Subject: [PATCH] powerpc/mm: Use tlbiel only if we ever ran on the current cpu

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Mon, 24 Oct 2016 08:50:43 +0530

Before this patch, we used tlbiel, if we ever ran only on this core.
That was mostly derived from the nohash usage of the same. But the
ISA 3.0 clarifies tlbiel such that

"All TLB entries that have all of the following properties are made
invalid on the thread executing the tlbiel instruction"

Hence use tlbiel, if we only ever ran on just the current cpu.

Signed-off-by: Aneesh Kumar K.V <[email-masked]>
---

NOTE: May be the nohash usage also need to switch to mm_is_thread_local ?
I didn't check the spec, hence I left it unchanged.

I am also not adding a Fixes: line because there is no one commit. But
this is needed for radix enabled kernel. So a backport to 4.8 is needed.

 arch/powerpc/include/asm/tlb.h | 12 ++++++++++++
 arch/powerpc/mm/tlb-radix.c    |  8 ++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/asm/tlb.h
index f6f68f73e858..99e1397b71da 100644
--- a/arch/powerpc/include/asm/tlb.h
+++ b/arch/powerpc/include/asm/tlb.h
@@ -52,11 +52,23 @@ static inline int mm_is_core_local(struct mm_struct *mm)
 	return cpumask_subset(mm_cpumask(mm),
 			      topology_sibling_cpumask(smp_processor_id()));
 }
+
+static inline int mm_is_thread_local(struct mm_struct *mm)
+{
+	return cpumask_equal(mm_cpumask(mm),
+			      cpumask_of(smp_processor_id()));
+}
+
 #else
 static inline int mm_is_core_local(struct mm_struct *mm)
 {
 	return 1;
 }
+
+static inline int mm_is_thread_local(struct mm_struct *mm)
+{
+	return 1;
+}
 #endif
 
 #endif /* __KERNEL__ */
diff --git a/arch/powerpc/mm/tlb-radix.c b/arch/powerpc/mm/tlb-radix.c
index 0e49ec541ab5..bda8c43be78a 100644
--- a/arch/powerpc/mm/tlb-radix.c
+++ b/arch/powerpc/mm/tlb-radix.c
@@ -175,7 +175,7 @@ void radix__flush_tlb_mm(struct mm_struct *mm)
 	if (unlikely(pid == MMU_NO_CONTEXT))
 		goto no_context;
 
-	if (!mm_is_core_local(mm)) {
+	if (!mm_is_thread_local(mm)) {
 		int lock_tlbie = !mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE);
 
 		if (lock_tlbie)
@@ -201,7 +201,7 @@ void radix__flush_tlb_pwc(struct mmu_gather *tlb, unsigned long addr)
 	if (unlikely(pid == MMU_NO_CONTEXT))
 		goto no_context;
 
-	if (!mm_is_core_local(mm)) {
+	if (!mm_is_thread_local(mm)) {
 		int lock_tlbie = !mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE);
 
 		if (lock_tlbie)
@@ -226,7 +226,7 @@ void radix__flush_tlb_page_psize(struct mm_struct *mm, unsigned long vmaddr,
 	pid = mm ? mm->context.id : 0;
 	if (unlikely(pid == MMU_NO_CONTEXT))
 		goto bail;
-	if (!mm_is_core_local(mm)) {
+	if (!mm_is_thread_local(mm)) {
 		int lock_tlbie = !mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE);
 
 		if (lock_tlbie)
@@ -321,7 +321,7 @@ void radix__flush_tlb_range_psize(struct mm_struct *mm, unsigned long start,
 {
 	unsigned long pid;
 	unsigned long addr;
-	int local = mm_is_core_local(mm);
+	int local = mm_is_thread_local(mm);
 	unsigned long ap = mmu_get_ap(psize);
 	int lock_tlbie = !mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE);
 	unsigned long page_size = 1UL << mmu_psize_defs[psize].shift;
-- 
2.10.1