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virtio-md-pci: Handle unplug of virtio based memory devices

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While we fence unplug requests from the outside, the VM can still
trigger unplug of virtio based memory devices, for example, in Linux
doing on a virtio-mem-pci device:
    # echo 0 > /sys/bus/pci/slots/3/power

While doing that is not really expected to work without harming the
guest OS (e.g., removing a virtio-mem device while it still provides
memory), let's make sure that we properly handle it on the QEMU side.

We'll add support for unplugging of virtio-mem devices in some
configurations next.

Message-ID: <20230711153445.514112-5-david@redhat.com>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
This commit is contained in:
David Hildenbrand 2023-07-11 17:34:42 +02:00
parent 30ec5ccd3a
commit c29dd73f74
1 changed files with 22 additions and 1 deletions
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23
hw/virtio/virtio-md-pci.c
View file

@ -14,6 +14,7 @@
#include "hw/virtio/virtio-md-pci.h"
#include "hw/mem/memory-device.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
void virtio_md_pci_pre_plug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
{
@ -74,7 +75,27 @@ void virtio_md_pci_unplug_request(VirtIOMDPCI *vmd, MachineState *ms,
void virtio_md_pci_unplug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
{
/* We don't support hot unplug of virtio based memory devices */
DeviceState *dev = DEVICE(vmd);
HotplugHandler *bus_handler = qdev_get_bus_hotplug_handler(dev);
MemoryDeviceState *md = MEMORY_DEVICE(vmd);
Error *local_err = NULL;
/* Unplug the memory device while it is still realized. */
memory_device_unplug(md, ms);
if (bus_handler) {
hotplug_handler_unplug(bus_handler, dev, &local_err);
if (local_err) {
/* Not expected to fail ... but still try to recover. */
memory_device_plug(md, ms);
error_propagate(errp, local_err);
return;
}
} else {
/* Very unexpected, but let's just try to do the right thing. */
warn_report("Unexpected unplug of virtio based memory device");
qdev_unrealize(dev);
}
}
static const TypeInfo virtio_md_pci_info = {