From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: questions about ack_intr_on_exit and preemption hooks Date: Tue, 17 Jul 2007 17:08:00 +0300 Message-ID: <469CCD40.5040806@qumranet.com> References: <20070712203417.GC28354@frankl.hpl.hp.com> <46972170.6000108@qumranet.com> <20070717132508.GB13171@frankl.hpl.hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: eranian-sDzT885Ts8HQT0dZR+AlfA@public.gmane.org Return-path: In-Reply-To: <20070717132508.GB13171-HU54gidqsKnWxDs0y9d3MAC/G2K4zDHf@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Stephane Eranian wrote: > Avi, > > On Fri, Jul 13, 2007 at 09:53:36AM +0300, Avi Kivity wrote: > >> Stephane Eranian wrote: >> >>> Avi, >>> >>> A couple of months back, we had a discussion about PMU virtualization >>> and the difficulty I encountered trying to catch the PMU interrupt >>> vector in kvm on VM-exit. KVM does not set ack_intr_on_intr. Would >>> you mind reminding me of the reason for this? >>> >>> >>> >> If we ack the interrupt, we have to dispatch it ourselves, most likely >> by faking an 'int $xx' instruction. >> >> By not acking the interrupt, we allow it do be delivered through the >> host IDT whether we are in guest mode or not. >> >> > Doesn't that assume that any interrupt generated by the guest has a > host IDT entry? > > Right now we don't allow the guest access to the hardware, so the guest can't generate any interrupt. > On a related issue, you set NMI_EXITING. Why is that? Assuming the > guest does not use the NMI watchdog. Are you doing this to ensure > that the host NMI watchdog keeps on going while you're executing > in the guest? > Yes. Or oprofile. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/