[GIT PULL] KVM: x86: Fixes for 6.14-rcN

[GIT PULL] KVM: x86: Fixes for 6.14-rcN

[Sean Christopherson]

Please pull a handful of fixes for 6.14.  The DEBUGCTL changes are the most
urgent, as they fix a bug that was introduced in 6.13 that results in Steam
(and other applications) getting killed due to unexpected #DBs.

The following changes since commit c2fee09fc167c74a64adb08656cb993ea475197e:

  KVM: x86: Load DR6 with guest value only before entering .vcpu_run() loop (2025-02-12 08:59:38 -0800)

are available in the Git repository at:

  https://github.com/kvm-x86/linux.git tags/kvm-x86-fixes-6.14-rcN.2

for you to fetch changes up to f9dc8fb3afc968042bdaf4b6e445a9272071c9f3:

  KVM: x86: Explicitly zero EAX and EBX when PERFMON_V2 isn't supported by KVM (2025-03-04 09:19:18 -0800)

----------------------------------------------------------------
KVM x86 fixes for 6.14-rcN #2

 - Set RFLAGS.IF in C code on SVM to get VMRUN out of the STI shadow.

 - Ensure DEBUGCTL is context switched on AMD to avoid running the guest with
   the host's value, which can lead to unexpected bus lock #DBs.

 - Suppress DEBUGCTL.BTF on AMD (to match Intel), as KVM doesn't properly
   emulate BTF.  KVM's lack of context switching has meant BTF has always been
   broken to some extent.

 - Always save DR masks for SNP vCPUs if DebugSwap is *supported*, as the guest
   can enable DebugSwap without KVM's knowledge.

 - Fix a bug in mmu_stress_tests where a vCPU could finish the "writes to RO
   memory" phase without actually generating a write-protection fault.

 - Fix a printf() goof in the SEV smoke test that causes build failures with
   -Werror.

 - Explicitly zero EAX and EBX in CPUID.0x8000_0022 output when PERFMON_V2
   isn't supported by KVM.

----------------------------------------------------------------
Sean Christopherson (11):
      KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the STI shadow
      KVM: selftests: Assert that STI blocking isn't set after event injection
      KVM: SVM: Drop DEBUGCTL[5:2] from guest's effective value
      KVM: SVM: Suppress DEBUGCTL.BTF on AMD
      KVM: x86: Snapshot the host's DEBUGCTL in common x86
      KVM: SVM: Manually context switch DEBUGCTL if LBR virtualization is disabled
      KVM: x86: Snapshot the host's DEBUGCTL after disabling IRQs
      KVM: SVM: Save host DR masks on CPUs with DebugSwap
      KVM: SVM: Don't rely on DebugSwap to restore host DR0..DR3
      KVM: selftests: Ensure all vCPUs hit -EFAULT during initial RO stage
      KVM: selftests: Fix printf() format goof in SEV smoke test

Xiaoyao Li (1):
      KVM: x86: Explicitly zero EAX and EBX when PERFMON_V2 isn't supported by KVM

 arch/x86/include/asm/kvm_host.h                    |  1 +
 arch/x86/kvm/cpuid.c                               |  2 +-
 arch/x86/kvm/svm/sev.c                             | 24 +++++++----
 arch/x86/kvm/svm/svm.c                             | 49 ++++++++++++++++++++++
 arch/x86/kvm/svm/svm.h                             |  2 +-
 arch/x86/kvm/svm/vmenter.S                         | 10 +----
 arch/x86/kvm/vmx/vmx.c                             |  8 +---
 arch/x86/kvm/vmx/vmx.h                             |  2 -
 arch/x86/kvm/x86.c                                 |  2 +
 tools/testing/selftests/kvm/mmu_stress_test.c      | 21 ++++++----
 .../selftests/kvm/x86/nested_exceptions_test.c     |  2 +
 tools/testing/selftests/kvm/x86/sev_smoke_test.c   |  3 +-
 12 files changed, 91 insertions(+), 35 deletions(-)

Re: [GIT PULL] KVM: x86: Fixes for 6.14-rcN

[Paolo Bonzini]

On Sat, Mar 8, 2025 at 2:03 AM Sean Christopherson <seanjc@google.com> wrote:
>
> Please pull a handful of fixes for 6.14.  The DEBUGCTL changes are the most
> urgent, as they fix a bug that was introduced in 6.13 that results in Steam
> (and other applications) getting killed due to unexpected #DBs.
>
> The following changes since commit c2fee09fc167c74a64adb08656cb993ea475197e:
>
>   KVM: x86: Load DR6 with guest value only before entering .vcpu_run() loop (2025-02-12 08:59:38 -0800)
>
> are available in the Git repository at:
>
>   https://github.com/kvm-x86/linux.git tags/kvm-x86-fixes-6.14-rcN.2
>
> for you to fetch changes up to f9dc8fb3afc968042bdaf4b6e445a9272071c9f3:
>
>   KVM: x86: Explicitly zero EAX and EBX when PERFMON_V2 isn't supported by KVM (2025-03-04 09:19:18 -0800)

Pulled, thanks.

Paolo

> ----------------------------------------------------------------
> KVM x86 fixes for 6.14-rcN #2
>
>  - Set RFLAGS.IF in C code on SVM to get VMRUN out of the STI shadow.
>
>  - Ensure DEBUGCTL is context switched on AMD to avoid running the guest with
>    the host's value, which can lead to unexpected bus lock #DBs.
>
>  - Suppress DEBUGCTL.BTF on AMD (to match Intel), as KVM doesn't properly
>    emulate BTF.  KVM's lack of context switching has meant BTF has always been
>    broken to some extent.
>
>  - Always save DR masks for SNP vCPUs if DebugSwap is *supported*, as the guest
>    can enable DebugSwap without KVM's knowledge.
>
>  - Fix a bug in mmu_stress_tests where a vCPU could finish the "writes to RO
>    memory" phase without actually generating a write-protection fault.
>
>  - Fix a printf() goof in the SEV smoke test that causes build failures with
>    -Werror.
>
>  - Explicitly zero EAX and EBX in CPUID.0x8000_0022 output when PERFMON_V2
>    isn't supported by KVM.
>
> ----------------------------------------------------------------
> Sean Christopherson (11):
>       KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the STI shadow
>       KVM: selftests: Assert that STI blocking isn't set after event injection
>       KVM: SVM: Drop DEBUGCTL[5:2] from guest's effective value
>       KVM: SVM: Suppress DEBUGCTL.BTF on AMD
>       KVM: x86: Snapshot the host's DEBUGCTL in common x86
>       KVM: SVM: Manually context switch DEBUGCTL if LBR virtualization is disabled
>       KVM: x86: Snapshot the host's DEBUGCTL after disabling IRQs
>       KVM: SVM: Save host DR masks on CPUs with DebugSwap
>       KVM: SVM: Don't rely on DebugSwap to restore host DR0..DR3
>       KVM: selftests: Ensure all vCPUs hit -EFAULT during initial RO stage
>       KVM: selftests: Fix printf() format goof in SEV smoke test
>
> Xiaoyao Li (1):
>       KVM: x86: Explicitly zero EAX and EBX when PERFMON_V2 isn't supported by KVM
>
>  arch/x86/include/asm/kvm_host.h                    |  1 +
>  arch/x86/kvm/cpuid.c                               |  2 +-
>  arch/x86/kvm/svm/sev.c                             | 24 +++++++----
>  arch/x86/kvm/svm/svm.c                             | 49 ++++++++++++++++++++++
>  arch/x86/kvm/svm/svm.h                             |  2 +-
>  arch/x86/kvm/svm/vmenter.S                         | 10 +----
>  arch/x86/kvm/vmx/vmx.c                             |  8 +---
>  arch/x86/kvm/vmx/vmx.h                             |  2 -
>  arch/x86/kvm/x86.c                                 |  2 +
>  tools/testing/selftests/kvm/mmu_stress_test.c      | 21 ++++++----
>  .../selftests/kvm/x86/nested_exceptions_test.c     |  2 +
>  tools/testing/selftests/kvm/x86/sev_smoke_test.c   |  3 +-
>  12 files changed, 91 insertions(+), 35 deletions(-)
>