Re: [Qemu-devel] [PATCH v2 6/6] s390x/pci: Unplug remaining requested devices on pcihost reset

[David Hildenbrand <david@redhat.com>]

On 01.02.19 11:19, Cornelia Huck wrote:
> On Wed, 30 Jan 2019 16:57:33 +0100
> David Hildenbrand <david@redhat.com> 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 <david@redhat.com>
>> ---
>>  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
> 
> I'm afraid this one doesn't quite apply without the first patches in
> the series, and I'm not sure how to fix it up. I'll either take a
> rebase on a codebase without patches 1-3, or this patch together with
> patches 1-3 after they get acks (whatever comes first :)
> 

I guess it's only the comment that get's added in patch #1, so no major
conflicts.

-- 

Thanks,

David / dhildenb