[PATCH v5 for-next 0/2] RDMA: Provide an API for drivers to disassociate mmap pages

[Junxian Huang]

Provide an API rdma_user_mmap_disassociate() for drivers to disassociate
mmap pages. Use this API in hns to prevent userspace from ringing doorbell
when HW is reset.

v4 -> v5:
* Remove 'disassociated' from core.
* Remove lockdep in uverbs_user_mmap_disassociate() since we have
  a new disassociation_lock and don't need to hold hw_destroy_rwsem
  in the newly introduced api.
* Use hr_dev->dis_db to prevent new mmaps once the device is reset.

v3 -> v4:
* Add the newly introduced disassociation_lock to ib_uverbs_mmap()
  and rdma_umap_open() to prevent concurrency with
  rdma_user_mmap_disassociate().
* Change the disassociated flag from atomic_t to bool.

v2 -> v3:
* Walk all ufiles of a device in rdma_user_mmap_disassociate() as Jason
  commented, so drivers don't need to maintain their own list of ucontexts.
* Add a disassociation_lock in uverbs_user_mmap_disassociate() as Jason
  commented to avoid racing between different threads.
* Add a disassociated flag indicating whether mmaps have been disabled
  to prevent new mmap after the disassociation.

v1 -> v2:
* Keep uverbs_user_mmap_disassociate() in uverbs_main.c. The new api
  rdma_user_mmap_disassociate() is also moved to this file.
* Add "#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)" to hns's
  rdma_user_mmap_disassociate() call.

Chengchang Tang (2):
  RDMA/core: Provide rdma_user_mmap_disassociate() to disassociate mmap
    pages
  RDMA/hns: Disassociate mmap pages for all uctx when HW is being reset

 drivers/infiniband/core/uverbs.h           |  2 +
 drivers/infiniband/core/uverbs_main.c      | 47 ++++++++++++++++++++--
 drivers/infiniband/hw/hns/hns_roce_hw_v2.c |  9 +++++
 drivers/infiniband/hw/hns/hns_roce_main.c  |  5 +++
 include/rdma/ib_verbs.h                    |  8 ++++
 5 files changed, 67 insertions(+), 4 deletions(-)

--
2.33.0