From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM: don't sent IPI if the vcpu is not online Date: Mon, 06 Sep 2010 11:55:07 +0300 Message-ID: <4C84AC6B.4090306@redhat.com> References: <4C807593.1050903@cn.fujitsu.com> <4C83445B.4020103@redhat.com> <4C844887.9090802@cn.fujitsu.com> <4C84801F.9060803@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Xiao Guangrong , Marcelo Tosatti , LKML , KVM To: Alexander Graf Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 09/06/2010 11:51 AM, Alexander Graf wrote: > >> I think guest_mode makes sense for the other archs for reducing IPIs, so let's leave it common and recommend that they implement it. Alex, if you're ever bored. > What does the bit do? Do we have documentation on it ;)? No seriously, what's the intent of the field? > It indicates that the vcpu is currently executing guest code. Which in turn is important if you need to force it out of guest mode in order to inject an interrupt or flush the tlb. The procedure is: remote: - queue a request in vcpu->requests - IPI vcpu->cpu (new: only if in guest_mode) vcpu: - set guest_mode - dequeue and execute requests in vcpu->requests - enter guest - clear guest_mode -- error compiling committee.c: too many arguments to function