RE: [PATCH v4 3/5] iommufd: Add replace support in iommufd_access_set_ioas()

From: Nicolin Chen nicolinc@nvidia.com Sent: Wednesday, March 8, 2023 10:26 PM

Support an access->ioas replacement in iommufd_access_set_ioas(), which sets the access->ioas to NULL provisionally so that any further incoming iommufd_access_pin_pages() callback can be blocked.

Then, call access->ops->unmap() to clean up the entire iopt. To allow an iommufd_access_unpin_pages() callback to happen via this unmap() call, add an ioas_unpin pointer so the unpin routine won't be affected by the "access->ioas = NULL" trick above.

Suggested-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Nicolin Chen nicolinc@nvidia.com

Reviewed-by: Kevin Tian kevin.tian@intel.com