x86: mtrr_cleanup try gran_size to less than 1M

one have gran < 1M

reg00: base=0xd8000000 (3456MB), size= 128MB: uncachable, count=1
reg01: base=0xe0000000 (3584MB), size= 512MB: uncachable, count=1
reg02: base=0x00000000 (   0MB), size=4096MB: write-back, count=1
reg03: base=0x100000000 (4096MB), size= 512MB: write-back, count=1
reg04: base=0x120000000 (4608MB), size= 128MB: write-back, count=1
reg05: base=0xd7f80000 (3455MB), size= 512KB: uncachable, count=1

will get

Found optimal setting for mtrr clean up
gran_size: 512K         chunk_size: 2M  num_reg: 7      lose RAM: 0G
range0: 0000000000000000 - 00000000d8000000
Setting variable MTRR 0, base: 0GB, range: 2GB, type WB
Setting variable MTRR 1, base: 2GB, range: 1GB, type WB
Setting variable MTRR 2, base: 3GB, range: 256MB, type WB
Setting variable MTRR 3, base: 3328MB, range: 128MB, type WB
hole: 00000000d7f00000 - 00000000d7f80000
Setting variable MTRR 4, base: 3455MB, range: 512KB, type UC
rangeX: 0000000100000000 - 0000000128000000
Setting variable MTRR 5, base: 4GB, range: 512MB, type WB
Setting variable MTRR 6, base: 4608MB, range: 128MB, type WB

so start from 64k instead of 1M
Signed-off-by: NYinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

arch/x86/kernel/cpu/mtrr/main.c

@@ -1197,11 +1197,11 @@ struct mtrr_cleanup_result {
 };
 
 /*
- * gran_size: 1M, 2M, ..., 2G
+ * gran_size: 64K, 128K, 256K, 512K, 1M, 2M, ..., 2G
  * chunk size: gran_size, ..., 2G
- * so we need (1+12)*6
+ * so we need (1+16)*8
  */
-#define NUM_RESULT	78
+#define NUM_RESULT	136
 #define PSHIFT		(PAGE_SHIFT - 10)
 
 static struct mtrr_cleanup_result __initdata result[NUM_RESULT];
@@ -1323,7 +1323,7 @@ static int __init mtrr_cleanup(unsigned address_bits)
 	i = 0;
 	memset(min_loss_pfn, 0xff, sizeof(min_loss_pfn));
 	memset(result, 0, sizeof(result));
-	for (gran_size = (1ULL<<20); gran_size < (1ULL<<32); gran_size <<= 1) {
+	for (gran_size = (1ULL<<16); gran_size < (1ULL<<32); gran_size <<= 1) {
 		char gran_factor;
 		unsigned long gran_base;