From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Deegan Subject: Re: [PATCH v8 2/4] x86/hvm: Treat non-instruction fetch nested page faults also as read violations Date: Thu, 28 Aug 2014 12:13:44 +0200 Message-ID: <20140828101344.GD60905@deinos.phlegethon.org> References: <1408455621-4069-2-git-send-email-tamas.lengyel@zentific.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1408455621-4069-2-git-send-email-tamas.lengyel@zentific.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Tamas K Lengyel Cc: kevin.tian@intel.com, keir@xen.org, suravee.suthikulpanit@amd.com, jun.nakajima@intel.com, eddie.dong@intel.com, xen-devel@lists.xen.org, Aravind.Gopalakrishnan@amd.com, JBeulich@suse.com, boris.ostrovsky@oracle.com List-Id: xen-devel@lists.xenproject.org At 15:40 +0200 on 19 Aug (1408459219), Tamas K Lengyel wrote: > As pointed out by Jan Beulich in http://lists.xen.org/archives/html/xen-devel/2014-08/msg01269.html: "Read-modify-write instructions absolutely need to be treated as read accesses, yet hardware doesn't guarantee to tell us so (they may surface as just write accesses)." This patch addresses the issue in both the VMX and the SVM side. > > VMX: Treat all write data access violations also as read violations (in addition to those that were already reported as read violations). > SVM: Refine the meaning of read data access violations to distinguish between read/write and instruction fetch access violations. > > With this patch both VMX and SVM specific nested page fault handling code reports violations the same way, thus abstracting the hardware specific behaviour from the layers above. > > Suggested-by: Jan Beulich > Signed-off-by: Tamas K Lengyel > Reviewed-by: Boris Ostrovsky Reviewed-by: Tim Deegan