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c29dd73f74
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>
117 lines
3.6 KiB
C
117 lines
3.6 KiB
C
/*
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* Abstract virtio based memory device
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*
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* Copyright (C) 2023 Red Hat, Inc.
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*
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* Authors:
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* David Hildenbrand <david@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2.
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* See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "hw/virtio/virtio-md-pci.h"
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#include "hw/mem/memory-device.h"
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#include "qapi/error.h"
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#include "qemu/error-report.h"
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void virtio_md_pci_pre_plug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
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{
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DeviceState *dev = DEVICE(vmd);
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HotplugHandler *bus_handler = qdev_get_bus_hotplug_handler(dev);
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MemoryDeviceState *md = MEMORY_DEVICE(vmd);
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Error *local_err = NULL;
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if (!bus_handler && dev->hotplugged) {
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/*
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* Without a bus hotplug handler, we cannot control the plug/unplug
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* order. We should never reach this point when hotplugging on x86,
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* however, better add a safety net.
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*/
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error_setg(errp, "hotplug of virtio based memory devices not supported"
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" on this bus.");
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return;
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}
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/*
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* First, see if we can plug this memory device at all. If that
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* succeeds, branch of to the actual hotplug handler.
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*/
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memory_device_pre_plug(md, ms, NULL, &local_err);
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if (!local_err && bus_handler) {
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hotplug_handler_pre_plug(bus_handler, dev, &local_err);
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}
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error_propagate(errp, local_err);
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}
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void virtio_md_pci_plug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
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{
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DeviceState *dev = DEVICE(vmd);
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HotplugHandler *bus_handler = qdev_get_bus_hotplug_handler(dev);
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MemoryDeviceState *md = MEMORY_DEVICE(vmd);
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Error *local_err = NULL;
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/*
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* Plug the memory device first and then branch off to the actual
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* hotplug handler. If that one fails, we can easily undo the memory
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* device bits.
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*/
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memory_device_plug(md, ms);
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if (bus_handler) {
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hotplug_handler_plug(bus_handler, dev, &local_err);
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if (local_err) {
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memory_device_unplug(md, ms);
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}
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}
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error_propagate(errp, local_err);
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}
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void virtio_md_pci_unplug_request(VirtIOMDPCI *vmd, MachineState *ms,
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Error **errp)
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{
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/* We don't support hot unplug of virtio based memory devices */
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error_setg(errp, "virtio based memory devices cannot be unplugged.");
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}
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void virtio_md_pci_unplug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
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{
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DeviceState *dev = DEVICE(vmd);
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HotplugHandler *bus_handler = qdev_get_bus_hotplug_handler(dev);
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MemoryDeviceState *md = MEMORY_DEVICE(vmd);
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Error *local_err = NULL;
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/* Unplug the memory device while it is still realized. */
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memory_device_unplug(md, ms);
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if (bus_handler) {
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hotplug_handler_unplug(bus_handler, dev, &local_err);
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if (local_err) {
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/* Not expected to fail ... but still try to recover. */
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memory_device_plug(md, ms);
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error_propagate(errp, local_err);
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return;
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}
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} else {
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/* Very unexpected, but let's just try to do the right thing. */
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warn_report("Unexpected unplug of virtio based memory device");
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qdev_unrealize(dev);
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}
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}
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static const TypeInfo virtio_md_pci_info = {
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.name = TYPE_VIRTIO_MD_PCI,
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.parent = TYPE_VIRTIO_PCI,
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.instance_size = sizeof(VirtIOMDPCI),
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.class_size = sizeof(VirtIOMDPCIClass),
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.abstract = true,
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.interfaces = (InterfaceInfo[]) {
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{ TYPE_MEMORY_DEVICE },
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{ }
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},
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};
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static void virtio_md_pci_register(void)
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{
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type_register_static(&virtio_md_pci_info);
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}
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type_init(virtio_md_pci_register)
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