[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH v2 6/6] s390x/pci: Unplug remaining requested de

From: Collin Walling
Subject: Re: [Qemu-devel] [PATCH v2 6/6] s390x/pci: Unplug remaining requested devices on pcihost reset
Date: Thu, 31 Jan 2019 15:26:30 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1

On 1/30/19 10:57 AM, David Hildenbrand wrote:
When resetting the guest we should unplug and remove all devices that
are still pending.

With this patch, the requested device will be unpluged on reboot
(S390_RESET_EXTERNAL and S390_RESET_REIPL, which reset the pcihost bridge
via qemu_devices_reset()).

This approach is similar to what's done for acpi PCI hotplug in
acpi_pcihp_reset() -> acpi_pcihp_update() ->
acpi_pcihp_update_hotplug_bus() -> acpi_pcihp_eject_slot().

s390_pci_generate_plug_event()'s will still be generated, I guess this
is not an issue. The same thing would happen right now when unplugging
a device just before starting the guest.

Signed-off-by: David Hildenbrand <address@hidden>
  hw/s390x/s390-pci-bus.c | 15 +++++++++++++++
  1 file changed, 15 insertions(+)

diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
index 867801ccf9..b9b0f44087 100644
--- a/hw/s390x/s390-pci-bus.c
+++ b/hw/s390x/s390-pci-bus.c
@@ -1092,6 +1092,21 @@ static void s390_pcihost_reset(DeviceState *dev)
      S390pciState *s = S390_PCI_HOST_BRIDGE(dev);
      PCIBus *bus = s->parent_obj.bus;
+    S390PCIBusDevice *pbdev, *next;
+    /* Process all pending unplug requests */
+    QTAILQ_FOREACH_SAFE(pbdev, &s->zpci_devs, link, next) {
+        if (pbdev->unplug_requested) {
+            if (pbdev->summary_ind) {
+                pci_dereg_irqs(pbdev);
+            }
+            if (pbdev->iommu->enabled) {
+                pci_dereg_ioat(pbdev->iommu);
+            }
+            pbdev->state = ZPCI_FS_STANDBY;
+            s390_pci_perform_unplug(pbdev);
+        }
+    }
       * When resetting a PCI bridge, the assigned numbers are set to 0. So

Just "talking out loud" to reaffirm my understanding:

The ..._unplug_request function will have already generated the
deconfigure unplug event, and the unplug_requested flag will be set.
Makes sense -- easy to follow. :)

The callback that this code is essentially replacing used to generate a
CONFIGURED_TO_STBRES plug event, but as I recall from a previous
conversation regarding PCI states, we can skip this event because we're
removing the device from the guest during a reset here (there are a few
reasons why we'd do this, but no sense in listing them here). Also makes
sense to me.

Reviewed-by: Collin Walling <address@hidden>

reply via email to

[Prev in Thread] Current Thread [Next in Thread]