[Qemu-devel] [PATCH 00/15] qdev: make reset semantics more clear and consistent, reset qbuses under virtio devices

[Paolo Bonzini <pbonzini@redhat.com>]

After discussion with mst on the topic of resetting virtio devices,
here is a series that hopefully clarifies the semantics of bus and
device resets.

After this series, there are two kinds of resets:

1) device-level reset is the kind of reset that you get with a register
write on the device.  It will clear interrupts and DMAs among other things,
but not any bus-level state, for example it will not clear PCI BARs and
other configuration space data.  It is done with qdev_reset_all.

2) bus-level reset is the kind of reset that you get with a register
write on the device that exports the bus (including triggering a device-level
reset on the device that exports the bus).  It will do a device-level
reset on the child, but also clear bus-level state such as PCI BARs and
other configuration space data.  It can be triggered for all devices
on a bus with qbus_reset_all.  There is still no API for a bus-level
reset of a single device (like PCI FLR), this can be added later.

Patches 1-5 are miscellaneous fixes to the reset paths.

Patches 6-8 introduce qbus_reset_all and uses it.

Patches 9-12 switch qdev_reset_all and qbus_reset_all from pre-order
to post-order, and document the resulting semantics.

Finally, patches 13-15 adjust the virtio implementations to use qdev
device-level reset more extensively.

Paolo Bonzini (15):
  qdev: do not reset a device until the parent has been initialized
  intel-hda: do not reset codecs from intel_hda_reset
  pci: clean up resetting of IRQs
  virtio-pci: reset device before PCI layer
  virtio-s390: add a reset function to virtio-s390 devices
  qdev: add qbus_reset_all
  pci: do not export pci_bus_reset
  lsi: use qbus_reset_all to reset SCSI bus
  qdev: allow both pre- and post-order vists in qdev walking functions
  qdev: switch reset to post-order
  qdev: remove device_reset
  qdev: document reset semantics
  virtio-pci: reset all qbuses too when writing to the status field
  virtio-s390: reset all qbuses too when writing to the status field
  virtio-serial: do not perform bus reset by hand

 hw/intel-hda.c         |  1 -
 hw/lsi53c895a.c        |  7 +----
 hw/pci.c               | 16 ++++------
 hw/pci.h               |  1 -
 hw/pci_bridge.c        |  2 +-
 hw/qdev-core.h         | 83 ++++++++++++++++++++++++++++++++++++++++++--------
 hw/qdev.c              | 70 +++++++++++++++++++++++++++---------------
 hw/s390-virtio-bus.c   | 16 +++++++++-
 hw/virtio-pci.c        | 27 +++++++---------
 hw/virtio-serial-bus.c | 19 +++---------
 10 files changed, 156 insertions(+), 86 deletions(-)

-- 
1.8.0.2