Merge branch 'libnvdimm-for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull nvdimm mcsafe_memcpy use from Dan Williams:
 "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 compilation problems from the initial posting have been fixed,
  this has appeared in a -next release with no reported issues, and it
  picked up an ack from Ingo.  There is no pressing need to merge this
  in 4.6- rc2.  However, if we wait until 4.7 the new memcpy_mcsafe()
  capability will ship without a user in 4.6-final"

* 'libnvdimm-for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  x86, pmem: use memcpy_mcsafe() for memcpy_from_pmem()

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
  *

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();

include/linux/pmem.h

@@ -42,6 +42,13 @@ 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)
+{
+	BUG();
+	return -EFAULT;
+}
+
 static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
 		struct iov_iter *i)
 {
@@ -66,14 +73,17 @@ 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)