From 3651c7fc2bf63b62c009b8470aaf096b3b4b01e8 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 28 Feb 2020 14:52:39 -0800 Subject: [PATCH] KVM: x86/mmu: Ignore guest CR3 on fast root switch for direct MMU 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 Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index c4e0b97f82ac..9d617b9dc78f 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -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; }