[PATCH v3] x86, pmem: use memcpy_mcsafe() for memcpy_from_pmem()

[PATCH v3] x86, pmem: use memcpy_mcsafe() for memcpy_from_pmem()

[Dan Williams]

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        |   21 +++++++++++++++------
 3 files changed, 26 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..cc948191a653 100644
--- a/include/linux/pmem.h
+++ b/include/linux/pmem.h
@@ -42,6 +42,12 @@ 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();
+}
+
 static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
 		struct iov_iter *i)
 {
@@ -66,14 +72,17 @@ 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)

Re: [PATCH v3] x86, pmem: use memcpy_mcsafe() for memcpy_from_pmem()

[Dan Williams]

On Mon, Mar 28, 2016 at 5:28 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> 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        |   21 +++++++++++++++------
>  3 files changed, 26 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..cc948191a653 100644
> --- a/include/linux/pmem.h
> +++ b/include/linux/pmem.h
> @@ -42,6 +42,12 @@ 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();
> +}

Note, the change in v3 was the addition of this stub to fix a build
error on !CONFIG_ARCH_HAS_PMEM_API archs.

Re: [PATCH v3] x86, pmem: use memcpy_mcsafe() for memcpy_from_pmem()

[Ingo Molnar]

* Dan Williams <dan.j.williams@intel.com> wrote:

> 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>

I suspect you want to carry this in the nvdimm tree? If so:

  Acked-by: Ingo Molnar <mingo@kernel.org>

Thanks,

	Ingo