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Subject[GIT PULL v2] libnvdimm, pmem: hook up memcpy_mcsafe
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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 <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: 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>
    Acked-by: Ingo Molnar <mingo@kernel.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        | 22 ++++++++++++++++------
 3 files changed, 27 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..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)

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