From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Roedel, Joerg" Subject: Re: [PATCH] KVM: SVM: Keep intercepting task switching with NPT enabled Date: Tue, 1 Nov 2011 17:15:37 +0100 Message-ID: <20111101161537.GI13244@amd.com> References: <4E9DA7EF.30804@siemens.com> <20111018163516.GO2198@amd.com> <4E9DB95C.1030105@redhat.com> <20111101111335.GD13244@amd.com> <4EAFF6A5.8050308@web.de> <20111101153019.GH13244@amd.com> <4EB01516.2070402@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Avi Kivity , Marcelo Tosatti , kvm , Gleb Natapov To: Jan Kiszka Return-path: Received: from ch1ehsobe003.messaging.microsoft.com ([216.32.181.183]:46037 "EHLO ch1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752926Ab1KAQPp (ORCPT ); Tue, 1 Nov 2011 12:15:45 -0400 Content-Disposition: inline In-Reply-To: <4EB01516.2070402@web.de> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Nov 01, 2011 at 11:49:42AM -0400, Jan Kiszka wrote: > On 2011-11-01 16:30, Roedel, Joerg wrote: > > On Tue, Nov 01, 2011 at 09:39:49AM -0400, Jan Kiszka wrote: > >>> So SVM does not guarantee that an intercept during a task-switch can be > >>> restarted. > >> > >> Not a bug but still a deficit as it makes hardware-assisted task > >> switching practically useless, no? > > > > Not entirely. For hypervisors that can guarantee that there will be no > > intercept (NPT pre-mapped, no exceptions intercepted) it will still > > work. > > Yes, but that only covers the niche of simple static ones (partitioning > hypervisors). No, also a hypervisor that creates the nested page-page on advance falls into this category. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632