iommufd: Do not map/unmap revoked DMABUFs

Once a DMABUF is revoked the domain will be unmapped under the pages
mutex. Double unmapping will trigger a WARN, and mapping while revoked
will fail.

Check for revoked DMABUFs along all the map and unmap paths to resolve
this. Ensure that map/unmap is always done under the pages mutex so it is
synchronized with the revoke notifier.

If a revoke happens between allocating the iopt_pages and the population
to a domain then the population will succeed, and leave things unmapped as
though revoke had happened immediately after.

Currently there is no way to repopulate the domains. Userspace is expected
to know if it is going to do something that would trigger revoke (eg if it
is about to do a FLR) then it should go and remove the DMABUF mappings
before and put the back after. The revoke is only to protect the kernel
from mis-behaving userspace.

Link: https://patch.msgid.link/r/3-v2-b2c110338e3f+5c2-iommufd_dmabuf_jgg@nvidia.com
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Shuai Xue <xueshuai@linux.alibaba.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

0 files changed, 0 insertions, 0 deletions