc5 (2026-07-26 14:45:48 -0700)

are available in the Git repository at:

  https://git.kernel.org/pub/scm/virt/kvm/kvm.git tags/for-linus

for you to fetch changes up to 7d3aae206663c4e006b25a1c7a20a4029e67da76:

  KVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active (2026-07-29 23:39:36 +0200)

----------------------------------------------------------------
Arm:

- Fix a tiny buglet when propagating the deactivation of an interrupt
  from a nested guest, which happened to trigger a gold plated CPU bug
  on a particular implementation

- Fix a race between LPI unmapping and mapping, resulting in leaked
  LPIs

- Make LPI mapping more robust on memory allocation failure

- Fix the handling of the EL2 tracing clock being disabled

- A couple of Sashiko-driven fixes for corner cases in the EL2 tracing
  code

- Add missing sysreg tracepoint for the EL2 code

- Tidy-up the mutual exclusion of guest-memfd and MTE

- Update Fuad's email address to point to @linux.dev

s390:

- several fixes for PCI passthru in s390 kvm

- fix a 7.2-rc regression in the adapter interrupt mapping code

x86:

- Add memory clobber to asm for VMX instructions; without one, the compiler
  could reorder them in troublesome ways because "asm volatile" and "asm goto"
  only protect against removal of the asm.

- Cancel delayed I/O APIC EOI handling before destroying vCPUs

- Check all address spaces (normal and SMM) for write tracking and large
  pages, not just the current one.

- Always update x2APIC MSR intercepts for L1 when AVIC is deactivated,
  even if not running L1.  If the deactivation is VM-wide rather than being
  caused by something in L2's vCPU state, after a nested vmexit L1 will
  be able to access the host's APIC state.

----------------------------------------------------------------
Alexandru Elisei (1):
      KVM: arm64: Reject guest_memfd memslots when the VM has MTE

Carlos López (2):
      KVM: arm64: vgic: Fix race between LPI release and re-registration
      KVM: arm64: vgic: Mitigate potential LPI registration failure

D Scott Phillips (1):
      KVM: arm64: vgic: Avoid double-deactivate of IRQs in the nested context

Farhan Ali (6):
      KVM: s390: pci: Reject adapter interrupt forwarding if already enabled
      KVM: s390: pci: Fix memory accounting for pinned/unpinned pages
      KVM: s390: pci: Fix missing error codes and memory unaccounting
      KVM: s390: pci: Fix NULL dereference on AIBV allocation failure
      KVM: s390: pci: Fix resource leak on IRQ registration failure
      KVM: s390: pci: Validate AIBV and AISB before pinning guest pages

Fuad Tabba (1):
      KVM: arm64: Update Fuad Tabba's email address

Jaehoon Kim (1):
      KVM: s390: Fall back to short-term pinning in MAP ioctl

Jinu Kim (2):
      KVM: x86/mmu: Check write tracking in all address spaces
      KVM: x86/mmu: Check all address spaces before skipping unsync

Paolo Bonzini (3):
      Merge tag 'kvm-s390-master-7.2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD
      Merge tag 'kvmarm-fixes-7.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
      KVM: VMX: add memory clobber to asm for VMX instructions

Sean Christopherson (1):
      KVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active

Vincent Donnefort (4):
      KVM: arm64: Fix hyp_trace clock disabling
      KVM: arm64: Fix potential leak in hyp_trace_buffer_alloc_bpages_backing
      KVM: arm64: Fix hyp_trace_desc allocation size in hyp_trace_load()
      KVM: arm64: Add missing hyp_enter when trapping sysreg

Weiming Shi (1):
      KVM: x86: Cancel delayed I/O APIC EOI handling before destroying vCPUs

 .mailmap                                     |   1 +
 Documentation/arch/arm64/silicon-errata.rst  |   4 +
 Documentation/virt/kvm/api.rst               |   6 ++
 Documentation/virt/kvm/devices/s390_flic.rst |  15 +++-
 MAINTAINERS                                  |   2 +-
 arch/arm64/include/asm/kvm_hypevents.h       |   1 +
 arch/arm64/kvm/arm.c                         |  25 +++++--
 arch/arm64/kvm/hyp/nvhe/hyp-main.c           |   1 +
 arch/arm64/kvm/hyp_trace.c                   |  36 ++++++---
 arch/arm64/kvm/mmu.c                         |   4 +
 arch/arm64/kvm/vgic/vgic-its.c               |  25 +++++--
 arch/arm64/kvm/vgic/vgic-v3.c                |   8 +-
 arch/arm64/kvm/vgic/vgic.c                   |  18 ++---
 arch/s390/include/asm/kvm_host.h             |   5 ++
 arch/s390/kvm/interrupt.c                    |  56 ++++++++++----
 arch/s390/kvm/pci.c                          | 107 +++++++++++++++++++++------
 arch/s390/kvm/pci.h                          |   2 +
 arch/x86/kvm/mmu/mmu.c                       |  22 +++++-
 arch/x86/kvm/mmu/page_track.c                |  32 ++++++--
 arch/x86/kvm/svm/avic.c                      |   8 --
 arch/x86/kvm/vmx/vmx_ops.h                   |   8 +-
 arch/x86/kvm/x86.c                           |   6 ++
 include/kvm/arm_vgic.h                       |   3 -
 23 files changed, 298 insertions(+), 97 deletions(-)

Re: [GIT PULL] KVM fixes for Linux 7.2-rc6

[Linus Torvalds]

On Wed, 29 Jul 2026 at 14:45, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> - Add memory clobber to asm for VMX instructions; without one, the compiler
>   could reorder them in troublesome ways because "asm volatile" and "asm goto"
>   only protect against removal of the asm.

This is simply not true.

"asm volatile" is not just a "don't remove". It is an ordering
constraint too. It cannot move wrt other asm volatiles.

I've merged this, because that added clobber won't really hurt, but
the bug is simply not what the description says it is.

You have to have a memory clobber if you modify memory, or read memory
that you didn't tell about.

So asm volatile is very much a "you can't re-order this asm or move it
around significantly".

But at the same time it does *not* necessarily protect against the
compiler re-ordering *other* things - like regular non-volatile memory
reads and writes.

So I think the commit message is misleading and actively wrong, and is
stating things that simply aren't even remotely true.

In fact, I think the "none of this has been observed" probably means
that the code wasn't actually even buggy, and clearly the people
involved didn't really think things through.

If all accesses are to memory that gcc isn't aware of, and all of
those are done with 'asm volatile', then the code is fine *without* a
memory clobber. The asms won't be re-ordered wrt each other, because
you have told the compiler that there are side effects.

But if you do *regular* memory accesses to some memory area, and then
you use "asm volatile" without a memory clobber, then gcc may be
moving those regular memory accesses around the asm.

See the difference?

               Linus

Re: [GIT PULL] KVM fixes for Linux 7.2-rc6

[Paolo Bonzini]

On Thu, Jul 30, 2026 at 12:02 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Wed, 29 Jul 2026 at 14:45, Paolo Bonzini <pbonzini@redhat.com> wrote:
> >
> > - Add memory clobber to asm for VMX instructions; without one, the compiler
> >   could reorder them in troublesome ways because "asm volatile" and "asm goto"
> >   only protect against removal of the asm.
>
> This is simply not true.
>
> "asm volatile" is not just a "don't remove". It is an ordering
> constraint too. It cannot move wrt other asm volatiles.
> So asm volatile is very much a "you can't re-order this asm or move it
> around significantly". [...]
>
> But at the same time it does *not* necessarily protect against the
> compiler re-ordering *other* things - like regular non-volatile memory
> reads and writes.

Then I was mistaken that reordering of asms could still happen without
a memory clobber. I agree that the commit message overstates what the
compiler can decide to do.

Thanks for the explanation,

Paolo

Re: [GIT PULL] KVM fixes for Linux 7.2-rc6

[pr-tracker-bot]

The pull request you sent on Wed, 29 Jul 2026 23:44:59 +0200:

> https://git.kernel.org/pub/scm/virt/kvm/kvm.git tags/for-linus

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/fc46aed51f6280801f43a2cf4b5060cc33b572f9

Thank you!

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