Let arm64 subscribe to the previously added framework in which architecture
can inform whether a given huge page size is supported for migration. This
just overrides the default function arch_hugetlb_migration_supported() and
enables migration for all possible HugeTLB page sizes on arm64. With this,
HugeTLB migration support on arm64 now covers all possible HugeTLB options.

        CONT PTE    PMD    CONT PMD    PUD
        --------    ---    --------    ---
4K:        64K      2M        32M      1G
16K:        2M     32M         1G
64K:        2M    512M        16G

Reviewed-by: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>
Reviewed-by: Steve Capper <steve.cap...@arm.com>
Acked-by: Catalin Marinas <catalin.mari...@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khand...@arm.com>
---
 arch/arm64/include/asm/hugetlb.h |  5 +++++
 arch/arm64/mm/hugetlbpage.c      | 20 ++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
index fb66098..c6a07a3 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -20,6 +20,11 @@
 
 #include <asm/page.h>
 
+#ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
+#define arch_hugetlb_migration_supported arch_hugetlb_migration_supported
+extern bool arch_hugetlb_migration_supported(struct hstate *h);
+#endif
+
 #define __HAVE_ARCH_HUGE_PTEP_GET
 static inline pte_t huge_ptep_get(pte_t *ptep)
 {
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index f58ea50..e445500 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -27,6 +27,26 @@
 #include <asm/tlbflush.h>
 #include <asm/pgalloc.h>
 
+#ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
+bool arch_hugetlb_migration_supported(struct hstate *h)
+{
+       size_t pagesize = huge_page_size(h);
+
+       switch (pagesize) {
+#ifdef CONFIG_ARM64_4K_PAGES
+       case PUD_SIZE:
+#endif
+       case PMD_SIZE:
+       case CONT_PMD_SIZE:
+       case CONT_PTE_SIZE:
+               return true;
+       }
+       pr_warn("%s: unrecognized huge page size 0x%lx\n",
+                       __func__, pagesize);
+       return false;
+}
+#endif
+
 int pmd_huge(pmd_t pmd)
 {
        return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
-- 
2.7.4

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