From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53483) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eFMr2-0004qi-8j for qemu-devel@nongnu.org; Thu, 16 Nov 2017 11:17:29 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eFMqw-0008U4-NH for qemu-devel@nongnu.org; Thu, 16 Nov 2017 11:17:28 -0500 Date: Thu, 16 Nov 2017 18:17:16 +0200 From: "Michael S. Tsirkin" Message-ID: <20171116181556-mutt-send-email-mst@kernel.org> References: <20171116132339.4facb858@bahia.lab.toulouse-stg.fr.ibm.com> <20171116172602-mutt-send-email-mst@kernel.org> <20171116085345.7b02ecdd@t450s.home> <20171116175713-mutt-send-email-mst@kernel.org> <20171116090448.4d53ac71@t450s.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171116090448.4d53ac71@t450s.home> Subject: Re: [Qemu-devel] QEMU terminates during reboot after memory unplug with vhost=on List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson Cc: Greg Kurz , imammedo@redhat.com, bharata@linux.vnet.ibm.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, david@gibson.dropbear.id.au On Thu, Nov 16, 2017 at 09:04:48AM -0700, Alex Williamson wrote: > > Range is unmapped by listener but device has not been reset yet, > > so it will get errors when attempting to access guest RAM. > > So IOMMU faults would occur if the device continues to try to DMA > into that range. Sloppy ordering, but vfio wouldn't have any way to > tell the difference between this and a runtime RAM unplug. It's clear vfio won't be able to tell the difference, but the device will as RAM unplug involves guest coordinating with the device to avoid addressing the removed memory. -- MST