libnvdimm, pmem: hook up memcpy_mcsafe

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 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.

---
The following changes since commit f55532a0c0b8bb6148f4e07853b876ef73bc69ca:

  Linux 4.6-rc1 (2016-03-26 16:03:24 -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 fc0c2028135c7f75fce36b90e44efb8003a9173b:

  x86, pmem: use memcpy_mcsafe() for memcpy_from_pmem() (2016-03-28 17:19:31 -0700)

----------------------------------------------------------------
Dan Williams (1):
      x86, pmem: use memcpy_mcsafe() for memcpy_from_pmem()

commit fc0c2028135c7f75fce36b90e44efb8003a9173b
Author: Dan Williams <[email protected]>
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().

---
 arch/x86/include/asm/pmem.h |  9 +-+-+-+-+-+-+-+-+- drivers/nvdimm/pmem.c       |  4 +-+--- include/linux/pmem.h        | 22 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------

 3 files changed, 27 insertions(+-), 8 deletions(-)

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 *

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();

index 3ec5309e29f3..ac6d872ce067 100644

--- a/include/linux/pmem.h
+-+-+- b/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)