From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47557) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X9Zd1-0003SV-Ur for qemu-devel@nongnu.org; Tue, 22 Jul 2014 08:57:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X9Zcu-0000t3-Bf for qemu-devel@nongnu.org; Tue, 22 Jul 2014 08:57:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34095) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X9Zcu-0000sc-3W for qemu-devel@nongnu.org; Tue, 22 Jul 2014 08:57:04 -0400 From: Juan Quintela In-Reply-To: <1405955204-10438-1-git-send-email-pbonzini@redhat.com> (Paolo Bonzini's message of "Mon, 21 Jul 2014 17:06:44 +0200") References: <1405955204-10438-1-git-send-email-pbonzini@redhat.com> Date: Tue, 22 Jul 2014 14:56:57 +0200 Message-ID: <87a981y2jq.fsf@troll.troll> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH for-2.1] exec: fix migration with devices that use address_space_rw Reply-To: quintela@redhat.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: peter.maydell@linaro.org, mst@redhat.com, qemu-devel@nongnu.org, dgilbert@redhat.com, kraxel@redhat.com Paolo Bonzini wrote: > Devices that use address_space_rw to write large areas to memory > (as opposed to address_space_map/unmap) were broken with respect > to migration since fe680d0 (exec: Limit translation limiting in > address_space_translate to xen, 2014-05-07). Such devices include > IDE CD-ROMs. > > The reason is that invalidate_and_set_dirty (called by address_space_rw > but not address_space_map/unmap) was only setting the dirty bit for > the first page in the translation. > > To fix this, introduce cpu_physical_memory_set_dirty_range_nocode that > is the same as cpu_physical_memory_set_dirty_range except it does not > muck with the DIRTY_MEMORY_CODE bitmap. This function can be used if > the caller invalidates translations with tb_invalidate_phys_page_range. > > There is another difference between cpu_physical_memory_set_dirty_range > and cpu_physical_memory_set_dirty_flag; the former includes a call > to xen_modified_memory. This is handled separately in > invalidate_and_set_dirty, and is not needed in other callers of > cpu_physical_memory_set_dirty_range_nocode, so leave it alone. > > Just one nit: now that invalidate_and_set_dirty takes care of handling > multiple pages, there is no need for address_space_unmap to wrap it > in a loop. In fact that loop would now be O(n^2). > > Reported-by: Dave Gilbert > Signed-off-by: Paolo Bonzini Reviewed-by: Juan Quintela Paolo, are you doing the pull for this, or should I do it? Thanks, Juan.