[Qemu-devel] [PATCH 0/5] Support more virtio queues

[Jason Wang]

We current limit the max virtio queues to 64. This is not sufficient
to support some multiqueue deivces (e.g recent Linux support up to 256
tap queues). So this series try to let virtio to support more queues.

No much works needs to be done except:

- Patch 1 renames VIRTIO_PCI_QUEUE_MAX to a more generic name:
  VIRTIO_QUEUE_MAX
- Patch 2 simply increase the the limitation to 513 (256 queue pairs)
- Patch 3 fixes a bug in virtio_del_queue()
- Patch 4 tries to remove the hard coded MSI-X bar size (4096) and allow up to
  2048 MSI-X entries.
- Patch 5 add a boolean property to let the virtio-net can calculate
  the MSI-X bar size based on the number of MSI-X vectors and keep
  migration compability with legacy version whose bar size is 4096.

With this patch, we can support up to 256 queues.Since x86 can only
allow about 240 interrupt vectors for MSI-X, current Linux driver can
only have about 80 queue pairs has their private MSI-X interrupt
vectors. With sharing IRQ with queue pairs (RFC posted in
https://lkml.org/lkml/2014/12/25/169), Linux driver can have up
to about 186 queue pairs has their private MSI-X interrupt vectors.

Thanks

Jason Wang (5):
  virtio: rename VIRTIO_PCI_QUEUE_MAX to VIRTIO_QUEUE_MAX
  virtio: increase VIRITO_QUEUE_MAX to 513
  virtio-net: fix the upper bound when trying to delete queues
  pci: remove hard-coded bar size in msix_init_exclusive_bar()
  virtio-pci: introduce auto_msix_bar_size property

 hw/block/nvme.c              |  2 +-
 hw/char/virtio-serial-bus.c  |  2 +-
 hw/i386/pc_piix.c            |  4 ++++
 hw/i386/pc_q35.c             |  4 ++++
 hw/misc/ivshmem.c            |  2 +-
 hw/net/virtio-net.c          |  2 +-
 hw/pci/msix.c                | 18 +++++++-----------
 hw/ppc/spapr.c               |  5 +++++
 hw/s390x/s390-virtio-bus.c   |  4 ++--
 hw/s390x/s390-virtio-ccw.c   |  2 +-
 hw/s390x/virtio-ccw.c        | 10 +++++-----
 hw/scsi/virtio-scsi.c        |  4 ++--
 hw/virtio/virtio-mmio.c      |  4 ++--
 hw/virtio/virtio-pci.c       | 27 ++++++++++++++++++++-------
 hw/virtio/virtio-pci.h       |  3 +++
 hw/virtio/virtio.c           | 26 +++++++++++++-------------
 include/hw/compat.h          |  8 ++++++++
 include/hw/pci/msix.h        |  2 +-
 include/hw/s390x/s390_flic.h |  2 +-
 include/hw/virtio/virtio.h   |  2 +-
 20 files changed, 83 insertions(+), 50 deletions(-)

-- 
1.9.1