From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH v2] KVM: SVM: Sync g_pat with guest-written PAT value Date: Sun, 24 May 2015 17:28:39 +0200 Message-ID: <5561EE27.7060005@web.de> References: <552B5128.4010909@siemens.com> <552B6923.3020602@siemens.com> <20150420161401.GB26491@potion.brq.redhat.com> <5535368B.9060408@siemens.com> <55362FFC.1040905@redhat.com> <20150421122148.GA15983@potion.brq.redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="SPEVgEpGsBOCjFAtQtWlkxHVa0fPOrfqM" Cc: kvm , Joel Schopp To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Paolo Bonzini Return-path: Received: from mout.web.de ([212.227.15.3]:49822 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751244AbbEXP2s (ORCPT ); Sun, 24 May 2015 11:28:48 -0400 In-Reply-To: <20150421122148.GA15983@potion.brq.redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --SPEVgEpGsBOCjFAtQtWlkxHVa0fPOrfqM Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 2015-04-21 14:21, Radim Kr=C4=8Dm=C3=A1=C5=99 wrote: > 2015-04-21 13:09+0200, Paolo Bonzini: >> >> >> On 20/04/2015 19:25, Jan Kiszka wrote: >>> When hardware supports the g_pat VMCB field, we can use it for emulat= ing >>> the PAT configuration that the guest configures by writing to the >>> corresponding MSR. >>> >>> Signed-off-by: Jan Kiszka >> >> I'm not sure about this. The problem is that, unlike Intel, AMD has n= o >> way for the host to force its PAT value and ignore the guest's. I'm >> worried about potential performance problems in the guest. >=20 > We already set g_pat to 0x0007040600070406ULL in init_vmcb(). > This patch uses caching that the guest expects, which might improve > performance as well. I think it's a step in right direction even if we= > somehow optimize cache coherent cases later. This topic is still open - and the patch still applies. Jan --SPEVgEpGsBOCjFAtQtWlkxHVa0fPOrfqM Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEARECAAYFAlVh7icACgkQitSsb3rl5xR70QCfVxwF1afaaYk1KoCevgSpS1Xe 71cAoLo9a1OF6bf8M7X1Aj+csvnFOw0r =ngcp -----END PGP SIGNATURE----- --SPEVgEpGsBOCjFAtQtWlkxHVa0fPOrfqM--