[PATCH RFC PKS/PMEM 57/58] nvdimm/pmem: Stray access protection for pmem->virt_addr

[ira.weiny@xxxxxxxxx]

From: Ira Weiny <ira.weiny@xxxxxxxxx>

The pmem driver uses a cached virtual address to access its memory
directly.  Because the nvdimm driver is well aware of the special
protections it has mapped memory with, we call dev_access_[en|dis]able()
around the direct pmem->virt_addr (pmem_addr) usage instead of the
unnecessary overhead of trying to get a page to kmap.

Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
---
 drivers/nvdimm/pmem.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index fab29b514372..e4dc1ae990fc 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -148,7 +148,9 @@ static blk_status_t pmem_do_read(struct pmem_device *pmem,
        if (unlikely(is_bad_pmem(&pmem->bb, sector, len)))
                return BLK_STS_IOERR;
 
+       dev_access_enable(false);
        rc = read_pmem(page, page_off, pmem_addr, len);
+       dev_access_disable(false);
        flush_dcache_page(page);
        return rc;
 }
@@ -180,11 +182,13 @@ static blk_status_t pmem_do_write(struct pmem_device 
*pmem,
         * after clear poison.
         */
        flush_dcache_page(page);
+       dev_access_enable(false);
        write_pmem(pmem_addr, page, page_off, len);
        if (unlikely(bad_pmem)) {
                rc = pmem_clear_poison(pmem, pmem_off, len);
                write_pmem(pmem_addr, page, page_off, len);
        }
+       dev_access_disable(false);
 
        return rc;
 }
-- 
2.28.0.rc0.12.gb6a658bd00c9