From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39205) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W5dcI-0002Sv-Nk for qemu-devel@nongnu.org; Tue, 21 Jan 2014 10:52:01 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1W5dc9-0005ES-FZ for qemu-devel@nongnu.org; Tue, 21 Jan 2014 10:51:54 -0500 Received: from cantor2.suse.de ([195.135.220.15]:58804 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W5dc9-0005EM-9M for qemu-devel@nongnu.org; Tue, 21 Jan 2014 10:51:45 -0500 Message-ID: <52DE978E.3020309@suse.de> Date: Tue, 21 Jan 2014 16:51:42 +0100 From: =?ISO-8859-15?Q?Andreas_F=E4rber?= MIME-Version: 1.0 References: <1390228618-21663-1-git-send-email-ehabkost@redhat.com> <52DD9F77.4040904@suse.de> <52DE45E3.5010208@redhat.com> In-Reply-To: <52DE45E3.5010208@redhat.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] target-i386: enable x2apic by default on more recent CPU models List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Eduardo Habkost , "Michael S. Tsirkin" , qemu-devel@nongnu.org, Bandan Das , Anthony Liguori , Igor Mammedov Am 21.01.2014 11:03, schrieb Paolo Bonzini: > Il 20/01/2014 23:13, Andreas F=E4rber ha scritto: >> I don't like the argument that we can put arbitrary stuff in our model >> definitions and rely on TCG not having implemented it to make it >> correct. Is x2apic something that TCG can never implement for some >> reason? Then that needs a better explanation. Otherwise, is there no >> criteria we can add this flag for when kvm_enabled()? >=20 > We already do that for other bits (e.g. XSAVE/OSXSAVE), Please point me to the commit, a search for xsave did not come up with a commit changing such a thing - either it did not go through my queue or it slipped me through: Bugs are no excuse to produce more bugs. > and in fact it > is the same that we do for KVM: the KVM_GET_SUPPORTED_CPUID result is > used to trim the generic feature bits. Our model definitions are the place to put stuff that real CPUs have. Either the CPU has it or it doesn't. If it does, then this patch is fully correct and it's TCG's job to mask things out. If we're adding artificial flags to the generic model definitions just to make KVM faster, then it is wrong - we have a choice of post_initialize and realize hooks for that. Andreas --=20 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imend=F6rffer; HRB 16746 AG N=FCrnbe= rg