From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52674) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dGWD4-0003r4-Au for qemu-devel@nongnu.org; Thu, 01 Jun 2017 15:56:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dGWD1-0006rv-9A for qemu-devel@nongnu.org; Thu, 01 Jun 2017 15:56:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60848) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dGWD1-0006rk-0H for qemu-devel@nongnu.org; Thu, 01 Jun 2017 15:56:39 -0400 References: <20170531220129.27724-1-aurelien@aurel32.net> <20170531220129.27724-31-aurelien@aurel32.net> <20170601191702.feantajorjt33lsc@aurel32.net> From: David Hildenbrand Message-ID: <42f7b144-4576-33e9-b385-e95e1432d93d@redhat.com> Date: Thu, 1 Jun 2017 21:56:34 +0200 MIME-Version: 1.0 In-Reply-To: <20170601191702.feantajorjt33lsc@aurel32.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 30/30] target/s390x: update maximum TCG model to z800 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Aurelien Jarno Cc: qemu-devel@nongnu.org, Alexander Graf , Richard Henderson On 01.06.2017 21:17, Aurelien Jarno wrote: > On 2017-06-01 10:38, David Hildenbrand wrote: >> On 01.06.2017 00:01, Aurelien Jarno wrote: >>> At the same time fix the TCG version of get_max_cpu_model to return the >>> maximum model like on KVM. Remove the ETF2 and long-displacement >> >> I don't understand the part >> "fix the TCG version of get_max_cpu_model to return the maximum model >> like on KVM". >> >> Can you elaborate? > > Currently get_max_cpu_model returns the features of the base model, so > for example the one of a z900 even on a z800. This makes impossible to > enable the features that are provided by a z800 like etf2 or ldisp. > Right, you can always change the max_cpu_model, e.g. bumping up the version or adding new features, that is just fine. > For what I understand from the KVM code (but I haven't tested), the > function return all the features that are supported by the current CPU, > not all the features that are supported by the base model of the current > CPU. Correct, for KVM it is the detected model, that means: Base features + optional features. > > >>> facilities from the additional features as it is included in the z800. >>> >>> Signed-off-by: Aurelien Jarno >>> --- >>> target/s390x/cpu_models.c | 13 ++++++------- >>> 1 file changed, 6 insertions(+), 7 deletions(-) >>> >>> diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c >>> index fc3cb25cc3..c13bbd852c 100644 >>> --- a/target/s390x/cpu_models.c >>> +++ b/target/s390x/cpu_models.c >>> @@ -668,8 +668,6 @@ static void add_qemu_cpu_model_features(S390FeatBitmap fbm) >>> static const int feats[] = { >>> S390_FEAT_STFLE, >>> S390_FEAT_EXTENDED_IMMEDIATE, >>> - S390_FEAT_EXTENDED_TRANSLATION_2, >>> - S390_FEAT_LONG_DISPLACEMENT, >>> S390_FEAT_LONG_DISPLACEMENT_FAST, >>> S390_FEAT_ETF2_ENH, >>> S390_FEAT_STORE_CLOCK_FAST, >>> @@ -696,9 +694,9 @@ static S390CPUModel *get_max_cpu_model(Error **errp) >>> if (kvm_enabled()) { >>> kvm_s390_get_host_cpu_model(&max_model, errp); >>> } else { >>> - /* TCG emulates a z900 (with some optional additional features) */ >>> - max_model.def = &s390_cpu_defs[0]; >>> - bitmap_copy(max_model.features, max_model.def->default_feat, >>> + /* TCG emulates a z800 (with some optional additional features) */ >>> + max_model.def = s390_find_cpu_def(0x2066, 7, 3, NULL); >>> + bitmap_copy(max_model.features, max_model.def->full_feat, >>> S390_FEAT_MAX); >>> add_qemu_cpu_model_features(max_model.features); >>> } >>> @@ -956,8 +954,9 @@ static void s390_qemu_cpu_model_initfn(Object *obj) >>> S390CPU *cpu = S390_CPU(obj); >>> >>> cpu->model = g_malloc0(sizeof(*cpu->model)); >>> - /* TCG emulates a z900 (with some optional additional features) */ >>> - memcpy(&s390_qemu_cpu_defs, &s390_cpu_defs[0], sizeof(s390_qemu_cpu_defs)); >>> + /* TCG emulates a z800 (with some optional additional features) */ >>> + memcpy(&s390_qemu_cpu_defs, s390_find_cpu_def(0x2066, 7, 3, NULL), >>> + sizeof(s390_qemu_cpu_defs)); >> >> No changing the qemu model without compatibility handling. > > This patch series is based on the patch from Thomas Huth. It means the > QEMU model is still based on a z900, but that it is possible to enable > some more features like etf2. Thomas' code did neither change features nor the "model definition". It just allows for some more feature to be set. It is a hack. I am pretty sure that expanding the "qemu" CPU model now (QMP query-cpu-model-expansion) will indicate a z800, not a z900. See cpu_info_from_model(). And that is a problem, because the QEMU CPU model is a "migration-safe" CPU model, meaning it must remain equal for every compatibility machine. Thanks. > > Aurelien > -- Thanks, David