From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: [PATCH 14/19] KVM: PPC: Book3S HV: add a control to make the XIVE EQ pages dirty Date: Tue, 5 Feb 2019 16:30:58 +1100 Message-ID: <20190205053058.GF22661@umbus.fritz.box> References: <20190107184331.8429-1-clg@kaod.org> <20190107184331.8429-15-clg@kaod.org> <20190204051833.GG1927@umbus.fritz.box> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="+jhVVhN62yS6hEJ8" Cc: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, Paul Mackerras , linuxppc-dev@lists.ozlabs.org To: =?iso-8859-1?Q?C=E9dric?= Le Goater Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" List-Id: kvm.vger.kernel.org --+jhVVhN62yS6hEJ8 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Feb 04, 2019 at 04:46:00PM +0100, C=E9dric Le Goater wrote: > On 2/4/19 6:18 AM, David Gibson wrote: > > On Mon, Jan 07, 2019 at 07:43:26PM +0100, C=E9dric Le Goater wrote: > >> When the VM is stopped in a migration sequence, the sources are masked > >> and the XIVE IC is synced to stabilize the EQs. When done, the KVM > >> ioctl KVM_DEV_XIVE_SAVE_EQ_PAGES is called to mark dirty the EQ pages. > >> > >> The migration can then transfer the remaining dirty pages to the > >> destination and start collecting the state of the devices. > >=20 > > Is there a reason to make this a separate step from the SYNC > > operation? >=20 > Hmm, apart from letting QEMU orchestrate the migration step by step, no. >=20 > We could merge the SYNC and the SAVE_EQ_PAGES in a single KVM operation.= =20 > I think that should be fine. I think that makes sense. SYNC is supposed to complete delivery of any in-flight interrupts, and to me writing to the queue page and marking it dirty as a result is a logical part of that. > However, it does not make sense to call this operation without the VM=20 > being stopped. I wonder how this can checked from KVM. May be we > can't. I don't think it matters. qemu is allowed to shoot itself in the foot. --=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 --+jhVVhN62yS6hEJ8 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAlxZH5IACgkQbDjKyiDZ s5JS9BAA30gFIgvUZHxJzKwRH1asbUzKh0BEJ5jDYlBlpoWoOsq3zpPGw8cTr9pd qtNHy2aaMnWGcfhm2LZYbgmW7F3zCgiKXLLoFOSiCQVKNLRp7s3H1tlipA1F/Pgc 4QPD1AHZykA9K1bKjLNXqqCLCJNLWY5HLeCbxSv8noojwADxk8ZZdTv3SJsUw0K/ MygO8hgsDmM7EDj5ud3iFmd9P9nf4q8+z7Z5RfpmkYwyvQGe5t7/3AhOmQR2QAct MKXgwl9goJIgFOoCJXj24cx+jkQXKY3GyVXKclIm3bpO9JJPjxM32LnRcYe88zB6 AtQA9o+FGF9vnhrwsWp4aHarPfdj/0c9A+u3xnDtf7PcoFnd9s9zbQSWNXKrB/ti 2O2iKBGf5I7eMaNyBEUVk7wxe3BQPRFgF57I8akIqdyv5OZOevLTZTgUwGqz+ndb zTdM2FRLDZYeSrNBVkEs0QgFffn4RD435DNYedpofs/PD0sLvLi+om+NWi95u02H aSUHGcCimPYp5x6V+OZS8+zxcC8S9p/3St6YczJdlOiqUWFHrO0Dya1WvAZw2hdk 5LLrwVOqsU3g0Riz96DhdVizQWLzUrOU5NUozBPvc/c8/+SYzvN8xzPVmYijMHeI XrNqY2XdYvUrtVN6So6mQt40//EBZRxYGEUU+BX+ohiOA+7/sJs= =aJ8z -----END PGP SIGNATURE----- --+jhVVhN62yS6hEJ8--