Re: [PATCH v5 3/4] failover: fix unplug pending detection

[Thomas Huth]

On 08/12/2021 08.36, Michael S. Tsirkin wrote:
> On Fri, Nov 19, 2021 at 10:07:17AM +0100, Laurent Vivier wrote:
> > Failover needs to detect the end of the PCI unplug to start migration
> > after the VFIO card has been unplugged.
> >
> > To do that, a flag is set in pcie_cap_slot_unplug_request_cb() and reset in
> > pcie_unplug_device().
> >
> > But since
> >      17858a169508 ("hw/acpi/ich9: Set ACPI PCI hot-plug as default on Q35")
> > we have switched to ACPI unplug and these functions are not called anymore
> > and the flag not set. So failover migration is not able to detect if card
> > is really unplugged and acts as it's done as soon as it's started. So it
> > doesn't wait the end of the unplug to start the migration. We don't see any
> > problem when we test that because ACPI unplug is faster than PCIe native
> > hotplug and when the migration really starts the unplug operation is
> > already done.
> >
> > See c000a9bd06ea ("pci: mark device having guest unplug request pending")
> >      a99c4da9fc2a ("pci: mark devices partially unplugged")
> >
> > Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> > Reviewed-by: Ani Sinha <ani@anisinha.ca>
>
> Hmm.  I think this one may be needed for this release actually.
> Isolate from testing changes and repost?

You merged it already here:

 https://gitlab.com/qemu-project/qemu/-/commit/9323f892b39d133eb6

so we should be fine :-)

 Thomas