From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60758) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bAvFy-0007fq-2m for qemu-devel@nongnu.org; Thu, 09 Jun 2016 04:24:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bAvFt-0005x1-3L for qemu-devel@nongnu.org; Thu, 09 Jun 2016 04:24:02 -0400 Received: from mail-wm0-x244.google.com ([2a00:1450:400c:c09::244]:34985) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bAvFs-0005wB-So for qemu-devel@nongnu.org; Thu, 09 Jun 2016 04:23:57 -0400 Received: by mail-wm0-x244.google.com with SMTP id k184so8608999wme.2 for ; Thu, 09 Jun 2016 01:23:56 -0700 (PDT) Sender: Paolo Bonzini References: <20160603060944.17373-1-haozhong.zhang@intel.com> <20160603060944.17373-3-haozhong.zhang@intel.com> <20160609071624.6nfqeils2vr2mp73@hz-desktop> From: Paolo Bonzini Message-ID: <7f4890ef-d305-aec9-ca78-342ddda13aa8@redhat.com> Date: Thu, 9 Jun 2016 10:23:52 +0200 MIME-Version: 1.0 In-Reply-To: <20160609071624.6nfqeils2vr2mp73@hz-desktop> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 2/2] target-i386: add migration support for Intel LMCE List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, Richard Henderson , Eduardo Habkost , Marcelo Tosatti , "Michael S . Tsirkin" , kvm@vger.kernel.org, Boris Petkov , Tony Luck , Andi Kleen , Ashok Raj On 09/06/2016 09:16, Haozhong Zhang wrote: > On 06/08/16 13:36, Paolo Bonzini wrote: >> >> >> On 03/06/2016 08:09, Haozhong Zhang wrote: >>> LMCE is disabled by default, but a cpu option 'lmce=on/off' is provided >>> to enable/disable it. Migration is only allowed between VCPUs with the >>> same lmce option. >> >> This is not needed at all if you do the change in patch 1 that Eduardo >> requested (refuse to start if the host doesn't have the required >> capabilities). >> >> So if you do that you can just move the lmce property to patch 1. >> > > But it doesn't cover the migration from lmce-enabled qemu to > lmce-disabled qemu where KVM on both hosts support LMCE. That's a configuration problem; configuration is not migrated and is assumed to be the same on the source and the destination. You don't need to test for this scenario. Paolo In that case, > both qemu can start without failure, but the guest OS will run in a VM > with different configurations after migration. To avoid this, I didn't > leave the lmce property in patch 1, so that users have no way to > enable LMCE without this patch 2.