[RFC PATCH] powerpc/tlb: enable arch want batched unmap tlb flush

[Luming Yu]

From: Yu Luming <luming.yu at gmail.com>

ppc always do its own tracking for batch tlb. By trivially enabling
the ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH in ppc, ppc arch can re-use
common code in rmap and reduce overhead and do optimization it could not
have without a tlb flushing context at low architecture level.

Signed-off-by: Luming Yu <luming.yu at shingroup.cn>
---
 arch/powerpc/Kconfig                |  1 +
 arch/powerpc/include/asm/tlbbatch.h | 30 +++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 arch/powerpc/include/asm/tlbbatch.h

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index e94e7e4bfd40..e6db84dd014a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -175,6 +175,7 @@ config PPC
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select ARCH_WANT_IRQS_OFF_ACTIVATE_MM
 	select ARCH_WANT_LD_ORPHAN_WARN
+	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
 	select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP	if PPC_RADIX_MMU
 	select ARCH_WANTS_MODULES_DATA_IN_VMALLOC	if PPC_BOOK3S_32 || PPC_8xx
 	select ARCH_WEAK_RELEASE_ACQUIRE
diff --git a/arch/powerpc/include/asm/tlbbatch.h b/arch/powerpc/include/asm/tlbbatch.h
new file mode 100644
index 000000000000..484628460057
--- /dev/null
+++ b/arch/powerpc/include/asm/tlbbatch.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ARCH_PPC_TLBBATCH_H
+#define _ARCH_PPC_TLBBATCH_H
+
+struct arch_tlbflush_unmap_batch {
+	/*
+         *
+	 */
+};
+
+static inline void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
+{
+}
+
+static inline void arch_tlbbatch_add_pending(struct arch_tlbflush_unmap_batch *batch,
+						struct mm_struct *mm,
+						unsigned long uarddr)
+{
+}
+
+static inline bool arch_tlbbatch_should_defer(struct mm_struct *mm)
+{
+	/*ppc always do tlb flush in batch*/
+	return false;
+}
+
+static inline void arch_flush_tlb_batched_pending(struct mm_struct *mm)
+{
+}
+#endif /* _ARCH_PPC_TLBBATCH_H */
-- 
2.42.0.windows.2