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e2ffe85b6d
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 commit6b1dd26544("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:095686e6fc("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>