From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47376) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gaQ4F-0002PM-Ek for qemu-devel@nongnu.org; Fri, 21 Dec 2018 14:02:40 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gaQ4A-0006rQ-D4 for qemu-devel@nongnu.org; Fri, 21 Dec 2018 14:02:39 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47158) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gaQ4A-0006nc-68 for qemu-devel@nongnu.org; Fri, 21 Dec 2018 14:02:34 -0500 Date: Fri, 21 Dec 2018 14:02:28 -0500 From: "Michael S. Tsirkin" Message-ID: <20181221140016-mutt-send-email-mst@kernel.org> References: <20181217141740.16ccfaa1@Igors-MacBook-Pro.local> <20181218092723.yhaerzm4vlzgef65@linux.intel.com> <20181218155536.2b35a037@Igors-MacBook-Pro.local> <20181219025717.6m72hq73p2haexkv@linux.intel.com> <20181219114037.5550a562@redhat.com> <20181220211801.GR19442@habkost.net> <20181221151325.39b64733@redhat.com> <20181221160944.65c5skjhkel3of7y@linux.intel.com> <20181221120320-mutt-send-email-mst@kernel.org> <20181221173758.4ohku43as4dkb355@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181221173758.4ohku43as4dkb355@linux.intel.com> Subject: Re: [Qemu-devel] [PATCH v3 1/2] intel-iommu: differentiate host address width from IOVA address width. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Yu Zhang Cc: Igor Mammedov , Eduardo Habkost , qemu-devel@nongnu.org, Peter Xu , Paolo Bonzini , Richard Henderson On Sat, Dec 22, 2018 at 01:37:58AM +0800, Yu Zhang wrote: > On Fri, Dec 21, 2018 at 12:04:49PM -0500, Michael S. Tsirkin wrote: > > On Sat, Dec 22, 2018 at 12:09:44AM +0800, Yu Zhang wrote: > > > Well, my understanding of the vt-d spec is that the address limitation in > > > DMAR are referring to the same concept of CPUID.MAXPHYSADDR. I do not think > > > there's any different in the native scenario. :) > > > > I think native machines exist on which the two values are different. > > Is that true? > > I think the answer is not. My understanding is that HAW(host address wdith) is > the maximum physical address width a CPU can detects(by cpuid.0x80000008). > > I agree there are some addresses the CPU does not touch, but they are still in > the physical address space, and there's only one physical address space... > > B.R. > Yu Ouch I thought we are talking about the virtual address size. I think I did have a box where VTD's virtual address size was smaller than CPU's. For physical one - we just need to make it as big as max supported memory right? -- MST