--- /dev/null
+/*
+ * Copyright(c) 2015 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#ifndef __ASM_X86_PMEM_H__
+#define __ASM_X86_PMEM_H__
+
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+#include <asm/cpufeature.h>
+#include <asm/special_insns.h>
+
+#ifdef CONFIG_ARCH_HAS_PMEM_API
+/**
+ * arch_memcpy_to_pmem - copy data to persistent memory
+ * @dst: destination buffer for the copy
+ * @src: source buffer for the copy
+ * @n: length of the copy in bytes
+ *
+ * Copy data to persistent memory media via non-temporal stores so that
+ * a subsequent arch_wmb_pmem() can flush cpu and memory controller
+ * write buffers to guarantee durability.
+ */
+static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
+ size_t n)
+{
+ int unwritten;
+
+ /*
+ * We are copying between two kernel buffers, if
+ * __copy_from_user_inatomic_nocache() returns an error (page
+ * fault) we would have already reported a general protection fault
+ * before the WARN+BUG.
+ */
+ unwritten = __copy_from_user_inatomic_nocache((void __force *) dst,
+ (void __user *) src, n);
+ if (WARN(unwritten, "%s: fault copying %p <- %p unwritten: %d\n",
+ __func__, dst, src, unwritten))
+ BUG();
+}
+
+/**
+ * arch_wmb_pmem - synchronize writes to persistent memory
+ *
+ * After a series of arch_memcpy_to_pmem() operations this drains data
+ * from cpu write buffers and any platform (memory controller) buffers
+ * to ensure that written data is durable on persistent memory media.
+ */
+static inline void arch_wmb_pmem(void)
+{
+ /*
+ * wmb() to 'sfence' all previous writes such that they are
+ * architecturally visible to 'pcommit'. Note, that we've
+ * already arranged for pmem writes to avoid the cache via
+ * arch_memcpy_to_pmem().
+ */
+ wmb();
+ pcommit_sfence();
+}
+
+/**
+ * __arch_wb_cache_pmem - write back a cache range with CLWB
+ * @vaddr: virtual start address
+ * @size: number of bytes to write back
+ *
+ * Write back a cache range using the CLWB (cache line write back)
+ * instruction. This function requires explicit ordering with an
+ * arch_wmb_pmem() call. This API is internal to the x86 PMEM implementation.
+ */
+static inline void __arch_wb_cache_pmem(void *vaddr, size_t size)
+{
+ u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;
+ unsigned long clflush_mask = x86_clflush_size - 1;
+ void *vend = vaddr + size;
+ void *p;
+
+ for (p = (void *)((unsigned long)vaddr & ~clflush_mask);
+ p < vend; p += x86_clflush_size)
+ clwb(p);
+}
+
+/*
+ * copy_from_iter_nocache() on x86 only uses non-temporal stores for iovec
+ * iterators, so for other types (bvec & kvec) we must do a cache write-back.
+ */
+static inline bool __iter_needs_pmem_wb(struct iov_iter *i)
+{
+ return iter_is_iovec(i) == false;
+}
+
+/**
+ * arch_copy_from_iter_pmem - copy data from an iterator to PMEM
+ * @addr: PMEM destination address
+ * @bytes: number of bytes to copy
+ * @i: iterator with source data
+ *
+ * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'.
+ * This function requires explicit ordering with an arch_wmb_pmem() call.
+ */
+static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
+ struct iov_iter *i)
+{
+ void *vaddr = (void __force *)addr;
+ size_t len;
+
+ /* TODO: skip the write-back by always using non-temporal stores */
+ len = copy_from_iter_nocache(vaddr, bytes, i);
+
+ if (__iter_needs_pmem_wb(i))
+ __arch_wb_cache_pmem(vaddr, bytes);
+
+ return len;
+}
+
+/**
+ * arch_clear_pmem - zero a PMEM memory range
+ * @addr: virtual start address
+ * @size: number of bytes to zero
+ *
+ * Write zeros into the memory range starting at 'addr' for 'size' bytes.
+ * This function requires explicit ordering with an arch_wmb_pmem() call.
+ */
+static inline void arch_clear_pmem(void __pmem *addr, size_t size)
+{
+ void *vaddr = (void __force *)addr;
+
+ /* TODO: implement the zeroing via non-temporal writes */
+ if (size == PAGE_SIZE && ((unsigned long)vaddr & ~PAGE_MASK) == 0)
+ clear_page(vaddr);
+ else
+ memset(vaddr, 0, size);
+
+ __arch_wb_cache_pmem(vaddr, size);
+}
+
+static inline bool __arch_has_wmb_pmem(void)
+{
+ /*
+ * We require that wmb() be an 'sfence', that is only guaranteed on
+ * 64-bit builds
+ */
+ return static_cpu_has(X86_FEATURE_PCOMMIT);
+}
+#endif /* CONFIG_ARCH_HAS_PMEM_API */
+#endif /* __ASM_X86_PMEM_H__ */
Code Review / kvmfornfv.git / blobdiff