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KVM: VMX: Drop guest CPUID check for VMXE in vmx_set_cr4()

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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 <stsp@users.sourceforge.net>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20201007014417.29276-2-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2020-10-06 18:44:12 -07:00 committed by Paolo Bonzini
parent c887c9b9ca
commit d3a9e4146a
1 changed files with 3 additions and 2 deletions
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5
arch/x86/kvm/vmx/vmx.c
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@ -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;
}