From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Mueller Subject: Re: [PATCH v4 11/15] target-s390x: New QMP command query-cpu-model Date: Tue, 31 Mar 2015 22:09:09 +0200 Message-ID: <20150331220909.4410e8c0@bee> References: <1427725708-52100-1-git-send-email-mimu@linux.vnet.ibm.com> <1427725708-52100-12-git-send-email-mimu@linux.vnet.ibm.com> <20150331183526.GJ7031@thinpad.lan.raisama.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-s390@vger.kernel.org, kvm@vger.kernel.org, Gleb Natapov , linux-kernel@vger.kernel.org, Alexander Graf , qemu-devel@nongnu.org, Christian Borntraeger , Daniel Hansel , "Jason J. Herne" , Cornelia Huck , Paolo Bonzini , Andreas Faerber , Richard Henderson To: Eduardo Habkost Return-path: In-Reply-To: <20150331183526.GJ7031@thinpad.lan.raisama.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org On Tue, 31 Mar 2015 15:35:26 -0300 Eduardo Habkost wrote: > On Mon, Mar 30, 2015 at 04:28:24PM +0200, Michael Mueller wrote: > > This patch implements a new QMP request named 'query-cpu-model'. > > It returns the cpu model of cpu 0 and its backing accelerator. > > > > request: > > {"execute" : "query-cpu-model" } > > > > answer: > > {"return" : {"name": "2827-ga2", "accel": "kvm" }} > > > > Alias names are resolved to their respective machine type and GA names > > already during cpu instantiation. Thus, also a cpu model like 'host' > > which is implemented as alias will return its normalized cpu model name. > > > > Furthermore the patch implements the following function: > > > > - s390_cpu_models_used(), returns true if S390 cpu models are in use > > > > Signed-off-by: Michael Mueller > > --- > [...] > > +static inline char *strdup_s390_cpu_name(S390CPUClass *cc) > > +{ > > + return g_strdup_printf("%04x-ga%u", cc->proc.type, cc->mach.ga); > > +} > > How exactly is this information going to be used by clients? If getting > the correct type and ga values is important for them, maybe you could > add them as integer fields, instead of requiring clients to parse the > CPU model name? The consumer don't need to parse the name, it is just important for them to have distinctive names that correlate with the names returned by query-cpu-definitions. Once the name of an active guest is known, e.g. ("2827-ga2", "kvm") a potential migration target can be verified, i.e. its query-cpu-definitions answer for "kvm" has to contain "2827-ga2" with the attribute runnable set to true. With that mechanism also the largest common denominator can be calculated. That model will be used then. I also changed the above mentioned routine to map the cpu model none case: static inline char *strdup_s390_cpu_name(S390CPUClass *cc) { if (cpuid(cc->proc)) { return g_strdup_printf("%04x-ga%u", cc->proc.type, cc->mach.ga); } else { return g_strdup("none"); } } This implicitly will fail a comparison for cpu model ("none", "kvm") as that will never be part of the query-cpu-definitions answer. I actually applied a couple of your suggestions like: - test for NULL skipped after strdup_s390_cpu_name() - strdup_s390_cpu_name() now also handles none cpu model case - omit runnable and is-default field from query-cpu-definitions answer when they are false - global variable cpu_models_used dropped - function s390_cpu_models_used() dropped - routine query-cpu-definitions has a single code path now Only the integration of the ACCEL_ID with the cpu state in cpu_generic_init() and the change for the query-cpus implementation is under construction. I hope to resend the patches by tomorrow evening. Thanks, Michael >