[GIT PULL] libnvdimm, pmem: hook up memcpy_mcsafe

["Williams, Dan J" <dan.j.williams@intel.com>]

Hi Linus, please pull from:

  git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm libnvdimm-for-next

Now that mcsafe_memcpy() has landed, and the return value was been
clarified in commit cbf8b5a2b649 "x86/mm, x86/mce: Fix return
type/value for memcpy_mcsafe()", let's hook up its primary usage in the
pmem driver.

---

The following changes since commit d88f48e12821ab4b2244124d50ac094568f48db5:

  Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (2016-03-24 09:47:32 -0700)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm libnvdimm-for-next

for you to fetch changes up to a2b056ea291d321a8addb34bf30a656b99cf70b1:

  x86, pmem: use memcpy_mcsafe() for memcpy_from_pmem() (2016-03-25 09:16:56 -0700)

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

commit a2b056ea291d321a8addb34bf30a656b99cf70b1
Author: Dan Williams <dan.j.williams@intel.com>
Date:   Tue Mar 8 10:30:19 2016 -0800

    x86, pmem: use memcpy_mcsafe() for memcpy_from_pmem()
    
    Update the definition of memcpy_from_pmem() to return 0 or a negative
    error code.  Implement x86/arch_memcpy_from_pmem() with memcpy_mcsafe().
    
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
    Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/x86/include/asm/pmem.h |  9 +++++++++
 drivers/nvdimm/pmem.c       |  4 ++--
 include/linux/pmem.h        | 15 +++++++++------
 3 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/pmem.h b/arch/x86/include/asm/pmem.h
index bf8b35d2035a..fbc5e92e1ecc 100644
--- a/arch/x86/include/asm/pmem.h
+++ b/arch/x86/include/asm/pmem.h
@@ -47,6 +47,15 @@ static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
 		BUG();
 }
 
+static inline int arch_memcpy_from_pmem(void *dst, const void __pmem *src,
+		size_t n)
+{
+	if (static_cpu_has(X86_FEATURE_MCE_RECOVERY))
+		return memcpy_mcsafe(dst, (void __force *) src, n);
+	memcpy(dst, (void __force *) src, n);
+	return 0;
+}
+
 /**
  * arch_wmb_pmem - synchronize writes to persistent memory
  *
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index ca5721c306bb..cc31c6f1f88e 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -99,7 +99,7 @@ static int pmem_do_bvec(struct pmem_device *pmem, struct page *page,
 		if (unlikely(bad_pmem))
 			rc = -EIO;
 		else {
-			memcpy_from_pmem(mem + off, pmem_addr, len);
+			rc = memcpy_from_pmem(mem + off, pmem_addr, len);
 			flush_dcache_page(page);
 		}
 	} else {
@@ -295,7 +295,7 @@ static int pmem_rw_bytes(struct nd_namespace_common *ndns,
 
 		if (unlikely(is_bad_pmem(&pmem->bb, offset / 512, sz_align)))
 			return -EIO;
-		memcpy_from_pmem(buf, pmem->virt_addr + offset, size);
+		return memcpy_from_pmem(buf, pmem->virt_addr + offset, size);
 	} else {
 		memcpy_to_pmem(pmem->virt_addr + offset, buf, size);
 		wmb_pmem();
diff --git a/include/linux/pmem.h b/include/linux/pmem.h
index 3ec5309e29f3..cdb024386f3a 100644
--- a/include/linux/pmem.h
+++ b/include/linux/pmem.h
@@ -66,14 +66,17 @@ static inline void arch_invalidate_pmem(void __pmem *addr, size_t size)
 #endif
 
 /*
- * Architectures that define ARCH_HAS_PMEM_API must provide
- * implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(),
- * arch_copy_from_iter_pmem(), arch_clear_pmem(), arch_wb_cache_pmem()
- * and arch_has_wmb_pmem().
+ * memcpy_from_pmem - read from persistent memory with error handling
+ * @dst: destination buffer
+ * @src: source buffer
+ * @size: transfer length
+ *
+ * Returns 0 on success negative error code on failure.
  */
-static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size)
+static inline int memcpy_from_pmem(void *dst, void __pmem const *src,
+		size_t size)
 {
-	memcpy(dst, (void __force const *) src, size);
+	return arch_memcpy_from_pmem(dst, src, size);
 }
 
 static inline bool arch_has_pmem_api(void)