From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37671) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dIycf-0005jl-Ti for qemu-devel@nongnu.org; Thu, 08 Jun 2017 10:41:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dIycc-0004ka-1C for qemu-devel@nongnu.org; Thu, 08 Jun 2017 10:41:17 -0400 Date: Fri, 9 Jun 2017 00:41:06 +1000 From: David Gibson Message-ID: <20170608144106.GG25805@umbus.fritz.box> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="LiQwW4YX+w4axhAx" Content-Disposition: inline Subject: [Qemu-devel] unplug_request and migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dgilber@redhat.com, quintela@redhat.com Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org --LiQwW4YX+w4axhAx Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Dave & Juan, I'm hoping one of you can answer this. I'm currently grappling with (amongst other things) a pseries machine racing a hot unplug operation with a migrate. There's various issues with what interim state we need, and which bits of it need to be migrated that I'm still investigating. But, there's a more general question that I'm guessing must have already been addressed for x86. For any "soft" unplug device - i.e. using ->unplug_request, rather than ->unplug, giving a device_del command will just ask the guest nicely to release the device, with the completion of the unplug happening only if and when the guest indicates it's ready for the device to go away. AFAICT, the device_del command will return as soon as the request is made, but if the guest is busy, the completion of the hot unplug could take arbitrarily long. So, what happens if there's a migration in between the unplug_request and the guest completing the unplug? How does libvirt (or whatever) know whether to include the device on the destination machine command line? --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --LiQwW4YX+w4axhAx Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJZOWICAAoJEGw4ysog2bOST4oQAIZkz0+xQSLVRPkwG9eiDl1b eKHteKH3c6TFCToEDVQ1nudFcIWv4VKw91+bQhEgSmiw0ezkRjoDxP73sT5n9YcX 1c1vf0X7NKqOPtdAN6LzG5jLVhCX6wdrwVtfnEWwZX42rAUy0/1UbBHA+/n6hy2T jii5R9/OISJ3E4QUK9AqpkWp1RxQAHO9utwJiyCROcOnrONgdFX1idbNfT424Xm1 Rm6ZhM8OxkcUO/CPNBrBlmqoknWu8fsA+KsTIr8A2JARSu4ZgzXEp3E2XFUKM4S+ t230eYCItsuWIHiOE1VPD1QTkV15AjjlwlACISB5xOUvSotvq7USPjTTBQADlRQs mn9Z95khT49WUsFjWJsQWVU55qoJj4j51o4zPsEAaar7gVJHJsVOpJPUmGYKVi9j NUcsBF6RZ+RWoYhgYwaJpMoht2UphJTkTCxlkur29pTFSDlzEh5w0M2SmSeA73au 7d4TUL5juzfRM3XyO2k1VY8TK9liYB7oul67p4Z27CH6DxoiBae8lIiXrFZpL+XW DtL0CglpSHgMeaKxSYNaMFT+/XaC2hkbssRCOlUfq032vP3YsvhJYS4L9fpEw0DR Cv5C/4DjhM+tCRn4Ozc2JBLxQAyMPOiarRadtYUAWy7WQagM51NxLfZoRCnGrqE8 /bmAUVhaptyYzcqjbnFn =zcui -----END PGP SIGNATURE----- --LiQwW4YX+w4axhAx--