Currently libvhost-user is hardcoded to at most 8 virtqueues. The
device backend should decide the number of virtqueues, not
libvhost-user. This is important for multiqueue device backends where
the guest driver needs an accurate number of virtqueues.
This change breaks libvhost-user and libvhost-user-glib API stability.
There is no stability guarantee yet, so make this change now and update
all in-tree library users.
This patch touches up vhost-user-blk, vhost-user-gpu, vhost-user-input,
vhost-user-scsi, and vhost-user-bridge. If the device has a fixed
number of queues that exact number is used. Otherwise the previous
default of 8 virtqueues is used.
vu_init() and vug_init() can now fail if malloc() returns NULL. I
considered aborting with an error in libvhost-user but it should be safe
to instantiate new vhost-user instances at runtime without risk of
terminating the process. Therefore callers need to handle the vu_init()
failure now.
vhost-user-blk and vhost-user-scsi duplicate virtqueue index checks that
are already performed by libvhost-user. This code would need to be
modified to use max_queues but remove it completely instead since it's
redundant.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190626074815.19994-3-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
6f5fd83788