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KVM: x86: Reinitialize context if host userspace toggles EFER.LME

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commit d617429936 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: 11988499e6 ("KVM: x86: Skip EFER vs. guest CPUID checks for host-initiated writes")
Cc: stable@vger.kernel.org
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Paolo Bonzini 2022-02-09 04:56:05 -05:00 committed by Greg Kroah-Hartman
parent 273ad0cf56
commit 48306afcac
2 changed files with 2 additions and 2 deletions
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1
arch/x86/kvm/mmu.h
View file

@ -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)
{

3
arch/x86/kvm/x86.c
View file

@ -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;