[PATCH v3 06/11] KVM: x86/mmu: move TDP zaps from guest MTRRs update to CR0.CD toggling

[Yan Zhao]

If guest MTRRs are honored, always zap TDP when CR0.CD toggles and don't do
it if guest MTRRs are updated under CR0.CD=1.

This is because CR0.CD=1 takes precedence over guest MTRRs to decide TDP
memory types, TDP memtypes are not changed if guest MTRRs update under
CR0.CD=1.

Instead, always do the TDP zapping when CR0.CD toggles, because even with
the quirk KVM_X86_QUIRK_CD_NW_CLEARED, TDP memory types may change after
guest CR0.CD toggles.

Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
---
 arch/x86/kvm/mtrr.c | 3 +++
 arch/x86/kvm/x86.c  | 3 +--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
index a67c28a56417..3ce58734ad22 100644
--- a/arch/x86/kvm/mtrr.c
+++ b/arch/x86/kvm/mtrr.c
@@ -323,6 +323,9 @@ static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
 	if (!kvm_mmu_honors_guest_mtrrs(vcpu->kvm))
 		return;
 
+	if (kvm_is_cr0_bit_set(vcpu, X86_CR0_CD))
+		return;
+
 	if (!mtrr_is_enabled(mtrr_state) && msr != MSR_MTRRdefType)
 		return;
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ac9548efa76f..32cc8bfaa5f1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -942,8 +942,7 @@ void kvm_post_set_cr0(struct kvm_vcpu *vcpu, unsigned long old_cr0, unsigned lon
 		kvm_mmu_reset_context(vcpu);
 
 	if (((cr0 ^ old_cr0) & X86_CR0_CD) &&
-	    kvm_mmu_honors_guest_mtrrs(vcpu->kvm) &&
-	    !kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED))
+	    kvm_mmu_honors_guest_mtrrs(vcpu->kvm))
 		kvm_zap_gfn_range(vcpu->kvm, 0, ~0ULL);
 }
 EXPORT_SYMBOL_GPL(kvm_post_set_cr0);
-- 
2.17.1