Subject: [RFC PATCH 2/3] powerpc/mm/book3s64/radix: Use freed_tables instead of need_flush_all

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Tue, 3 Sep 2019 18:10:53 +0530

With commit: 22a61c3c4f13 ("asm-generic/tlb: Track freeing of page-table
directories in struct mmu_gather") we now track whether we freed page
table in mmu_gather. Use that to decide whether to flush Page Walk Cache.

Signed-off-by: Aneesh Kumar K.V <[email-masked]>
---
 arch/powerpc/include/asm/book3s/64/pgalloc.h  | 15 ---------------
 arch/powerpc/include/asm/book3s/64/tlbflush.h | 15 ---------------
 arch/powerpc/mm/book3s64/radix_tlb.c          | 11 +++--------
 3 files changed, 3 insertions(+), 38 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgalloc.h b/arch/powerpc/include/asm/book3s/64/pgalloc.h
index d5a44912902f..f6968c811026 100644
--- a/arch/powerpc/include/asm/book3s/64/pgalloc.h
+++ b/arch/powerpc/include/asm/book3s/64/pgalloc.h
@@ -122,11 +122,6 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
 				  unsigned long address)
 {
-	/*
-	 * By now all the pud entries should be none entries. So go
-	 * ahead and flush the page walk cache
-	 */
-	flush_tlb_pgtable(tlb, address);
 	pgtable_free_tlb(tlb, pud, PUD_INDEX);
 }
 
@@ -143,11 +138,6 @@ static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
 static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
 				  unsigned long address)
 {
-	/*
-	 * By now all the pud entries should be none entries. So go
-	 * ahead and flush the page walk cache
-	 */
-	flush_tlb_pgtable(tlb, address);
 	return pgtable_free_tlb(tlb, pmd, PMD_INDEX);
 }
 
@@ -166,11 +156,6 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t table,
 				  unsigned long address)
 {
-	/*
-	 * By now all the pud entries should be none entries. So go
-	 * ahead and flush the page walk cache
-	 */
-	flush_tlb_pgtable(tlb, address);
 	pgtable_free_tlb(tlb, table, PTE_INDEX);
 }
 
diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush.h b/arch/powerpc/include/asm/book3s/64/tlbflush.h
index ebf572ea621e..250399fa2459 100644
--- a/arch/powerpc/include/asm/book3s/64/tlbflush.h
+++ b/arch/powerpc/include/asm/book3s/64/tlbflush.h
@@ -147,19 +147,4 @@ static inline void flush_tlb_fix_spurious_fault(struct vm_area_struct *vma,
 		flush_tlb_page(vma, address);
 }
 
-/*
- * flush the page walk cache for the address
- */
-static inline void flush_tlb_pgtable(struct mmu_gather *tlb, unsigned long address)
-{
-	/*
-	 * Flush the page table walk cache on freeing a page table. We already
-	 * have marked the upper/higher level page table entry none by now.
-	 * So it is safe to flush PWC here.
-	 */
-	if (!radix_enabled())
-		return;
-
-	radix__flush_tlb_pwc(tlb, address);
-}
 #endif /*  _ASM_POWERPC_BOOK3S_64_TLBFLUSH_H */
diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c
index 059fef601eb9..dc395152e973 100644
--- a/arch/powerpc/mm/book3s64/radix_tlb.c
+++ b/arch/powerpc/mm/book3s64/radix_tlb.c
@@ -616,18 +616,13 @@ static void __flush_all_mm(struct mm_struct *mm, bool fullmm)
 	}
 	preempt_enable();
 }
+
 void radix__flush_all_mm(struct mm_struct *mm)
 {
 	__flush_all_mm(mm, false);
 }
 EXPORT_SYMBOL(radix__flush_all_mm);
 
-void radix__flush_tlb_pwc(struct mmu_gather *tlb, unsigned long addr)
-{
-	tlb->need_flush_all = 1;
-}
-EXPORT_SYMBOL(radix__flush_tlb_pwc);
-
 void radix__flush_tlb_page_psize(struct mm_struct *mm, unsigned long vmaddr,
 				 int psize)
 {
@@ -866,12 +861,12 @@ void radix__tlb_flush(struct mmu_gather *tlb)
 	if (tlb->fullmm) {
 		__flush_all_mm(mm, true);
 	} else if ( (psize = radix_get_mmu_psize(page_size)) == -1) {
-		if (!tlb->need_flush_all)
+		if (!tlb->freed_tables)
 			radix__flush_tlb_mm(mm);
 		else
 			radix__flush_all_mm(mm);
 	} else {
-		if (!tlb->need_flush_all)
+		if (!tlb->freed_tables)
 			radix__flush_tlb_range_psize(mm, start, end, psize);
 		else
 			radix__flush_tlb_pwc_range_psize(mm, start, end, psize);
-- 
2.21.0