powerpc/mm/hugetlb: Add flush_hugetlb_tlb_range

Some archs like ppc64 need to do special things when flushing tlb for
hugepage. Add a new helper to flush hugetlb tlb range. This helps us to
avoid flushing the entire tlb mapping for the pid.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/book3s/64/tlbflush-radix.h

@@ -10,6 +10,8 @@ static inline int mmu_get_ap(int psize)
 	return mmu_psize_defs[psize].ap;
 }
 
+extern void radix__flush_hugetlb_tlb_range(struct vm_area_struct *vma,
+					   unsigned long start, unsigned long end);
 extern void radix__flush_tlb_range_psize(struct mm_struct *mm, unsigned long start,
 					 unsigned long end, int psize);
 extern void radix__flush_pmd_tlb_range(struct vm_area_struct *vma,

arch/powerpc/include/asm/book3s/64/tlbflush.h

@@ -16,6 +16,16 @@ static inline void flush_pmd_tlb_range(struct vm_area_struct *vma,
 	return hash__flush_tlb_range(vma, start, end);
 }
 
+#define __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
+static inline void flush_hugetlb_tlb_range(struct vm_area_struct *vma,
+					   unsigned long start,
+					   unsigned long end)
+{
+	if (radix_enabled())
+		return radix__flush_hugetlb_tlb_range(vma, start, end);
+	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)
 {

arch/powerpc/mm/hugetlbpage-radix.c

@@ -25,6 +25,16 @@ void radix__local_flush_hugetlb_page(struct vm_area_struct *vma, unsigned long v
 	radix__local_flush_tlb_page_psize(vma->vm_mm, vmaddr, psize);
 }
 
+void radix__flush_hugetlb_tlb_range(struct vm_area_struct *vma, unsigned long start,
+				   unsigned long end)
+{
+	int psize;
+	struct hstate *hstate = hstate_file(vma->vm_file);
+
+	psize = hstate_get_psize(hstate);
+	radix__flush_tlb_range_psize(vma->vm_mm, start, end, psize);
+}
+
 /*
  * A vairant of hugetlb_get_unmapped_area doing topdown search
  * FIXME!! should we do as x86 does or non hugetlb area does ?

mm/hugetlb.c

@@ -3938,6 +3938,14 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	return i ? i : -EFAULT;
 }
 
+#ifndef __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
+/*
+ * ARCHes with special requirements for evicting HUGETLB backing TLB entries can
+ * implement this.
+ */
+#define flush_hugetlb_tlb_range(vma, addr, end)	flush_tlb_range(vma, addr, end)
+#endif
+
 unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
 		unsigned long address, unsigned long end, pgprot_t newprot)
 {
@@ -3998,7 +4006,7 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
 	 * once we release i_mmap_rwsem, another task can do the final put_page
 	 * and that page table be reused and filled with junk.
 	 */
-	flush_tlb_range(vma, start, end);
+	flush_hugetlb_tlb_range(vma, start, end);
 	mmu_notifier_invalidate_range(mm, start, end);
 	i_mmap_unlock_write(vma->vm_file->f_mapping);
 	mmu_notifier_invalidate_range_end(mm, start, end);