Re: [PATCH] KVM: VMX: simplify NMI mask management

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-03-23 14:12, Avi Kivity wrote:
> Use vmx_set_nmi_mask() instead of open-coding management of
> the hardware bit and the software hint (nmi_known_unmasked).
> 
> There's a slight change of behaviour when running without
> hardware virtual NMI support - we now clear the NMI mask if
> NMI delivery faulted in that case as well.  This improves
> emulation accuracy.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>
> ---
>  arch/x86/kvm/vmx.c |   10 ++--------
>  1 files changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 1bdb49d..2b99ae7 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3532,11 +3532,7 @@ static int handle_task_switch(struct kvm_vcpu *vcpu)
>  		switch (type) {
>  		case INTR_TYPE_NMI_INTR:
>  			vcpu->arch.nmi_injected = false;
> -			if (cpu_has_virtual_nmis()) {
> -				vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
> -					      GUEST_INTR_STATE_NMI);
> -				vmx->nmi_known_unmasked = false;
> -			}
> +			vmx_set_nmi_mask(vcpu, true);
>  			break;
>  		case INTR_TYPE_EXT_INTR:
>  		case INTR_TYPE_SOFT_INTR:
> @@ -3991,9 +3987,7 @@ static void __vmx_complete_interrupts(struct vcpu_vmx *vmx,
>  		 * Clear bit "block by NMI" before VM entry if a NMI
>  		 * delivery faulted.
>  		 */
> -		vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO,
> -				GUEST_INTR_STATE_NMI);
> -		vmx->nmi_known_unmasked = true;
> +		vmx_set_nmi_mask(&vmx->vcpu, false);
>  		break;
>  	case INTR_TYPE_SOFT_EXCEPTION:
>  		vmx->vcpu.arch.event_exit_inst_len =

Looks consistent to me, but maybe you should update the comment above
that's now also applied to the emulated mask.

Jan

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