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

[Ani Sinha]

On Wed, Dec 8, 2021 at 1:20 PM Thomas Huth <thuth@redhat.com> wrote:
>
> 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

Yes I pointed this out in the other thread. Michael was not CC'd there
somehow ...

>
> so we should be fine :-)
>
>   Thomas
>