[RFC PATCH 4/4] mm: support Svnapot in huge vmap

[Qinglin Pan]

From: Qinglin Pan <panqinglin2020 at iscas.ac.cn>

The HAVE_ARCH_HUGE_VMAP option can be used to help implement arch
special huge vmap size. This patch selects this option by default and
re-writes the arch_vmap_pte_range_map_size for Svnapot 64KB size.

It can be tested when booting kernel in qemu with pci device, which
will make the kernel to call pci driver using ioremap, and the
re-written function will be called.

Signed-off-by: Qinglin Pan <panqinglin2020 at iscas.ac.cn>
---
 arch/riscv/Kconfig               |  1 +
 arch/riscv/include/asm/pgtable.h | 35 ++++++++++++++++++++++++++++++++
 arch/riscv/include/asm/vmalloc.h | 18 ++++++++++++++++
 3 files changed, 54 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 0ae025686faf..4a57fd56daf8 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -13,6 +13,7 @@ config 32BIT
 config RISCV
 	def_bool y
 	select ARCH_CLOCKSOURCE_INIT
+  select HAVE_ARCH_HUGE_VMAP
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
 	select ARCH_HAS_BINFMT_FLAT
 	select ARCH_HAS_DEBUG_VM_PGTABLE
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index adacb877433d..218d95d30bfa 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -642,6 +642,41 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+static inline int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
+{
+	return 0;
+}
+
+static inline int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
+{
+	return 0;
+}
+
+static inline int pud_clear_huge(pud_t *pud)
+{
+	return 0;
+}
+
+static inline int pmd_clear_huge(pmd_t *pmd)
+{
+	return 0;
+}
+
+static inline int p4d_free_pud_page(p4d_t *p4d, unsigned long addr)
+{
+	return 0;
+}
+
+static inline int pud_free_pmd_page(pud_t *pud, unsigned long addr)
+{
+	return 0;
+}
+
+static inline int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
+{
+	return 0;
+}
+
 /*
  * Encode and decode a swap entry
  *
diff --git a/arch/riscv/include/asm/vmalloc.h b/arch/riscv/include/asm/vmalloc.h
index ff9abc00d139..fecfa24d6a13 100644
--- a/arch/riscv/include/asm/vmalloc.h
+++ b/arch/riscv/include/asm/vmalloc.h
@@ -1,4 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 #ifndef _ASM_RISCV_VMALLOC_H
 #define _ASM_RISCV_VMALLOC_H
 
+#include <asm/pgtable-bits.h>
+
+#define arch_vmap_pte_range_map_size arch_vmap_pte_range_map_size
+static inline unsigned long arch_vmap_pte_range_map_size(unsigned long addr, unsigned long end,
+		u64 pfn, unsigned int max_page_shift)
+{
+	bool is_napot_addr = !(addr & NAPOT_CONT64KB_MASK);
+	bool pfn_align_napot = !(pfn & (NAPOT_64KB_PTE_NUM - 1UL));
+	bool space_enough = ((end - addr) >= NAPOT_CONT64KB_SIZE);
+
+	if (is_napot_addr && pfn_align_napot && space_enough
+			&& max_page_shift >= NAPOT_CONT64KB_SHIFT)
+		return NAPOT_CONT64KB_SIZE;
+
+	return PAGE_SIZE;
+}
+
 #endif /* _ASM_RISCV_VMALLOC_H */
-- 
2.32.0