From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41749) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WnS7j-0005JQ-Ak for qemu-devel@nongnu.org; Thu, 22 May 2014 08:29:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WnS7b-0005VK-H3 for qemu-devel@nongnu.org; Thu, 22 May 2014 08:29:27 -0400 Received: from e06smtp17.uk.ibm.com ([195.75.94.113]:42798) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WnS7b-0005U2-90 for qemu-devel@nongnu.org; Thu, 22 May 2014 08:29:19 -0400 Received: from /spool/local by e06smtp17.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 22 May 2014 13:29:16 +0100 Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 113622190042 for ; Thu, 22 May 2014 13:29:04 +0100 (BST) Received: from d06av06.portsmouth.uk.ibm.com (d06av06.portsmouth.uk.ibm.com [9.149.37.217]) by b06cxnps4075.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s4MCTDbJ54198286 for ; Thu, 22 May 2014 12:29:13 GMT Received: from d06av06.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av06.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s4MDTDvG024836 for ; Thu, 22 May 2014 07:29:13 -0600 Date: Thu, 22 May 2014 14:29:09 +0200 From: Michael Mueller Message-ID: <20140522142909.13fcd583@bee> In-Reply-To: <537DBB12.6070108@redhat.com> References: <1399993114-15333-1-git-send-email-mimu@linux.vnet.ibm.com> <1399993114-15333-7-git-send-email-mimu@linux.vnet.ibm.com> <5375FFB8.90504@suse.de> <20140516173907.3b1c4efa@bee> <53767590.2090605@suse.de> <20140519125339.09840b9e@bee> <5379EF78.9040209@suse.de> <20140519161811.5a17bc66@bee> <537A19F8.4060209@suse.de> <20140519190318.6f92c1bd@bee> <537A6608.8000608@suse.de> <20140520120218.38eb7181@bee> <537B2A0F.1030706@suse.de> <20140521145652.197bff21@bee> <537CA89B.6050803@suse.de> <20140522102316.653f34ba@bee> <537DBB12.6070108@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v1 RFC 6/6] KVM: s390: add cpu model support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: linux-s390@vger.kernel.org, qemu-devel@nongnu.org, Eduardo Habkost , kvm@vger.kernel.org, Gleb Natapov , linux-kernel@vger.kernel.org, Alexander Graf , Christian Borntraeger , "Jason J. Herne" , Cornelia Huck , Andreas Faerber , Richard Henderson On Thu, 22 May 2014 10:53:38 +0200 Paolo Bonzini wrote: > Il 22/05/2014 10:23, Michael Mueller ha scritto: > > On Wed, 21 May 2014 15:22:35 +0200 > > Alexander Graf wrote: > > > > I have seen the slides from Eduardo which he presented during this years > > DevConf in Brno and made my comments according the s390x implementation > > on that. Is you will see, this is mostly overlapping except for the model > > definition authority that I clearly see on qemu's side. > > > > See pdf attachment. > > More comments: > > - "Only one machine type in s390 case which is -machine s390-virtio-ccw" > > This probably should change sooner or later, as soon as the > implementation becomes stable enough. Versioning is necessary for live > migration across different QEMU version. Perhaps start versioning in > 2.2, i.e. start making s390-virtio-ccw-2.1 an alias for s390-virtio-ccw now? Absolutely right, we did not do it yet. > > Note that new virtio device features can appear at any time outside the > s390 code, and will take part in versioning as well. These changes are then as well included in the machine version I guess. > > - "No enforce option" > > Strongly suggest making enforce the only possible behavior. Right that's the plan. > > - "Not in the s390x case, because the KVM facility mask limits the cpu > model specific facilities" > > What if the KVM facility mask changes? For x86, nowadays new CPUID bits > are only introduced in KVM when a new processors comes out. But if we > introduced an older CPUID bit, it would be a huge complication for > backwards compatibility. Is it different for s390? > I'm thinking about this one currently. The ABI itself will not change because all facilities of the architecture will be defined in QEMU for the respective CPU model even though some of them are masked out upon request by KVM, but the mask is part of the interface itself and can be applied by QEMU already. Michael > Paolo >