Merge remote-tracking branch 'mst/tags/for_anthony' into staging

Merge remote-tracking branch 'mst/tags/for_anthony' into staging

pci,virtio

This further optimizes MSIX handling in virtio-pci.
Also included is pci cleanup by Paolo, and pci device
assignment fix by Alex.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
* mst/tags/for_anthony:
  pci-assign: Enable MSIX on device to match guest
  pci: use constants for devices under the 1B36 device ID, document them
  ivshmem: use symbolic constant for PCI ID, add to pci-ids.txt
  virtio-9p: use symbolic constant, add to pci-ids.txt
  reorganize pci-ids.txt
  docs: move pci-ids.txt to docs/specs/
  vhost: backend masking support
  vhost: set started flag while start is in progress
  virtio-net: set/clear vhost_started in reverse order
  virtio: backend virtqueue notifier masking
  virtio-pci: cache msix messages
  kvm: add stub for update msi route
  msix: add api to access msix message
  virtio: don't waste irqfds on control vqs