From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59695) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XM7cm-0003zY-9H for qemu-devel@nongnu.org; Mon, 25 Aug 2014 23:40:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XM7cc-0007RG-Ih for qemu-devel@nongnu.org; Mon, 25 Aug 2014 23:40:48 -0400 Received: from e23smtp06.au.ibm.com ([202.81.31.148]:60064) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XM7cb-0007Qg-Th for qemu-devel@nongnu.org; Mon, 25 Aug 2014 23:40:38 -0400 Received: from /spool/local by e23smtp06.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 26 Aug 2014 13:40:32 +1000 Message-ID: <53FC01AF.2070404@au1.ibm.com> Date: Tue, 26 Aug 2014 13:40:31 +1000 From: Sam Mendoza-Jonas MIME-Version: 1.0 References: <1408667050-10789-1-git-send-email-sam.mj@au1.ibm.com> <20140826030119.GM9923@voom.redhat.com> In-Reply-To: <20140826030119.GM9923@voom.redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH V5] spapr: Fix stale HTAB during live migration Reply-To: sam.mj@au1.ibm.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: aik@ozlabs.ru, qemu-ppc@nongnu.org, qemu-devel@nongnu.org On 26/08/14 13:01, David Gibson wrote: > On Fri, Aug 22, 2014 at 10:24:10AM +1000, Samuel Mendoza-Jonas wrote: >> If a guest reboots during a running migration, changes to the >> hash page table are not necessarily updated on the destination. >> Opening a new file descriptor to the HTAB forces the migration >> handler to resend the entire table. > > Of course, arguably this is a kernel bug - the htab fd should probably > start re-reporting things if the htab reset ioctl() is called. But I > guess we need a workaround for existing kernels anyway. That's right, but as you say it would be nice to cover existing kernels. > > However, don't we still have the bug for TCG mode? spapr_reset_htab() > just memset()s the whole hashtable in that case, which will actually > clear all the dirty bits, whereas we need to set them. > True! I'll add a case for this, it should just be a matter of checking & setting htab_first_pass. -- Regards, Sam Mendoza-Jonas ----------- LTC Ozlabs IBM