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Re: [Xen-devel] [PATCH] hvm/vpt: Check that an irq is not blocked before

To: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] hvm/vpt: Check that an irq is not blocked before waking the vcpu
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 09 Mar 2009 12:01:58 +0000
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Thread-topic: [Xen-devel] [PATCH] hvm/vpt: Check that an irq is not blocked before waking the vcpu
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On 09/03/2009 11:45, "George Dunlap" <George.Dunlap@xxxxxxxxxxxxx> wrote:

> Currently, when a timer fires for a vpt interrupt, the interrupt
> handler calls vcpu_kick() without checking to see if the IRQ is
> blocked.  This causes the vcpu to wake up out of a halt when it
> shouldn't.
> 
> Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

Only one question: could this race an unmask operation? Before this patch,
pt_irq_masked() is only executed for the local vcpu, so such races may not
have been considered.

 -- Keir



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