dmaengine: idxd: Make read buffer sysfs attributes invisible for Intel IAA

mainline inclusion
from mainline-v6.2
commit 9a8ddb35
category: bugfix
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I596WO
CVE: NA

Intel-SIG: commit 9a8ddb35 dmaengine: idxd: Make read buffer sysfs attributes invisible for Intel IAA.
Incremental backporting patches for DSA/IAA on Intel Xeon platform.

--------------------------------

In current code, the following sysfs attributes are exposed to user to
show or update the values:
  max_read_buffers (max_tokens)
  read_buffer_limit (token_limit)
  group/read_buffers_allowed (group/tokens_allowed)
  group/read_buffers_reserved (group/tokens_reserved)
  group/use_read_buffer_limit (group/use_token_limit)

>From Intel IAA spec [1], Intel IAA does not support Read Buffer
allocation control. So these sysfs attributes should not be supported on
IAA device.

Fix this issue by making these sysfs attributes invisible through
is_visible() filter when the device is IAA.

Add description in the ABI documentation to mention that these
attributes are not visible when the device does not support Read Buffer
allocation control.

[1]: https://cdrdv2.intel.com/v1/dl/getContent/721858



Fixes: fde212e4 ("dmaengine: idxd: deprecate token sysfs attributes for read buffers")
Fixes: c52ca478 ("dmaengine: idxd: add configuration component of driver")
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20221022074949.11719-1-xiaochen.shen@intel.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>