[PATCH] acpi: pcihp: make pending delete expire in 5sec

[Igor Mammedov <imammedo@redhat.com>]

with Q35 using ACPI PCI hotplug by default, user's request to unplug
device is ignored when it's issued before guest OS has been booted.
And any additional attempt to request device hot-unplug afterwards
results in following error:

  "Device XYZ is already in the process of unplug"

arguably it can be considered as a regression introduced by [2],
before which it was possible to issue unplug request multiple
times.

Allowing pending delete expire brings ACPI PCI hotplug on par
with native PCIe unplug behavior [1] which in its turn refers
back to ACPI PCI hotplug ability to repeat unplug requests.

PS:
From ACPI point of view, unplug request sets PCI hotplug status
bit in GPE0 block. However depending on OSPM, status bits may
be retained (Windows) or cleared (Linux) during guest's ACPI
subsystem initialization, and as result Linux guest looses
plug/unplug event (no SCI generated) if plug/unplug has
happend before guest OS initialized GPE registers handling.
I couldn't find any restrictions wrt OPM clearing GPE status
bits ACPI spec.
Hence a fallback approach is to let user repeat unplug request
later at the time when guest OS has booted.

1) 18416c62e3 ("pcie: expire pending delete")
2)
Fixes: cce8944cc9ef ("qdev-monitor: Forbid repeated device_del")
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
CC: mst@redhat.com
CC: anisinha@redhat.com
CC: jusual@redhat.com
CC: kraxel@redhat.com
---
 hw/acpi/pcihp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
index dcfb779a7a..cd4f9fee0a 100644
--- a/hw/acpi/pcihp.c
+++ b/hw/acpi/pcihp.c
@@ -357,6 +357,8 @@ void acpi_pcihp_device_unplug_request_cb(HotplugHandler *hotplug_dev,
      * acpi_pcihp_eject_slot() when the operation is completed.
      */
     pdev->qdev.pending_deleted_event = true;
+    pdev->qdev.pending_deleted_expires_ms =
+        qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 5000; /* 5 secs */
     s->acpi_pcihp_pci_status[bsel].down |= (1U << slot);
     acpi_send_event(DEVICE(hotplug_dev), ACPI_PCI_HOTPLUG_STATUS);
 }
-- 
2.39.1