From: "Roedel, Joerg" <Joerg.Roedel@amd.com>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] KVM: SVM: Add xsetbv intercept
Date: Mon, 6 Dec 2010 18:48:52 +0100 [thread overview]
Message-ID: <20101206174852.GG4936@amd.com> (raw)
In-Reply-To: <4CFD0B06.9010308@redhat.com>
On Mon, Dec 06, 2010 at 11:10:46AM -0500, Avi Kivity wrote:
> On 12/03/2010 06:42 PM, Joerg Roedel wrote:
> > This patch implements the xsetbv intercept to the AMD part
> > of KVM. This makes AVX usable in a save way for the guest on
> > AVX capable AMD hardware.
> > The patch is tested by using AVX in the guest and host in
> > parallel and checking for data corruption. I also used the
> > KVM xsave unit-tests and they all pass.
> >
>
> That is really strange. You didn't need to do anything to get cpuid.avx
> recognized. So running an older kvm on newer hardware will happily
> expose avx even though it's not supported.
>
> We screwed up - we should have made cpuid.avx dependent on vendor support.
Hmm, right. The set_supported_cpuid arch-callback should basically
disable xsave on AMD for all KVM versions which do not handle the xsetbv
intercept.
Joerg
--
AMD Operating System Research Center
Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
General Managers: Alberto Bozzo, Andrew Bowd
Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632
next prev parent reply other threads:[~2010-12-06 17:48 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-03 16:42 [PATCH] KVM: SVM: Add xsetbv intercept Joerg Roedel
2010-12-06 16:10 ` Avi Kivity
2010-12-06 17:48 ` Roedel, Joerg [this message]
2010-12-07 9:34 ` Avi Kivity
2010-12-07 16:12 ` Roedel, Joerg
2010-12-07 16:15 ` [PATCH 1/2] KVM: SVM: Do not report xsave in supported cpuid Joerg Roedel
2010-12-07 16:15 ` [PATCH 2/2] KVM: SVM: Add xsetbv intercept Joerg Roedel
2010-12-08 10:35 ` Avi Kivity
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