From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55314) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fkEYH-0007Tm-Ju for qemu-devel@nongnu.org; Mon, 30 Jul 2018 16:13:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fkEYC-00010u-KU for qemu-devel@nongnu.org; Mon, 30 Jul 2018 16:13:57 -0400 Date: Mon, 30 Jul 2018 17:13:46 -0300 From: Eduardo Habkost Message-ID: <20180730201346.GL12380@localhost.localdomain> References: <20180725091233.3300-1-david@redhat.com> <20180727145551.2a1df03f.cohuck@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [qemu-s390x] [PATCH v1] s390x/cpu_models: Add "-cpu max" support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Hildenbrand Cc: Cornelia Huck , Thomas Huth , Chris Venteicher , Daniel P =?iso-8859-1?Q?=2E_Berrang=E9?= , Alexander Graf , qemu-devel@nongnu.org, Christian Borntraeger , qemu-s390x@nongnu.org, Collin Walling , Richard Henderson On Mon, Jul 30, 2018 at 11:16:38AM +0200, David Hildenbrand wrote: > On 27.07.2018 14:55, Cornelia Huck wrote: > > On Wed, 25 Jul 2018 11:12:33 +0200 > > David Hildenbrand wrote: > > > >> The "max" CPU model behaves like "-cpu host" when KVM is enabled, and like > >> a CPU with the maximum possible feature set when TCG is enabled. > >> > >> While the "host" model can not be used under TCG ("kvm_required"), the > >> "max" model can and "Enables all features supported by the accelerator in > >> the current host". > >> > >> So we can treat "host" just as a special case of "max" (like x86 does). > >> It differs to the "qemu" CPU model under TCG such that compatibility > >> handling will not be performed and that some experimental CPU features > >> not yet part of the "qemu" model might be indicated. > >> > >> These are right now under TCG (see "qemu_MAX"): > >> - stfle53 > >> - msa5-base > >> - zpci > >> > >> This will result right now in the following warning when starting QEMU TCG > >> with the "max" model: > >> "qemu-system-s390x: warning: 'msa5-base' requires 'kimd-sha-512'." > >> > >> The "qemu" model (used as default in QEMU under TCG) will continue to > >> work without such warnings. The "max" mdel in the current form > >> might be interesting for kvm-unit-tests (where we would e.g. now also > >> test "msa5-base"). > >> > >> The "max" model is neither static nor migration safe (like the "host" > >> model). It is independent of the machine but dependends on the accelerator. > >> It can be used to detect the maximum CPU model also under TCG from upper > >> layers without having to care about CPU model names for CPU model > >> expansion. > >> > >> Signed-off-by: David Hildenbrand > >> --- > >> target/s390x/cpu_models.c | 81 +++++++++++++++++++++++++++------------ > >> 1 file changed, 56 insertions(+), 25 deletions(-) > > > > So, what's the outcome? Can I merge this with the discussed minor > > edits, or should I wait for a v2? > > > > Eduardo identified possible optimizations independent of this patch, so > we should be good to go. @Eduardo, please correct me if I'm wrong! This version still looks good to me, my Reviewed-by line still applies. Thanks! -- Eduardo