linux-kernel - Re: [PATCHv4 3/5] kvm: host side for eoi optimization

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Date:	Thu, 17 May 2012 12:24:30 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Gleb Natapov <gleb@...hat.com>
CC:	"Michael S. Tsirkin" <mst@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>, x86@...nel.org,
	kvm@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4 3/5] kvm: host side for eoi optimization

On 05/17/2012 11:07 AM, Gleb Natapov wrote:
> > 
> > No, let's refactor this so it makes sense.  The {has|get}_interrupt
> > split is the cause of the problem, I think.  We need a single function,
> > with callbacks that are called when an event happens.  The callbacks can
> > request an irq window exit, inject an interrupt, play with pveoi, or
> > cause a #vmexit.
> > 
> Not sure what do you mean here. I kind of like the code we have now, but
> this may be because I understand it :)

Right now we have

   if (has_interrupt)
       do something
   if (get_interrupt)
       do_something_else

this duplicates some of the logic and causes non-atomicty (which isn't a
problem per se, but requires us to think of what happens if conditions
change between the two steps).

What I'm thinking of is

   void process_interrupt(bool (*handle)());

Where the return value tells us whether the interrupt was accepted by
the handler.  The callback could decide to enable the irq window, to
queue the interrupt, or to #vmexit (note that the latter can return
either true or false, depending on whether vmx is configured to ack the
interrupt or not; svm would return true here if interrupts are intercepted).

-- 
error compiling committee.c: too many arguments to function

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