habanalabs/gaudi: scrub all memory upon closing FD

habanalabs/gaudi: scrub all memory upon closing FD

In cases of multi-tenants, administrators may want to prevent data
leakage between users running on the same device one after another.

To do that the driver can scrub the internal memory (both SRAM and
DRAM) after a user finish to use the memory.

Because in GAUDI the driver allows only one application to use the
device at a time, it can scrub the memory when user app close FD.

In future devices where we have MMU on the DRAM, we can scrub the DRAM
memory with a finer granularity (page granularity) when the user
allocates the memory.

This feature is not supported in Goya.

To allow users that want to debug their applications, we add a kernel
module parameter to load the driver with this feature disabled.

Signed-off-by: farah kassabri <fkassabri@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>