From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MJWak-0006t5-N4 for qemu-devel@nongnu.org; Wed, 24 Jun 2009 13:49:02 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MJWaf-0006mG-M1 for qemu-devel@nongnu.org; Wed, 24 Jun 2009 13:49:02 -0400 Received: from [199.232.76.173] (port=39165 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MJWaf-0006lj-5F for qemu-devel@nongnu.org; Wed, 24 Jun 2009 13:48:57 -0400 Received: from mail-ew0-f211.google.com ([209.85.219.211]:51316) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MJWae-0002Oy-Id for qemu-devel@nongnu.org; Wed, 24 Jun 2009 13:48:56 -0400 Received: by ewy7 with SMTP id 7so1328502ewy.34 for ; Wed, 24 Jun 2009 10:48:55 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20090624172934.GG14121@shareable.org> References: <20090623162140.GB4379@random.random> <20090624172934.GG14121@shareable.org> Date: Wed, 24 Jun 2009 19:48:55 +0200 Message-ID: <5b31733c0906241048m2bb9cb72wdc3d8c0e316611f3@mail.gmail.com> Subject: Re: [Qemu-devel] allow sysenter on 32bit guests running on vmx host From: Filip Navara Content-Type: multipart/alternative; boundary=0016365ee0ba99ce6c046d1bb81a List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jamie Lokier Cc: Andrea Arcangeli , qemu-devel@nongnu.org --0016365ee0ba99ce6c046d1bb81a Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit On Wed, Jun 24, 2009 at 7:29 PM, Jamie Lokier wrote: [snip] > > > Fix is to set model = 3 so it'll be the duron cpu when kvm runs on > > amd bare metal (not anymore athlon but userland doesn't see the > > difference) and it'll be PII that has sysenter functional like all > > cpus that run KVM have too when on intel bare metal. > > But the vendor id is AMD not Intel in this structure, and the PPro > workaround is Intel-only. > > I've checked Linux kernel code, and it only disables the sep feature > if the vendor is GenuineIntel, on old and current kernels. > > So your patch should make no difference to Linux guests. Did you > check Linux behaviour? Does Windows ignore the vendor id? No, it doesn't ignore the vendor, at least not on NT 5.2 (Windows Server 2003) and newer kernels. I'm pretty sure it wasn't ignored even in Windows XP, older systems didn't implement it. Best regards, Filip Navara --0016365ee0ba99ce6c046d1bb81a Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
On Wed, Jun 24, 2009 at 7:29 PM, Jamie Lokier <jamie@shareable.= org> wrote:
[snip]=A0
> Fix is to set model =3D 3 so it'll be the duron cpu when kvm runs = on
> amd bare metal (not anymore athlon but userland doesn't see the > difference) and it'll be PII that has sysenter functional like all=
> cpus that run KVM have too when on intel bare metal.

But the vendor id is AMD not Intel in this structure, and the PPro workaround is Intel-only.

I've checked Linux kernel code, and it only disables the sep feature if the vendor is GenuineIntel, on old and current kernels.

So your patch should make no difference to Linux guests. =A0Did you
check Linux behaviour? =A0Does Windows ignore the vendor id?
No, it doesn't ignore the vendor, at least not on NT = 5.2 (Windows Server 2003) and newer kernels. I'm pretty sure it wasn= 9;t ignored even in Windows XP, older systems didn't implement it.

Best regards,
Filip Navara
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