[Qemu-devel] [PATCH 00/11] virtio: cleanup and fix hot-unplug

[Paolo Bonzini]

This series fixes hot-unplug of virtio devices, which can crash due to
dangling pointer accesses.

The current implementation supports guest-initiated hot-unplug via the
virtio_bus_destroy_device function, but not hot-unplugging the virtio
device by virtue of unplugging its parent container device.

The problem is that the callback for the bus implementation to cleanup
is placed in the wrong place; it is in virtio_bus_destroy_device, which
should be called by the bus, instead of being somewhere in device code.
We need to have the callback in device code (for example in dc->exit),
so that we invoke it on every unplug action, no matter who starts it.

Thus, the series cleans up plugging and unplugging of virtio devices
so that it does not need any help from the bus (patches 1-4).  It then
stops the virtio devices' overriding of dc->exit, moving their cleanup
code to the new exit callback in VirtioDeviceClass (patches 5-10).
Finally, patch 11 can make virtio-pci implement the device_unplugged
callback.

Something similar is probably needed in virtio-ccw too.  However,
virtio-ccw needs more surgery because it does not include a device_plugged
callback either, so I did not touch it.

Paolo Bonzini (11):
  virtio-bus: remove vdev field
  virtio-pci: remove vdev field
  virtio-ccw: remove vdev field
  virtio-bus: cleanup plug/unplug interface
  virtio-blk: switch exit callback to VirtioDeviceClass
  virtio-serial: switch exit callback to VirtioDeviceClass
  virtio-net: switch exit callback to VirtioDeviceClass
  virtio-scsi: switch exit callback to VirtioDeviceClass
  virtio-balloon: switch exit callback to VirtioDeviceClass
  virtio-rng: switch exit callback to VirtioDeviceClass
  virtio-pci: add device_unplugged callback

 hw/block/virtio-blk.c           |  10 ++--
 hw/char/virtio-serial-bus.c     |  10 ++--
 hw/net/virtio-net.c             |  11 ++--
 hw/s390x/virtio-ccw.c           |  80 +++++++++++++++------------
 hw/s390x/virtio-ccw.h           |   1 -
 hw/scsi/vhost-scsi.c            |  11 ++--
 hw/scsi/virtio-scsi.c           |  15 +++--
 hw/virtio/virtio-balloon.c      |  10 ++--
 hw/virtio/virtio-bus.c          |  81 +++++++++++++++------------
 hw/virtio/virtio-mmio.c         |   9 +--
 hw/virtio/virtio-pci.c          | 119 ++++++++++++++++++++++++----------------
 hw/virtio/virtio-pci.h          |   1 -
 hw/virtio/virtio-rng.c          |  10 ++--
 hw/virtio/virtio.c              |   7 ++-
 include/hw/virtio/virtio-bus.h  |  22 +++++---
 include/hw/virtio/virtio-scsi.h |   2 +-
 include/hw/virtio/virtio.h      |   1 +
 17 files changed, 223 insertions(+), 177 deletions(-)

-- 
1.8.3.1