Commit d3a9e414 authored Oct 06, 2020 by Sean Christopherson Committed by Paolo Bonzini Nov 15, 2020

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: 5e1746d6 ("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>

parent c887c9b9

arch/x86/kvm/vmx/vmx.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}

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