Subject: [PATCH v3 6/9] mm/mremap: Use range flush that does TLB and page walk cache flush

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Tue, 30 Mar 2021 11:37:49 +0530

Some architectures do have the concept of page walk cache which need
to be flush when updating higher levels of page tables. A fast mremap
that involves moving page table pages instead of copying pte entries
should flush page walk cache since the old translation cache is no more
valid.

Add new helper flush_pte_tlb_pwc_range() which invalidates both TLB and
page walk cache where TLB entries are mapped with page size PAGE_SIZE.

Signed-off-by: Aneesh Kumar K.V <[email-masked]>
---
 arch/powerpc/include/asm/book3s/64/tlbflush.h | 11 +++++++++++
 mm/mremap.c                                   | 15 +++++++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush.h b/arch/powerpc/include/asm/book3s/64/tlbflush.h
index efe5336e2b6f..b9022eb9f20e 100644
--- a/arch/powerpc/include/asm/book3s/64/tlbflush.h
+++ b/arch/powerpc/include/asm/book3s/64/tlbflush.h
@@ -80,6 +80,17 @@ static inline void flush_hugetlb_tlb_range(struct vm_area_struct *vma,
 	return flush_hugetlb_tlb_pwc_range(vma, start, end, false);
 }
 
+#define flush_pte_tlb_pwc_range flush_tlb_pwc_range
+static inline void flush_pte_tlb_pwc_range(struct vm_area_struct *vma,
+					   unsigned long start, unsigned long end,
+					   bool also_pwc)
+{
+	if (radix_enabled())
+		return radix__flush_tlb_pwc_range_psize(vma->vm_mm, start,
+							end, mmu_virtual_psize, also_pwc);
+	return hash__flush_tlb_range(vma, start, end);
+}
+
 static inline void flush_tlb_range(struct vm_area_struct *vma,
 				   unsigned long start, unsigned long end)
 {
diff --git a/mm/mremap.c b/mm/mremap.c
index 574287f9bb39..0e7b11daafee 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -210,6 +210,17 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
 		drop_rmap_locks(vma);
 }
 
+#ifndef flush_pte_tlb_pwc_range
+#define flush_pte_tlb_pwc_range flush_pte_tlb_pwc_range
+static inline void flush_pte_tlb_pwc_range(struct vm_area_struct *vma,
+					   unsigned long start,
+					   unsigned long end,
+					   bool also_pwc)
+{
+	return flush_tlb_range(vma, start, end);
+}
+#endif
+
 #ifdef CONFIG_HAVE_MOVE_PMD
 static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 		  unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
@@ -260,7 +271,7 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
 	VM_BUG_ON(!pmd_none(*new_pmd));
 	pmd_populate(mm, new_pmd, (pgtable_t)pmd_page_vaddr(pmd));
 
-	flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
+	flush_pte_tlb_pwc_range(vma, old_addr, old_addr + PMD_SIZE, true);
 	if (new_ptl != old_ptl)
 		spin_unlock(new_ptl);
 	spin_unlock(old_ptl);
@@ -307,7 +318,7 @@ static bool move_normal_pud(struct vm_area_struct *vma, unsigned long old_addr,
 	VM_BUG_ON(!pud_none(*new_pud));
 
 	pud_populate(mm, new_pud, (pmd_t *)pud_page_vaddr(pud));
-	flush_tlb_range(vma, old_addr, old_addr + PUD_SIZE);
+	flush_pte_tlb_pwc_range(vma, old_addr, old_addr + PUD_SIZE, true);
 	if (new_ptl != old_ptl)
 		spin_unlock(new_ptl);
 	spin_unlock(old_ptl);
-- 
2.30.2