From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45184) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cVDHU-0004Kt-Iv for qemu-devel@nongnu.org; Sun, 22 Jan 2017 03:13:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cVDHP-00032k-I8 for qemu-devel@nongnu.org; Sun, 22 Jan 2017 03:13:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41336) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cVDHP-00032V-Cg for qemu-devel@nongnu.org; Sun, 22 Jan 2017 03:13:39 -0500 References: <1484917736-32056-1-git-send-email-peterx@redhat.com> <1484917736-32056-20-git-send-email-peterx@redhat.com> From: Jason Wang Message-ID: Date: Sun, 22 Jan 2017 16:13:32 +0800 MIME-Version: 1.0 In-Reply-To: <1484917736-32056-20-git-send-email-peterx@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH RFC v4 19/20] intel_iommu: unmap existing pages before replay List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu , qemu-devel@nongnu.org Cc: tianyu.lan@intel.com, kevin.tian@intel.com, mst@redhat.com, jan.kiszka@siemens.com, alex.williamson@redhat.com, bd.aviv@gmail.com On 2017=E5=B9=B401=E6=9C=8820=E6=97=A5 21:08, Peter Xu wrote: > Previous replay works for domain switch only if the original domain doe= s > not have mapped pages. For example, if we switch domain from A to B, it > will only work if A has no existing mapping. If there is, then there's > problem - current replay didn't make sure the old mappings are cleared > before replaying the new one. I'm not quite sure this is needed. I thought the only thing we need to=20 do is stop DMA of device during the moving? Or is there an example that=20 will cause trouble? Thanks