This is a note to let you know that I've just added the patch titled
KVM: VMX: Drop guest CPUID check for VMXE in vmx_set_cr4()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-vmx-drop-guest-cpuid-check-for-vmxe-in-vmx_set_c.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cd8244785a8b7d8f6440b7ddff0a495d17f9fc1d
Author: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Tue Oct 6 18:44:12 2020 -0700
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 <stsp@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Message-Id: <20201007014417.29276-2-sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 9b520da3f748..1b75847d8a49 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;
}
