vdpa_sim: disable page faults around vringh_need_notify_iotlb()

When vdpa_sim runs with use_va (the default), its rings live in user
memory, and vringh reads the ring's flags and event index with
__get_user() through the user address.  The net and block simulators
call vringh_need_notify_iotlb() with bottom halves disabled, so those
reads happen in atomic context.

That only works today because __get_user() has no might_fault() check: a
fault is not handled in atomic context and simply comes back as -EFAULT.
Make that explicit with pagefault_disable() around the call, so vringh
can use the normal user accessors without complaint.  Only the
notification check needs this: the rest of the ring processing runs in
the same kthread without bottom halves disabled, and can fault normally.

Tested-and-acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions