KVM: x86/mmu: Ignore guest CR3 on fast root switch for direct MMU (3651c7fc) · Commits · 戴 / test

Ignore the guest's CR3 when looking for a cached root for a direct MMU, the guest's CR3 has no impact on the direct MMU's shadow pages (the role check ensures compatibility with CR0.WP, etc...). Zero out root_cr3 when allocating the direct roots to make it clear that it's ignored. Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by:

Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -3730,7 +3730,9 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
		vcpu->arch.mmu->root_hpa = __pa(vcpu->arch.mmu->pae_root);
		} else
		BUG();
		vcpu->arch.mmu->root_cr3 = vcpu->arch.mmu->get_cr3(vcpu);

		/* root_cr3 is ignored for direct MMUs. */
		vcpu->arch.mmu->root_cr3 = 0;

		return 0;
		}
		@@ -4272,8 +4274,8 @@ static bool cached_root_available(struct kvm_vcpu *vcpu, gpa_t new_cr3,
		for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) {
		swap(root, mmu->prev_roots[i]);

		if (new_cr3 == root.cr3 && VALID_PAGE(root.hpa) &&
		page_header(root.hpa) != NULL &&
		if ((new_role.direct \|\| new_cr3 == root.cr3) &&
		VALID_PAGE(root.hpa) && page_header(root.hpa) &&
		new_role.word == page_header(root.hpa)->role.word)
		break;
		}

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