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: Tue, 9 Feb 2016 20:25:32 +0100 Message-ID: <56BA3D2C.4090409@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> <5561EE27.7060005@web.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="U2nGQHjejagO5iSpDewCE3MRJnxBSbtuh" Cc: kvm , Joel Schopp To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Paolo Bonzini Return-path: Received: from mout.web.de ([212.227.17.12]:52534 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932078AbcBITZr (ORCPT ); Tue, 9 Feb 2016 14:25:47 -0500 In-Reply-To: <5561EE27.7060005@web.de> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --U2nGQHjejagO5iSpDewCE3MRJnxBSbtuh Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 2015-05-24 17:28, Jan Kiszka wrote: > 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 emula= ting >>>> 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 = no >>> way for the host to force its PAT value and ignore the guest's. I'm >>> worried about potential performance problems in the guest. >> >> 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 w= e >> somehow optimize cache coherent cases later. >=20 > This topic is still open - and the patch still applies. Just rebased by kvm patch queue for some new entries - in this old one is still there. What can we do about it? Jan --U2nGQHjejagO5iSpDewCE3MRJnxBSbtuh 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 iEYEARECAAYFAla6PSwACgkQitSsb3rl5xThywCgtFAMt/JYFhp2gyccFLc3x3nB pAYAoOgP2j4rS8zuWNo9XWCtzTouGb/E =yQDG -----END PGP SIGNATURE----- --U2nGQHjejagO5iSpDewCE3MRJnxBSbtuh--