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