vdpa_sim: add support for user VA

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The new "use_va" module parameter (default: true) is used in
vdpa_alloc_device() to inform the vDPA framework that the device
supports VA.

vringh is initialized to use VA only when "use_va" is true and the
user's mm has been bound. So, only when the bus supports user VA
(e.g. vhost-vdpa).

vdpasim_mm_work_fn work is used to serialize the binding to a new
address space when the .bind_mm callback is invoked, and unbinding
when the .unbind_mm callback is invoked.

Call mmget_not_zero()/kthread_use_mm() inside the worker function
to pin the address space only as long as needed, following the
documentation of mmget() in include/linux/sched/mm.h:

  * Never use this function to pin this address space for an
  * unbounded/indefinite amount of time.

Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20230404131734.45943-1-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

...

This commit is contained in:

Stefano Garzarella 2023-04-04 15:17:34 +02:00 • committed by Michael S. Tsirkin

parent d7621c28fc

commit 4bb94d2de2

2 changed files with 90 additions and 8 deletions

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95

drivers/vdpa/vdpa_sim/vdpa_sim.c

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1

drivers/vdpa/vdpa_sim/vdpa_sim.h

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