riscv/mm: Enable THP migration

Add two THP helpers required to create PMD migration swap entries,
and enable THP migration via ARCH_ENABLE_THP_MIGRATION. This can
reduce time of THP migration without splitting and guarantee the
migrated pages are still contiguous.

Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 09e5b9f31d04974552bb27bdf00275681bbee4ea..de89279c8f57613769500a2ae543e682c03165e4 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -76,6 +76,7 @@ config RISCV
        select HAVE_ARCH_SECCOMP_FILTER
        select HAVE_ARCH_TRACEHOOK
        select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU
+       select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
        select HAVE_ARCH_THREAD_STRUCT_WHITELIST
        select HAVE_ARCH_VMAP_STACK if MMU && 64BIT
        select HAVE_ASM_MODVERSIONS

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 34230c27735870a515bd52f57a445503c3a2f82f..67f687aee673e33dc17130b923a699c8c5567c82 100644 (file)
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -649,6 +649,11 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
 #define __pte_to_swp_entry(pte)        ((swp_entry_t) { pte_val(pte) })
 #define __swp_entry_to_pte(x)  ((pte_t) { (x).val })
 
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+#define __pmd_to_swp_entry(pmd) ((swp_entry_t) { pmd_val(pmd) })
+#define __swp_entry_to_pmd(swp) __pmd((swp).val)
+#endif /* CONFIG_ARCH_ENABLE_THP_MIGRATION */
+
 /*
  * In the RV64 Linux scheme, we give the user half of the virtual-address space
  * and give the kernel the other (upper) half.