On 01/10/2021 12:45, Gerd Hoffmann wrote:
On Fri, Oct 01, 2021 at 10:25:02AM +0200, 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().
+ /*
+ * pending_deleted_event is used by virtio-net failover to detect the
+ * end of the unplug operation, the flag is set to false in
+ * acpi_pcihp_eject_slot() when the operation is completed.
+ */
+ pdev->qdev.pending_deleted_event = true;
This has the side effect of blocking a second 'device_del' command.
This problem is not introduced by this patch as it only adds the code we already have in
PCIe Native hotplug to ACPI hotplug (but see below).
So, in case the first time didn't work (for example due to the guest not
listening because grub just doesn't do that), you can try a second time
once the linux kernel is up'n'running.
I suspect this patch will break that (didn't actually test though).
I think the solution to this problem is to not check for pending_deleted_event value in
qmp_device_del().
But this has been explicitly added by:
commit cce8944cc9efab47d4bf29cfffb3470371c3541b
Author: Julia Suvorova <jus...@redhat.com>
Date: Thu Feb 20 17:55:56 2020 +0100
qdev-monitor: Forbid repeated device_del
Device unplug can be done asynchronously. Thus, sending the second
device_del before the previous unplug is complete may lead to
unexpected results. On PCIe devices, this cancels the hot-unplug
process.
Signed-off-by: Julia Suvorova <jus...@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
Message-Id: <20200220165556.39388-1-jus...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
So do you mean ACPI differs from PCIe Native hotplug in this case?
Thanks,
Laurent
