diff options
| author | Jim Mattson <jmattson@google.com> | 2026-02-05 15:15:26 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-03-19 16:15:02 +0100 |
| commit | cb979700c40f592473704be14a8441b3a4451255 (patch) | |
| tree | 07fb116723d6f8bc7b3d1a6be4b32b0d5d7a3037 /Documentation/virt | |
| parent | 607f4da9731464d2dddc238e53437125c9771c7a (diff) | |
KVM: x86: Introduce KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM
commit e2ffe85b6d2bb7780174b87aa4468a39be17eb81 upstream.
Add KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM to allow L1 to set
FREEZE_IN_SMM in vmcs12's GUEST_IA32_DEBUGCTL field, as permitted
prior to commit 6b1dd26544d0 ("KVM: VMX: Preserve host's
DEBUGCTLMSR_FREEZE_IN_SMM while running the guest"). Enable the quirk
by default for backwards compatibility (like all quirks); userspace
can disable it via KVM_CAP_DISABLE_QUIRKS2 for consistency with the
constraints on WRMSR(IA32_DEBUGCTL).
Note that the quirk only bypasses the consistency check. The vmcs02 bit is
still owned by the host, and PMCs are not frozen during virtualized SMM.
In particular, if a host administrator decides that PMCs should not be
frozen during physical SMM, then L1 has no say in the matter.
Fixes: 095686e6fcb4 ("KVM: nVMX: Check vmcs12->guest_ia32_debugctl on nested VM-Enter")
Cc: stable@vger.kernel.org
Signed-off-by: Jim Mattson <jmattson@google.com>
Link: https://patch.msgid.link/20260205231537.1278753-1-jmattson@google.com
[sean: tag for stable@, clean-up and fix goofs in the comment and docs]
Signed-off-by: Sean Christopherson <seanjc@google.com>
[Rename quirk. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/virt')
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index f1f1d2e5dc7c..b1008283e11d 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -8438,6 +8438,14 @@ KVM_X86_QUIRK_IGNORE_GUEST_PAT By default, on Intel platforms, KVM ignores guest software, for example if it does not expose a bochs graphics device (which is known to have had a buggy driver). + +KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM By default, KVM relaxes the consistency + check for GUEST_IA32_DEBUGCTL in vmcs12 + to allow FREEZE_IN_SMM to be set. When + this quirk is disabled, KVM requires this + bit to be cleared. Note that the vmcs02 + bit is still completely controlled by the + host, regardless of the quirk setting. =================================== ============================================ 7.32 KVM_CAP_MAX_VCPU_ID |