From mboxrd@z Thu Jan 1 00:00:00 1970 From: Glauber Costa Subject: Re: [PATCH 1/4] always halt non-bsp cpu. Date: Tue, 2 Jun 2009 22:01:59 -0300 Message-ID: <20090603010159.GA30777@poweredge.glommer> References: <1243971470-31676-1-git-send-email-glommer@redhat.com> <1243971470-31676-2-git-send-email-glommer@redhat.com> <4A258D23.9080106@web.de> <20090602212340.GX30777@poweredge.glommer> <4A25A11C.3090700@web.de> <20090602220937.GY30777@poweredge.glommer> <4A25A864.2070006@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, avi@redhat.com To: Jan Kiszka Return-path: Received: from mx2.redhat.com ([66.187.237.31]:46290 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752705AbZFCA4N (ORCPT ); Tue, 2 Jun 2009 20:56:13 -0400 Content-Disposition: inline In-Reply-To: <4A25A864.2070006@web.de> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Jun 03, 2009 at 12:32:04AM +0200, Jan Kiszka wrote: > Glauber Costa wrote: > > On Wed, Jun 03, 2009 at 12:01:00AM +0200, Jan Kiszka wrote: > >> Glauber Costa wrote: > >>> On Tue, Jun 02, 2009 at 10:35:47PM +0200, Jan Kiszka wrote: > >>>> Glauber Costa wrote: > >>>>> This is not kvm specific, and should do fine in plain qemu > >>>> This is fine with plain qemu already. The problem, IIUC, is that > >>>> in-kernel kvm irqchip does not have a chance to remove the halted state > >>>> again. Did you test the effect of this patch on that scenario? What > >>>> makes it safe to be removed now? > >>> IIRC, the in kernel irqchip sets halted = 0 in the very beginning of > >>> the vcpu initialization. > >>> > >>> It is tested here with in-kernel irqchip and works, so probably not > >>> a problem, unless you can spot something. > >> At least your patch applied alone breaks -smp >1 here. > >> > >> But the whole management of env->halted for the in-kernel irqchip in > >> qemu-kvm is a bit hacky IMHO. Maybe it's time to rethink this. Would be > >> nice to always see a consistent halted in user space, specifically for > >> debugging purposes. > > out of curiosity: did you apply the whole series? > > Meanwhile I did, but it makes no difference. Jan, can you be more specific on why it breaks? I'm double trying it here, and it works for me just fine.