From a506fdd22342606d22645a6bf90a2d848e92e5d7 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Fri, 10 Jul 2020 16:11:55 +0200 Subject: KVM: nSVM: implement nested_svm_load_cr3() and use it for host->guest switch Undesired triple fault gets injected to L1 guest on SVM when L2 is launched with certain CR3 values. #TF is raised by mmu_check_root() check in fast_pgd_switch() and the root cause is that when kvm_set_cr3() is called from nested_prepare_vmcb_save() with NPT enabled CR3 points to a nGPA so we can't check it with kvm_is_visible_gfn(). Using generic kvm_set_cr3() when switching to nested guest is not a great idea as we'll have to distinguish between 'real' CR3s and 'nested' CR3s to e.g. not call kvm_mmu_new_pgd() with nGPA. Following nVMX implement nested-specific nested_svm_load_cr3() doing the job. To support the change, nested_svm_load_cr3() needs to be re-ordered with nested_svm_init_mmu_context(). Note: the current implementation is sub-optimal as we always do TLB flush/MMU sync but this is still an improvement as we at least stop doing kvm_mmu_reset_context(). Fixes: 7c390d350f8b ("kvm: x86: Add fast CR3 switch code path") Signed-off-by: Vitaly Kuznetsov Message-Id: <20200710141157.1640173-8-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/kvm/mmu/mmu.c') diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 78c88e8aecfa..61c35fec5219 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4952,6 +4952,8 @@ void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, u32 cr0, u32 cr4, u32 efer, union kvm_mmu_role new_role = kvm_calc_shadow_mmu_root_page_role(vcpu, false); + __kvm_mmu_new_pgd(vcpu, nested_cr3, new_role.base, false, false); + if (new_role.as_u64 != context->mmu_role.as_u64) shadow_mmu_init_context(vcpu, context, cr0, cr4, efer, new_role); } -- cgit v1.2.3