From d3a9e4146a6f79f19430bca3f2a4d6ebaaffe36b Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 6 Oct 2020 18:44:12 -0700 Subject: [PATCH] KVM: VMX: Drop guest CPUID check for VMXE in vmx_set_cr4() Drop vmx_set_cr4()'s somewhat hidden guest_cpuid_has() check on VMXE now that common x86 handles the check by incorporating VMXE into the CR4 reserved bits, i.e. in cr4_guest_rsvd_bits. This fixes a bug where KVM incorrectly rejects KVM_SET_SREGS with CR4.VMXE=1 if it's executed before KVM_SET_CPUID{,2}. Fixes: 5e1746d6205d ("KVM: nVMX: Allow setting the VMXE bit in CR4") Reported-by: Stas Sergeev Signed-off-by: Sean Christopherson Message-Id: <20201007014417.29276-2-sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/vmx.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 47b8357b9751..7ebf08db6747 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -3129,9 +3129,10 @@ int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) * must first be able to turn on cr4.VMXE (see handle_vmon()). * So basically the check on whether to allow nested VMX * is here. We operate under the default treatment of SMM, - * so VMX cannot be enabled under SMM. + * so VMX cannot be enabled under SMM. Note, guest CPUID is + * intentionally ignored, it's handled by cr4_guest_rsvd_bits. */ - if (!nested_vmx_allowed(vcpu) || is_smm(vcpu)) + if (!nested || is_smm(vcpu)) return 1; } -- GitLab