LoongArch: Consolidate max_pfn & max_low_pfn calculation

Now there 5 places which calculate max_pfn & max_low_pfn:
1. in fdt_setup() for FDT systems;
2. in memblock_init() for ACPI systems;
3. in init_numa_memory() for NUMA systems;
4. in arch_mem_init() to recalculate for "mem=" cmdline;
5. in paging_init() to recalculate for NUMA systems.

Since memblock_init() is called both for ACPI and FDT systems, move the
calculation out of the for_each_efi_memory_desc() loop can eliminate the
first case. The last case is very questionable (may be derived from the
MIPS/Loongson code) and breaks the "mem=" cmdline, so should be removed.
And then the NUMA version of paging_init() can be also eliminated.

After consolidation there are 3 places of calculation:
1. in memblock_init() for both ACPI and FDT systems;
2. in init_numa_memory() to recalculate for NUMA systems;
3. in arch_mem_init() to recalculate for the "mem=" cmdline.

For all cases the calculation is:
max_pfn = PFN_DOWN(memblock_end_of_DRAM());
max_low_pfn = min(PFN_DOWN(HIGHMEM_START), max_pfn);

Cc: stable@vger.kernel.org
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 2 insertions, 3 deletions

diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 69c17d162fff..25a87378e48e 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -294,8 +294,6 @@ static void __init fdt_setup(void)
 
 	early_init_dt_scan(fdt_pointer, __pa(fdt_pointer));
 	early_init_fdt_reserve_self();
-
-	max_low_pfn = PFN_PHYS(memblock_end_of_DRAM());
 #endif
 }
 
@@ -390,7 +388,8 @@ static void __init check_kernel_sections_mem(void)
 static void __init arch_mem_init(char **cmdline_p)
 {
 	/* Recalculate max_low_pfn for "mem=xxx" */
-	max_pfn = max_low_pfn = PHYS_PFN(memblock_end_of_DRAM());
+	max_pfn = PFN_DOWN(memblock_end_of_DRAM());
+	max_low_pfn = min(PFN_DOWN(HIGHMEM_START), max_pfn);
 
 	if (usermem)
 		pr_info("User-defined physical RAM map overwrite\n");