From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=AN0r=4C=vger.kernel.org=kvm-owner@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
X-Spam-Level: 
X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no
	autolearn_force=no version=3.4.0
Received: from mail.kernel.org (mail.kernel.org [198.145.29.99])
	by smtp.lore.kernel.org (Postfix) with ESMTP id 8EDDBC35242
	for <kvm@archiver.kernel.org>; Fri, 14 Feb 2020 22:04:44 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [209.132.180.67])
	by mail.kernel.org (Postfix) with ESMTP id 681232082F
	for <kvm@archiver.kernel.org>; Fri, 14 Feb 2020 22:04:44 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1727589AbgBNWEM (ORCPT <rfc822;kvm@archiver.kernel.org>);
        Fri, 14 Feb 2020 17:04:12 -0500
Received: from mga11.intel.com ([192.55.52.93]:7992 "EHLO mga11.intel.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1726079AbgBNWDm (ORCPT <rfc822;kvm@vger.kernel.org>);
        Fri, 14 Feb 2020 17:03:42 -0500
X-Amp-Result: UNKNOWN
X-Amp-Original-Verdict: FILE UNKNOWN
X-Amp-File-Uploaded: False
Received: from fmsmga004.fm.intel.com ([10.253.24.48])
  by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Feb 2020 14:03:42 -0800
X-ExtLoop1: 1
X-IronPort-AV: E=Sophos;i="5.70,442,1574150400"; 
   d="scan'208";a="257662235"
Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202])
  by fmsmga004.fm.intel.com with ESMTP; 14 Feb 2020 14:03:41 -0800
Date:   Fri, 14 Feb 2020 14:03:41 -0800
From:   Sean Christopherson <sean.j.christopherson@intel.com>
To:     Jim Mattson <jmattson@google.com>
Cc:     Chia-I Wu <olvaffe@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>,
        kvm list <kvm@vger.kernel.org>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Joerg Roedel <joro@8bytes.org>,
        Gurchetan Singh <gurchetansingh@chromium.org>,
        Gerd Hoffmann <kraxel@redhat.com>,
        ML dri-devel <dri-devel@lists.freedesktop.org>
Subject: Re: [RFC PATCH 0/3] KVM: x86: honor guest memory type
Message-ID: <20200214220341.GJ20690@linux.intel.com>
References: <20200213213036.207625-1-olvaffe@gmail.com>
 <8fdb85ea-6441-9519-ae35-eaf91ffe8741@redhat.com>
 <CAPaKu7T8VYXTMc1_GOzJnwBaZSG214qNoqRr8c7Z4Lb3B7dtTg@mail.gmail.com>
 <b82cd76c-0690-c13b-cf2c-75d7911c5c61@redhat.com>
 <20200214195229.GF20690@linux.intel.com>
 <CAPaKu7Q4gehyhEgG_Nw=tiZiTh+7A8-uuXq1w4he6knp6NWErQ@mail.gmail.com>
 <CALMp9eRwTxdqxAcobZ7sYbD=F8Kga=jR3kaz-OEYdA9fV0AoKQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CALMp9eRwTxdqxAcobZ7sYbD=F8Kga=jR3kaz-OEYdA9fV0AoKQ@mail.gmail.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: kvm-owner@vger.kernel.org
Precedence: bulk
List-ID: <kvm.vger.kernel.org>
X-Mailing-List: kvm@vger.kernel.org

On Fri, Feb 14, 2020 at 01:56:48PM -0800, Jim Mattson wrote:
> On Fri, Feb 14, 2020 at 1:47 PM Chia-I Wu <olvaffe@gmail.com> wrote:
> > AFAICT, it is currently allowed on ARM (verified) and AMD (not
> > verified, but svm_get_mt_mask returns 0 which supposedly means the NPT
> > does not restrict what the guest PAT can do).  This diff would do the
> > trick for Intel without needing any uapi change:
> 
> I would be concerned about Intel CPU errata such as SKX40 and SKX59.

The part KVM cares about, #MC, is already addressed by forcing UC for MMIO.
The data corruption issue is on the guest kernel to correctly use WC
and/or non-temporal writes.