arm64: hugetlb: enable __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE

It is better to use huge page size instead of PAGE_SIZE for stride when
flush hugepage, which reduces the loop in __flush_tlb_range().

Let's support arch's flush_hugetlb_tlb_range(), which is used in
hugetlb_unshare_all_pmds(), move_hugetlb_page_tables() and
hugetlb_change_protection() for now.

Note,: for hugepages based on contiguous bit, it has to be invalidated
individually since the contiguous PTE bit is just a hint, the hardware may
or may not take it into account.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Reviewed-by: Muchun Song <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Kalesh Singh <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: William Kucharski <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

arch/arm64/include/asm/hugetlb.h

@@ -60,4 +60,19 @@ extern void huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
 
 #include <asm-generic/hugetlb.h>
 
+#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)
+{
+	unsigned long stride = huge_page_size(hstate_vma(vma));
+
+	if (stride == PMD_SIZE)
+		__flush_tlb_range(vma, start, end, stride, false, 2);
+	else if (stride == PUD_SIZE)
+		__flush_tlb_range(vma, start, end, stride, false, 1);
+	else
+		__flush_tlb_range(vma, start, end, PAGE_SIZE, false, 0);
+}
+
 #endif /* __ASM_HUGETLB_H */