Re: [Xen-devel] Virtual Interrupt Delivery

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx]
> Sent: Thursday, March 02, 2017 4:36 AM
> 
> On Mon, Feb 27, 2017 at 09:13:29PM +0300, Dmitry Rockosov wrote:
> > Hi guys,
> >
> > Do you know when *recognized* Virtual Interrupt on VM-Entry will be
> > delivered if Virtual-Interrupt Delivery is enabled and interrupt delivery
> > is blocking by STI?
> 
> This sounds like a good question to the Intel maintainers, CC-ing them.

virtual interrupt delivery doesn't change the implication of blocking
by STI. It will be evaluated and delivered when it's allowed.

> 
> >
> > Previously, VMM used Interrupt-Window, but as I see in XEN code,
> > Interrupt-Window
> > is not used when Virtual Interrupt Delivery is enabled.
> 
> Right, the Intel SDM has a whole section about that.
> >
> > Does it mean, we will get Virtual Interrupt on the next VM-entry?
> 
> By my understanding of the Intel SDM it depends on whether the
> vector is one of those that the CPU can inject without involving
> the VMM.
> 
> I would recommend you read the Intel SDM - the answer may be right
> there.

yes SDM has a very clear description of when a virtual interrupt 
delivery will happen. check CH29.2 (Evaluation and Delivery of
Virtual Interrupts).

Thanks
Kevin

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