diff options
| author | Sean Christopherson <seanjc@google.com> | 2021-02-12 16:50:08 -0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-02-19 03:08:33 -0500 |
| commit | 2855f98265dc579bd2becb79ce0156d08e0df813 (patch) | |
| tree | c2000339d633bed93401a646168acd6cc94d0afe /arch/x86 | |
| parent | c3bb9a20834ffe72d3031afe460ff03d3b3b6e90 (diff) | |
KVM: x86/mmu: Expand on the comment in kvm_vcpu_ad_need_write_protect()
Expand the comment about need to use write-protection for nested EPT
when PML is enabled to clarify that the tagging is a nop when PML is
_not_ enabled. Without the clarification, omitting the PML check looks
wrong at first^Wfifth glance.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/mmu/mmu_internal.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h index 0b55aa561ec8..72b0928f2b2d 100644 --- a/arch/x86/kvm/mmu/mmu_internal.h +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -84,7 +84,10 @@ static inline bool kvm_vcpu_ad_need_write_protect(struct kvm_vcpu *vcpu) * When using the EPT page-modification log, the GPAs in the log * would come from L2 rather than L1. Therefore, we need to rely * on write protection to record dirty pages. This also bypasses - * PML, since writes now result in a vmexit. + * PML, since writes now result in a vmexit. Note, this helper will + * tag SPTEs as needing write-protection even if PML is disabled or + * unsupported, but that's ok because the tag is consumed if and only + * if PML is enabled. Omit the PML check to save a few uops. */ return vcpu->arch.mmu == &vcpu->arch.guest_mmu; } |