RE: [Xen-devel] evtchn_upcall_mask for PV-on-HVM

To:	"Keir Fraser" <keir@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject:	RE: [Xen-devel] evtchn_upcall_mask for PV-on-HVM
From:	"Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date:	Thu, 30 Nov 2006 21:56:11 +0800
Cc:	"Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>
Delivery-date:	Thu, 30 Nov 2006 05:56:39 -0800
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Thread-topic:	[Xen-devel] evtchn_upcall_mask for PV-on-HVM

>From: Keir Fraser [mailto:keir@xxxxxxxxxxxxx]
>Sent: 2006年11月30日 17:09
>
>On 30/11/06 07:05, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
>
>> Anyway, we'd like to know whether this is a real bug. If yes, it may
>> have some impact on performance, and then people may clear the
>> evtchn_upcall_mask either at domain creation time or at callback_irq
>> setting time. In any case, this field does nothing for HVM domain since
>> the latter already has 'rflags.if' for same purpose.
>
>Local_events_need_delivery() should check for pending APIC/PIC
>interrupts on
>HVM. That'll fix the block() wakeup-waiting race too.
>
> -- Keir

Hi, Keir,
        Sorry that I didn't quite catch you. Did you mean check for 
pending interrupts for same gsi line (used as callback irq)? Whether 
to actually pending an irq instance is decided by APIC/PIC themselves, 
right? Vmx_intr_assit just needs to check status of 
evtchn_upcall_pending which serves as a virtual wire state. BTW, 
what's the block() wakeup-waiting race above? :-)

Thanks,
Kevin

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