drm/xe/uapi: disallow bind queue sharing

drm/xe/uapi: disallow bind queue sharing

Currently this is very broken if someone attempts to create a bind
queue and share it across multiple VMs. For example currently we assume
it is safe to acquire the user VM lock to protect some of the bind queue
state, but if allow sharing the bind queue with multiple VMs then this
quickly breaks down.

To fix this reject using a bind queue with any VM that is not the same
VM that was originally passed when creating the bind queue. This a uAPI
change, however this was more of an oversight on kernel side that we
didn't reject this, and expectation is that userspace shouldn't be using
bind queues in this way, so in theory this change should go unnoticed.

Based on a patch from Matt Brost.

v2 (Matt B):
  - Hold the vm lock over queue create, to ensure it can't be closed as
    we attach the user_vm to the queue.
  - Make sure we actually check for NULL user_vm in destruction path.
v3:
  - Fix error path handling.

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Reported-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Michal Mrozek <michal.mrozek@intel.com>
Cc: Carl Zhang <carl.zhang@intel.com>
Cc: <stable@vger.kernel.org> # v6.8+
Acked-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Arvind Yadav <arvind.yadav@intel.com>
Acked-by: Michal Mrozek <michal.mrozek@intel.com>
Link: https://patch.msgid.link/20260120110609.77958-3-matthew.auld@intel.com