tree d8827b2e2acab5c8803282db4bbee5c3808ca399
parent 4c3e257b5e6ccba6bd34f780fab8008e0d79680a
author Changpeng Liu <changpeng.liu@intel.com> 1515030812 +0800
committer Michael S. Tsirkin <mst@redhat.com> 1516305157 +0200

vhost-user-blk: introduce a new vhost-user-blk host device

This commit introduces a new vhost-user device for block, it uses a
chardev to connect with the backend, same with Qemu virito-blk device,
Guest OS still uses the virtio-blk frontend driver.

To use it, start QEMU with command line like this:

qemu-system-x86_64 \
    -chardev socket,id=char0,path=/path/vhost.socket \
    -device vhost-user-blk-pci,chardev=char0,num-queues=2, \
            bootindex=2... \

Users can use different parameters for `num-queues` and `bootindex`.

Different with exist Qemu virtio-blk host device, it makes more easy
for users to implement their own I/O processing logic, such as all
user space I/O stack against hardware block device. It uses the new
vhost messages(VHOST_USER_GET_CONFIG) to get block virtio config
information from backend process.

Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>