From: Sean Christopherson Date: Wed, 7 Oct 2020 01:44:12 +0000 (-0700) Subject: KVM: VMX: Drop guest CPUID check for VMXE in vmx_set_cr4() X-Git-Tag: v5.10.137~47 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8b8b376903b32d3d854f39eeebe018169c920cb6;p=thirdparty%2Fkernel%2Fstable.git KVM: VMX: Drop guest CPUID check for VMXE in vmx_set_cr4() [ Upstream commit d3a9e4146a6f79f19430bca3f2a4d6ebaaffe36b ] 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 Signed-off-by: Sasha Levin --- diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 9b520da3f7488..1b75847d8a492 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -3217,9 +3217,10 @@ 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; }