From 3d462e3287f98724e577fccfbb8510627bd55470 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 9 Feb 2022 04:56:05 -0500 Subject: [PATCH] KVM: x86: Reinitialize context if host userspace toggles EFER.LME BugLink: https://bugs.launchpad.net/bugs/1969110 commit d6174299365ddbbf491620c0b8c5ca1a6ef2eea5 upstream. While the guest runs, EFER.LME cannot change unless CR0.PG is clear, and therefore EFER.NX is the only bit that can affect the MMU role. However, set_efer accepts a host-initiated change to EFER.LME even with CR0.PG=1. In that case, the MMU has to be reset. Fixes: 11988499e62b ("KVM: x86: Skip EFER vs. guest CPUID checks for host-initiated writes") Cc: stable@vger.kernel.org Reviewed-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 48306afcac2a027163c6a8d10bd7a1d9d10efe37) Signed-off-by: Paolo Pisati --- arch/x86/kvm/mmu.h | 1 + arch/x86/kvm/x86.c | 3 +-- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index e9688a9f7b57..7bb165c23233 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -49,6 +49,7 @@ X86_CR4_LA57) #define KVM_MMU_CR0_ROLE_BITS (X86_CR0_PG | X86_CR0_WP) +#define KVM_MMU_EFER_ROLE_BITS (EFER_LME | EFER_NX) static __always_inline u64 rsvd_bits(int s, int e) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 52e4f6110aec..50ac0854575e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1605,8 +1605,7 @@ static int set_efer(struct kvm_vcpu *vcpu, struct msr_data *msr_info) return r; } - /* Update reserved bits */ - if ((efer ^ old_efer) & EFER_NX) + if ((efer ^ old_efer) & KVM_MMU_EFER_ROLE_BITS) kvm_mmu_reset_context(vcpu); return 0; -- 2.39.5