From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34958) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dzLfz-0003n8-UC for qemu-devel@nongnu.org; Tue, 03 Oct 2017 07:47:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dzLfw-0007x8-Ph for qemu-devel@nongnu.org; Tue, 03 Oct 2017 07:47:51 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:56749) by eggs.gnu.org with esmtps (TLS1.0:RSA_ARCFOUR_SHA1:16) (Exim 4.71) (envelope-from ) id 1dzLfw-0007uk-JO for qemu-devel@nongnu.org; Tue, 03 Oct 2017 07:47:48 -0400 Date: Tue, 3 Oct 2017 12:47:43 +0100 From: Anthony PERARD Message-ID: <20171003114742.GC2116@perard.uk.xensource.com> References: <20171002163058.15651-1-anthony.perard@citrix.com> <20171003113337.nkde7v236fww3npt@MacBook-Pro-de-Roger.local> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20171003113337.nkde7v236fww3npt@MacBook-Pro-de-Roger.local> Subject: Re: [Qemu-devel] [Xen-devel] [PATCH] migration, xen: Fix block image lock issue on live migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Roger Pau =?iso-8859-1?Q?Monn=E9?= Cc: qemu-devel@nongnu.org, Wei Liu , Juan Quintela , Ian Jackson , "Dr. David Alan Gilbert" , xen-devel@lists.xenproject.org On Tue, Oct 03, 2017 at 12:33:37PM +0100, Roger Pau Monné wrote: > On Mon, Oct 02, 2017 at 04:30:58PM +0000, Anthony PERARD wrote: > > When doing a live migration of a Xen guest with libxl, the images for > > block devices are locked by the original QEMU process, and this prevent > > the QEMU at the destination to take the lock and the migration fail. > > > > From QEMU point of view, once the RAM of a domain is migrated, there is > > two QMP commands, "stop" then "xen-save-devices-state", at which point a > > new QEMU is spawned at the destination. > > > > Release locks in "xen-save-devices-state" so the destination can takes > > them. > > What happens if the migration fails on the destination? Will QEMU pick > the lock again when resuming on the source in this case? Yes, calling the QMP command "cont" to resume the activity makes QEMU take the lock again, and libxl would call "cont". (I don't think you can pick this kind of lock ;-). ) -- Anthony PERARD From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony PERARD Subject: Re: [PATCH] migration, xen: Fix block image lock issue on live migration Date: Tue, 3 Oct 2017 12:47:43 +0100 Message-ID: <20171003114742.GC2116@perard.uk.xensource.com> References: <20171002163058.15651-1-anthony.perard@citrix.com> <20171003113337.nkde7v236fww3npt@MacBook-Pro-de-Roger.local> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dzLfv-0002GM-Ee for xen-devel@lists.xenproject.org; Tue, 03 Oct 2017 11:47:47 +0000 Content-Disposition: inline In-Reply-To: <20171003113337.nkde7v236fww3npt@MacBook-Pro-de-Roger.local> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Roger Pau =?iso-8859-1?Q?Monn=E9?= Cc: Wei Liu , Juan Quintela , Ian Jackson , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , xen-devel@lists.xenproject.org List-Id: xen-devel@lists.xenproject.org T24gVHVlLCBPY3QgMDMsIDIwMTcgYXQgMTI6MzM6MzdQTSArMDEwMCwgUm9nZXIgUGF1IE1vbm7D qSB3cm90ZToKPiBPbiBNb24sIE9jdCAwMiwgMjAxNyBhdCAwNDozMDo1OFBNICswMDAwLCBBbnRo b255IFBFUkFSRCB3cm90ZToKPiA+IFdoZW4gZG9pbmcgYSBsaXZlIG1pZ3JhdGlvbiBvZiBhIFhl biBndWVzdCB3aXRoIGxpYnhsLCB0aGUgaW1hZ2VzIGZvcgo+ID4gYmxvY2sgZGV2aWNlcyBhcmUg bG9ja2VkIGJ5IHRoZSBvcmlnaW5hbCBRRU1VIHByb2Nlc3MsIGFuZCB0aGlzIHByZXZlbnQKPiA+ IHRoZSBRRU1VIGF0IHRoZSBkZXN0aW5hdGlvbiB0byB0YWtlIHRoZSBsb2NrIGFuZCB0aGUgbWln cmF0aW9uIGZhaWwuCj4gPiAKPiA+IEZyb20gUUVNVSBwb2ludCBvZiB2aWV3LCBvbmNlIHRoZSBS QU0gb2YgYSBkb21haW4gaXMgbWlncmF0ZWQsIHRoZXJlIGlzCj4gPiB0d28gUU1QIGNvbW1hbmRz LCAic3RvcCIgdGhlbiAieGVuLXNhdmUtZGV2aWNlcy1zdGF0ZSIsIGF0IHdoaWNoIHBvaW50IGEK PiA+IG5ldyBRRU1VIGlzIHNwYXduZWQgYXQgdGhlIGRlc3RpbmF0aW9uLgo+ID4gCj4gPiBSZWxl YXNlIGxvY2tzIGluICJ4ZW4tc2F2ZS1kZXZpY2VzLXN0YXRlIiBzbyB0aGUgZGVzdGluYXRpb24g Y2FuIHRha2VzCj4gPiB0aGVtLgo+IAo+IFdoYXQgaGFwcGVucyBpZiB0aGUgbWlncmF0aW9uIGZh aWxzIG9uIHRoZSBkZXN0aW5hdGlvbj8gV2lsbCBRRU1VIHBpY2sKPiB0aGUgbG9jayBhZ2FpbiB3 aGVuIHJlc3VtaW5nIG9uIHRoZSBzb3VyY2UgaW4gdGhpcyBjYXNlPwoKWWVzLCBjYWxsaW5nIHRo ZSBRTVAgY29tbWFuZCAiY29udCIgdG8gcmVzdW1lIHRoZSBhY3Rpdml0eSBtYWtlcyBRRU1VCnRh a2UgdGhlIGxvY2sgYWdhaW4sIGFuZCBsaWJ4bCB3b3VsZCBjYWxsICJjb250Ii4gKEkgZG9uJ3Qg dGhpbmsgeW91IGNhbgpwaWNrIHRoaXMga2luZCBvZiBsb2NrIDstKS4gKQoKLS0gCkFudGhvbnkg UEVSQVJECgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpY ZW4tZGV2ZWwgbWFpbGluZyBsaXN0Clhlbi1kZXZlbEBsaXN0cy54ZW4ub3JnCmh0dHBzOi8vbGlz dHMueGVuLm9yZy94ZW4tZGV2ZWwK