On Mon, Aug 8, 2016 at 12:10 PM, Ross Zwisler
[off-list ref] wrote:

On Tue, Aug 02, 2016 at 12:26:53PM -0600, Ross Zwisler wrote:

quoted

The "NVDIMM Block Window Driver Writer's Guide":

http://pmem.io/documents/
http://pmem.io/documents/NVDIMM_DriverWritersGuide-July-2016.pdf

defines the layout of the block window status register.  For the July 2016
version of the spec linked to above, this happens in Figure 4 on page 26.

The only bits defined in this spec are bits 31, 5, 4, 2, 1 and 0.  The rest
of the bits in the status register are reserved, and there is a warning
following the diagram that says:

  Note: The driver cannot assume the value of the RESERVED bits in the
  status register are zero. These reserved bits need to be masked off, and
  the driver must avoid checking the state of those bits.

This change ensures that for hardware implementations that set these
reserved bits in the status register, the driver won't incorrectly fail the
block I/Os.

Signed-off-by: Ross Zwisler <redacted>
Reviewed-by: Lee, Chun-Yi <jlee@suse.com>
Cc: Dan Williams <redacted>
Cc: stable@vger.kernel.org # v4.2+

Ping on this patch - through which tree should we merge this for v4.8-rc2?
Dan's nvdimm tree?

It's getting 0-day coverage on my libnvdimm-pending branch and will go
to Linus at the end of the week.