On Mon, Feb 04, 2019 at 04:46:00PM +0100, Cédric Le Goater wrote: > On 2/4/19 6:18 AM, David Gibson wrote: > > On Mon, Jan 07, 2019 at 07:43:26PM +0100, Cédric 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. > > > > Is there a reason to make this a separate step from the SYNC > > operation? > > Hmm, apart from letting QEMU orchestrate the migration step by step, no. > > We could merge the SYNC and the SAVE_EQ_PAGES in a single KVM operation. > 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
> 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.
--
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
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