riscv: mm: support Svnapot in huge vmap

As HAVE_ARCH_HUGE_VMAP and HAVE_ARCH_HUGE_VMALLOC is supported, we can
implement arch_vmap_pte_range_map_size and arch_vmap_pte_supported_shift
for Svnapot to support huge vmap about napot size.

It can be tested by huge vmap used in pci driver. Huge vmalloc with svnapot
can be tested by test_vmalloc with [1] applied, and probe this
module to run fix_size_alloc_test with use_huge true.

[1]https://lore.kernel.org/all/20221212055657.698420-1-panqinglin2020@iscas.ac.cn/

Signed-off-by: Qinglin Pan <panqinglin00@gmail.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230209131647.17245-4-panqinglin00@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: PanQL

arch/riscv/include/asm/vmalloc.h

@@ -17,6 +17,65 @@ static inline bool arch_vmap_pmd_supported(pgprot_t prot)
 	return true;
 }
 
-#endif
+#ifdef CONFIG_RISCV_ISA_SVNAPOT
+#include <linux/pgtable.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)
+{
+	unsigned long map_size = PAGE_SIZE;
+	unsigned long size, order;
+
+	if (!has_svnapot())
+		return map_size;
+
+	for_each_napot_order_rev(order) {
+		if (napot_cont_shift(order) > max_page_shift)
+			continue;
+
+		size = napot_cont_size(order);
+		if (end - addr < size)
+			continue;
+
+		if (!IS_ALIGNED(addr, size))
+			continue;
+
+		if (!IS_ALIGNED(PFN_PHYS(pfn), size))
+			continue;
+
+		map_size = size;
+		break;
+	}
+
+	return map_size;
+}
+
+#define arch_vmap_pte_supported_shift arch_vmap_pte_supported_shift
+static inline int arch_vmap_pte_supported_shift(unsigned long size)
+{
+	int shift = PAGE_SHIFT;
+	unsigned long order;
+
+	if (!has_svnapot())
+		return shift;
+
+	WARN_ON_ONCE(size >= PMD_SIZE);
+
+	for_each_napot_order_rev(order) {
+		if (napot_cont_size(order) > size)
+			continue;
+
+		if (!IS_ALIGNED(size, napot_cont_size(order)))
+			continue;
+
+		shift = napot_cont_shift(order);
+		break;
+	}
+
+	return shift;
+}
+
+#endif /* CONFIG_RISCV_ISA_SVNAPOT */
+#endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
 #endif /* _ASM_RISCV_VMALLOC_H */