Patch "libnvdimm, nd_blk: mask off reserved status bits" has been added to the 4.7-stable tree

Patch "libnvdimm, nd_blk: mask off reserved status bits" has been added to the 4.7-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    libnvdimm, nd_blk: mask off reserved status bits

to the 4.7-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     libnvdimm-nd_blk-mask-off-reserved-status-bits.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 68202c9f0ad6e16ee806fbadbc5838d55fe5aa5c Mon Sep 17 00:00:00 2001
From: Ross Zwisler <ross.zwisler@linux.intel.com>
Date: Fri, 29 Jul 2016 14:59:12 -0600
Subject: libnvdimm, nd_blk: mask off reserved status bits

From: Ross Zwisler <ross.zwisler@linux.intel.com>

commit 68202c9f0ad6e16ee806fbadbc5838d55fe5aa5c upstream.

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

    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.

Reviewed-by: Lee, Chun-Yi <jlee@suse.com>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/acpi/nfit.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/acpi/nfit.c
+++ b/drivers/acpi/nfit.c
@@ -1396,11 +1396,12 @@ static u32 read_blk_stat(struct nfit_blk
 {
 	struct nfit_blk_mmio *mmio = &nfit_blk->mmio[DCR];
 	u64 offset = nfit_blk->stat_offset + mmio->size * bw;
+	const u32 STATUS_MASK = 0x80000037;
 
 	if (mmio->num_lines)
 		offset = to_interleave_offset(offset, mmio);
 
-	return readl(mmio->addr.base + offset);
+	return readl(mmio->addr.base + offset) & STATUS_MASK;
 }
 
 static void write_blk_ctl(struct nfit_blk *nfit_blk, unsigned int bw,


Patches currently in stable-queue which might be from ross.zwisler@linux.intel.com are

queue-4.7/libnvdimm-nd_blk-mask-off-reserved-status-bits.patch