From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40590) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fj2Hs-0005VY-0Z for qemu-devel@nongnu.org; Fri, 27 Jul 2018 08:56:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fj2Hm-000840-VT for qemu-devel@nongnu.org; Fri, 27 Jul 2018 08:56:03 -0400 Date: Fri, 27 Jul 2018 14:55:51 +0200 From: Cornelia Huck Message-ID: <20180727145551.2a1df03f.cohuck@redhat.com> In-Reply-To: <20180725091233.3300-1-david@redhat.com> References: <20180725091233.3300-1-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [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: qemu-s390x@nongnu.org, qemu-devel@nongnu.org, Richard Henderson , Alexander Graf , Christian Borntraeger , Thomas Huth , Chris Venteicher , Collin Walling , "Daniel P . =?UTF-8?B?QmVycmFuZ8Op?=" , Eduardo Habkost 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?