Re: [PATCH 17/28] KVM: nVMX: pass PFERR_USER_MASK to MMU on EPT violations

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> For EPT, PFERR_USER_MASK refers not to the CPL of the guest,
> but to the AND of the U bits encountered while walking guest
> page tables; this is consistent with how MBEC differentiates
> between XS and XU.  This is available through the
> "advanced vmexit information for EPT violations" feature.
> 
> Tested-by: David Riley <d.riley@xxxxxxxxxxx>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
>  arch/x86/kvm/vmx/common.h |  6 +++++-
>  arch/x86/kvm/vmx/vmx.c    | 10 ++++++++++
>  2 files changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
> index 40fa72f31fc7..48520fa1c8e8 100644
> --- a/arch/x86/kvm/vmx/common.h
> +++ b/arch/x86/kvm/vmx/common.h
> @@ -100,9 +100,13 @@ static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
>  		error_code |= (exit_qualification & EPT_VIOLATION_PROT_USER_EXEC)
>  			      ? PFERR_PRESENT_MASK : 0;
>  
> -	if (exit_qualification & EPT_VIOLATION_GVA_IS_VALID)
> +	if (exit_qualification & EPT_VIOLATION_GVA_IS_VALID) {
>  		error_code |= (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) ?
>  			      PFERR_GUEST_FINAL_MASK : PFERR_GUEST_PAGE_MASK;
> +		if ((exit_qualification & (EPT_VIOLATION_GVA_TRANSLATED|EPT_VIOLATION_GVA_USER))
> +		    == (EPT_VIOLATION_GVA_TRANSLATED|EPT_VIOLATION_GVA_USER))

Ow.  Maybe add a helper or a local const u64?  Actually, no need, just drop the
ternary operator above:

	if (exit_qualification & EPT_VIOLATION_GVA_IS_VALID) {
		if (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) {
			error_code |= PFERR_GUEST_FINAL_MASK;
			if (exit_qualification & EPT_VIOLATION_GVA_USER)
				error_code |= PFERR_USER_MASK;
		} else {
			error_code |= PFERR_GUEST_PAGE_MASK;
		}
	}