Re: [RFC 3/4] powerpc: Add pmem API support

[Dan Williams]

On Tue, Jun 27, 2017 at 3:28 AM, Oliver O'Halloran  wrote:
> Adds powerpc64 implementations of:
>
> memcpy_flushcache()
> arch_wb_cache_pmem()
> arch_invalidate_pmem()
>
> Which form the architecture-specific portition of the persistent memory
> API. These functions provide cache-management primitives for the DAX
> drivers and libNVDIMM.
>

Ok, now that we have commit 0aed55af8834 "x86, uaccess: introduce
copy_from_iter_flushcache for pmem / cache-bypass operations" upstream
that changes the model for how an architecture advertises
pmem-specific cache management routines. CONFIG_ARCH_HAS_PMEM_API
causes the pmem driver to try to link to these helpers rather than
dummy fallbacks:

arch_wb_cache_pmem
arch_invalidate_pmem

and CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE indicates that the arch has
all the needed "flushcache" apis:

__copy_from_user_flushcache
memcpy_page_flushcache
memcpy_flushcache

[RFC 3/4] powerpc: Add pmem API support

[Oliver O'Halloran]

Adds powerpc64 implementations of:

memcpy_flushcache()
arch_wb_cache_pmem()
arch_invalidate_pmem()

Which form the architecture-specific portition of the persistent memory
API. These functions provide cache-management primitives for the DAX
drivers and libNVDIMM.

Signed-off-by: Oliver O'Halloran 
---
This should go on to of the ZONE_DEVICE patches. If you want a full tree
there's one here that's based on next-20170626 with Dan's libnvdimm-pending
branch merged in: https://github.com/oohal/linux/tree/ppc-nvdimm-4.13
---
 arch/powerpc/Kconfig|  1 +
 arch/powerpc/include/asm/pmem.h | 42 +
 2 files changed, 43 insertions(+)
 create mode 100644 arch/powerpc/include/asm/pmem.h

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 4526c9ba09b6..f551f3a26130 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -127,6 +127,7 @@ config PPC
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_GCOV_PROFILE_ALL
+   select ARCH_HAS_PMEM_APIif PPC64
select ARCH_HAS_SCALED_CPUTIME  if VIRT_CPU_ACCOUNTING_NATIVE
select ARCH_HAS_SG_CHAIN
select ARCH_HAS_TICK_BROADCAST  if GENERIC_CLOCKEVENTS_BROADCAST
diff --git a/arch/powerpc/include/asm/pmem.h b/arch/powerpc/include/asm/pmem.h
new file mode 100644
index ..7b0282e420fc
--- /dev/null
+++ b/arch/powerpc/include/asm/pmem.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright(c) 2017 IBM 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_PMEM_H__
+#define __ASM_PMEM_H__
+
+#include 
+#include 
+
+#ifdef CONFIG_ARCH_HAS_PMEM_API
+static inline void arch_wb_cache_pmem(void *addr, size_t size)
+{
+   unsigned long start = (unsigned long) addr;
+   flush_inval_dcache_range(start, start + size);
+}
+
+static inline void arch_invalidate_pmem(void *addr, size_t size)
+{
+   unsigned long start = (unsigned long) addr;
+   flush_inval_dcache_range(start, start + size);
+}
+
+static inline void *memcpy_flushcache(void *dest, const void *src, size_t size)
+{
+   unsigned long start = (unsigned long) dest;
+
+   memcpy(dest, src, size);
+   flush_inval_dcache_range(start, start + size);
+
+   return dest;
+}
+#endif /* CONFIG_ARCH_HAS_PMEM_API */
+#endif /* __ASM_PMEM_H__ */
-- 
2.9.4