On Mon, 21 Jan 2019 14:42:49 +0100
David Hildenbrand <da...@redhat.com> wrote:
> When resetting the guest we should unplug and remove all devices that
> are still pending. Otherwise the fresh guest will see devices that will
> suddenly vanish.
>
> Can be triggered e.g. via
> (hmp) device_add virtio-mouse-pci,id=test
> (hmp) stop
> (hmp) device_del test
> (hmp) system_reset
> (hmp) c
>
> The device will vanish after roughly 5 minutes. With this patch, the
> device will vanish on reboot (S390_RESET_EXTERNAL and S390_RESET_REIPL,
> which reset the pcihost bridge via qemu_devices_reset()). If we want
> these devices to vanish directly on any reset (S390_RESET_MODIFIED_CLEAR
> and S390_RESET_LOAD_NORMAL), we have to modify s390_machine_reset(). But
> I have the feeling that this should not be done for all reset types.
>
> 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 (same thing could happen right now if the timer expires
> just after reset).
I'm wondering what the architecture says regarding those events -- can
someone with access to the documentation comment?
>
> Signed-off-by: David Hildenbrand <da...@redhat.com>
> ---
> hw/s390x/s390-pci-bus.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
> index bc17a8cf65..b70ae25533 100644
> --- a/hw/s390x/s390-pci-bus.c
> +++ b/hw/s390x/s390-pci-bus.c
> @@ -1102,6 +1102,14 @@ static void s390_pcihost_reset(DeviceState *dev)
> {
> S390pciState *s = S390_PCI_HOST_BRIDGE(dev);
> PCIBus *bus = s->parent_obj.bus;
> + S390PCIBusDevice *pbdev, *next;
> +
> + /* Unplug all pending devices that were requested to be released */
> + QTAILQ_FOREACH_SAFE(pbdev, &s->zpci_devs, link, next) {
> + if (pbdev->release_timer) {
> + s390_pcihost_timer_cb(pbdev);
> + }
> + }
>
> s->bus_no = 0;
> pci_for_each_device(bus, pci_bus_num(bus), s390_pci_enumerate_bridge, s);
