Re: [PATCH] KVM: Don't mistreat edge-triggered INIT IPI as INIT de-assert. (LAPIC)

[Marcelo Tosatti <mtosatti@redhat.com>]

On Mon, Dec 19, 2011 at 02:14:27AM +0100, Julian Stecklina wrote:
> If the guest programs an IPI with level=0 (de-assert) and trig_mode=0 (edge),
> it is erroneously treated as INIT de-assert and ignored, but to quote the
> spec: "For this delivery mode [INIT de-assert], the level flag must be set to
> 0 and trigger mode flag to 1."

Yes, the implementation ignores INIT de-assert. Quoting the spec:

"(INIT Level De-assert) (Not supported in the Pentium 4 and Intel Xeon
processors.)"

Your patch below is not improving the implementation to be closer to the
spec: it'll trigger the INIT state initialization with trig_mode == 0
(which is not in accordance with your spec quote above).

> Signed-off-by: Julian Stecklina <js@alien8.de>
> ---
>  arch/x86/kvm/lapic.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index a7f3e65..260770d 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -433,7 +433,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
>  		break;
>  
>  	case APIC_DM_INIT:
> -		if (level) {
> +		if (!trig_mode || level) {
>  			result = 1;
>  			vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
>  			kvm_make_request(KVM_REQ_EVENT, vcpu);
> -- 
> 1.7.7.4
> 
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