From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH] do not enter vcpu again if it was stopped during IO Date: Wed, 23 Jun 2010 12:16:46 +0200 Message-ID: <4C21DF0E.9080505@siemens.com> References: <20100621090152.GG4689@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: avi@redhat.com, mtosatti@redhat.com, kvm@vger.kernel.org To: Gleb Natapov Return-path: Received: from david.siemens.de ([192.35.17.14]:20167 "EHLO david.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752400Ab0FWKRD (ORCPT ); Wed, 23 Jun 2010 06:17:03 -0400 In-Reply-To: <20100621090152.GG4689@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Gleb Natapov wrote: > To prevent reentering vcpu after IO completion it is not enough > to set env->stopped since it is checked only in main loop but control > will not get there until next non-IO exit since kvm_run() will reenter > vcpu to complete IO instruction. Solve this by sending self-signal to > request exit after IO instruction completion. > > Signed-off-by: Gleb Natapov > diff --git a/qemu-kvm.c b/qemu-kvm.c > index be1dac2..4f7cf6d 100644 > --- a/qemu-kvm.c > +++ b/qemu-kvm.c > @@ -603,6 +603,10 @@ int kvm_run(CPUState *env) > r = pre_kvm_run(kvm, env); > if (r) > return r; > + if (env->exit_request) { > + env->exit_request = 0; > + pthread_kill(env->kvm_cpu_state.thread, SIG_IPI); > + } > r = ioctl(fd, KVM_RUN, 0); > > if (r == -1 && errno != EINTR && errno != EAGAIN) { > diff --git a/vl.c b/vl.c > index 9e9c176..dcfab13 100644 > --- a/vl.c > +++ b/vl.c > @@ -1817,6 +1817,7 @@ void qemu_system_reset_request(void) > } > if (cpu_single_env) { > cpu_single_env->stopped = 1; > + cpu_exit(cpu_single_env); > } > qemu_notify_event(); > } What does this second hunk do, specifically in the context of I/O processing? The changelog does not mention it explicitly (or I'm missing the obvious). Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux