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Re: [Xen-devel] [PATCH 10/13] Nested Virtualization: interrupts (svm specific)


  • To: Tim Deegan <Tim.Deegan@xxxxxxxxxx>, Christoph Egger <Christoph.Egger@xxxxxxx>
  • From: Keir Fraser <keir@xxxxxxx>
  • Date: Tue, 16 Nov 2010 15:45:52 +0000
  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Tue, 16 Nov 2010 07:46:37 -0800
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  • Thread-topic: [Xen-devel] [PATCH 10/13] Nested Virtualization: interrupts (svm specific)

On 16/11/2010 15:06, "Tim Deegan" <Tim.Deegan@xxxxxxxxxx> wrote:

>> +static int
>> +nestedsvm_vcpu_clgi(struct vcpu *v)
>> +{
>> +    struct nestedsvm *svm = &vcpu_nestedsvm(v);
>> +
>> +    /* clear gif flag */
>> +    svm->ns_gif = 0;
>> +    local_event_delivery_disable(); /* mask events for PV drivers */
> 
> This function, and the stgi one below, can only operate safely on
> current; if you want to keep the argument for performance then maybe
> ASSERT(v == current) for sanity.

I don't believe in the performance win. Functions which act correctly only
on current should not be passed a vcpu parameter.

 -- Keir



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