riscv: mm: call best_map_size many times during linear-mapping

Modify the best_map_size function to give map_size many times instead
of only once, so a memory region can be mapped by both PMD_SIZE and
PAGE_SIZE.
Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20221128023643.329091-1-panqinglin2020@iscas.ac.cnSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/mm/init.c

@@ -673,10 +673,11 @@ void __init create_pgd_mapping(pgd_t *pgdp,
 static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
 {
 	/* Upgrade to PMD_SIZE mappings whenever possible */
-	if ((base & (PMD_SIZE - 1)) || (size & (PMD_SIZE - 1)))
-		return PAGE_SIZE;
+	base &= PMD_SIZE - 1;
+	if (!base && size >= PMD_SIZE)
+		return PMD_SIZE;
 
-	return PMD_SIZE;
+	return PAGE_SIZE;
 }
 
 #ifdef CONFIG_XIP_KERNEL
@@ -1111,9 +1112,9 @@ static void __init setup_vm_final(void)
 		if (end >= __pa(PAGE_OFFSET) + memory_limit)
 			end = __pa(PAGE_OFFSET) + memory_limit;
 
-		map_size = best_map_size(start, end - start);
 		for (pa = start; pa < end; pa += map_size) {
 			va = (uintptr_t)__va(pa);
+			map_size = best_map_size(pa, end - pa);
 
 			create_pgd_mapping(swapper_pg_dir, va, pa, map_size,
 					   pgprot_from_va(va));