From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Han, Huaitong" <huaitong.han@intel.com>
Subject: Re: [V3 PATCH 7/9] x86/hvm: pkeys,
 add pkeys support for guest_walk_tables
Date: Fri, 11 Dec 2015 07:18:28 +0000
Message-ID: <1449818314.3868.37.camel@intel.com>
References: <1449479780-19146-1-git-send-email-huaitong.han@intel.com>
	<1449479780-19146-8-git-send-email-huaitong.han@intel.com>
	<5669CB7F.8080206@citrix.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
In-Reply-To: <5669CB7F.8080206@citrix.com>
Content-Language: en-US
Content-ID: <80B07C00159A7B478F5AA212434A6B2C@intel.com>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: "george.dunlap@eu.citrix.com" <george.dunlap@eu.citrix.com>, "ian.campbell@citrix.com" <ian.campbell@citrix.com>, "Dong, Eddie" <eddie.dong@intel.com>, "andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>, "wei.liu2@citrix.com" <wei.liu2@citrix.com>, "ian.jackson@eu.citrix.com" <ian.jackson@eu.citrix.com>, "Tian, Kevin" <kevin.tian@intel.com>, "stefano.stabellini@eu.citrix.com" <stefano.stabellini@eu.citrix.com>, "jbeulich@suse.com" <jbeulich@suse.com>, "Nakajima, Jun" <jun.nakajima@intel.com>, "keir@xen.org" <keir@xen.org>
Cc: "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
List-Id: xen-devel@lists.xenproject.org

On Thu, 2015-12-10 at 18:59 +0000, Andrew Cooper wrote:
> On 07/12/15 09:16, Huaitong Han wrote:
> > +
> > +    /* PKRU dom0 is always zero */
> > +    if ( likely(!pte_pkeys) )
> > +        return 0;
> 
> This is not an architectural restriction (as far as I can tell).  Xen
> must never make assumptions about how a guest chooses to use a
> feature.
Yes, I will remove the code section.

On my test machine, writing non-zero value to PKRU domain 0 will lead
to a GP fault, this is also conform to the usage scenario, and I will
ask the intel architect the reason why SDM does not describe.

If it is OK, I will send the other patch or new version patch to
improve the efficiency of the code.
> 
> ~Andrew