x86: fix trimming e820 with MTRR holes.

converting MTRR layout from continous to discrete, some time could run out of
MTRRs. So add gran_sizek to prevent that by dumpping small RAM piece less than
gran_sizek.

previous trimming only can handle highest_pfn from mtrr to end_pfn from e820.
when have more than 4g RAM installed, there will be holes below 4g. so need to
check ram below 4g is coverred well.

need to be applied after
	[PATCH] x86: mtrr cleanup for converting continuous to discrete layout v7

Signed-off-by: Yinghai Lu <yinghai.lu@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 84 insertions, 17 deletions

diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index 8a6f68b45e3e..9ab5c16b0d52 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -1095,6 +1095,17 @@ int __init amd_special_default_mtrr(void)
 	return 0;
 }
 
+static u64 __init real_trim_memory(unsigned long start_pfn, unsigned long limit_pfn)
+{
+	u64 trim_start, trim_size;
+	trim_start =  start_pfn;
+	trim_start <<= PAGE_SHIFT;
+	trim_size = limit_pfn;
+	trim_size <<= PAGE_SHIFT;
+	trim_size -= trim_start;
+	return update_memory_range(trim_start, trim_size, E820_RAM,
+				E820_RESERVED);
+}
 /**
  * mtrr_trim_uncached_memory - trim RAM not covered by MTRRs
  * @end_pfn: ending page frame number
@@ -1110,8 +1121,13 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn)
 {
 	unsigned long i, base, size, highest_pfn = 0, def, dummy;
 	mtrr_type type;
-	u64 trim_start, trim_size;
+	struct res_range range[RANGE_NUM];
+	int nr_range;
+	u64 total_real_trim_size;
+	int changed;
 
+	/* extra one for all 0 */
+	int num[MTRR_NUM_TYPES + 1];
 	/*
 	 * Make sure we only trim uncachable memory on machines that
 	 * support the Intel MTRR architecture:
@@ -1123,9 +1139,6 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn)
 	if (def != MTRR_TYPE_UNCACHABLE)
 		return 0;
 
-	if (amd_special_default_mtrr())
-		return 0;
-
 	/* Find highest cached pfn */
 	for (i = 0; i < num_var_ranges; i++) {
 		mtrr_if->get(i, &base, &size, &type);
@@ -1145,26 +1158,80 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn)
 		return 0;
 	}
 
-	if (highest_pfn < end_pfn) {
+	/* check entries number */
+	memset(num, 0, sizeof(num));
+	for (i = 0; i < num_var_ranges; i++) {
+		mtrr_if->get(i, &base, &size, &type);
+		if (type >= MTRR_NUM_TYPES)
+			continue;
+		if (!size)
+			type = MTRR_NUM_TYPES;
+		num[type]++;
+	}
+
+	/* no entry for WB? */
+	if (!num[MTRR_TYPE_WRBACK])
+		return 0;
+
+	/* check if we only had WB and UC */
+	if (num[MTRR_TYPE_WRBACK] + num[MTRR_TYPE_UNCACHABLE] !=
+		num_var_ranges - num[MTRR_NUM_TYPES])
+		return 0;
+
+	memset(range, 0, sizeof(range));
+	nr_range = 0;
+	if (mtrr_tom2) {
+		range[nr_range].start = (1ULL<<(32 - PAGE_SHIFT));
+		range[nr_range].end = (mtrr_tom2 >> PAGE_SHIFT) - 1;
+		if (highest_pfn < range[nr_range].end + 1)
+			highest_pfn = range[nr_range].end + 1;
+		nr_range++;
+	}
+	nr_range = x86_get_mtrr_mem_range(range, nr_range, 0, 0);
+
+	changed = 0;
+	total_real_trim_size = 0;
+
+	/* check the top at first */
+	i = nr_range - 1;
+	if (range[i].end + 1 < end_pfn) {
+			total_real_trim_size += real_trim_memory(range[i].end + 1, end_pfn);
+	}
+
+	if (total_real_trim_size) {
 		printk(KERN_WARNING "WARNING: BIOS bug: CPU MTRRs don't cover"
-			" all of memory, losing %luMB of RAM.\n",
-			(end_pfn - highest_pfn) >> (20 - PAGE_SHIFT));
+			" all of memory, losing %lluMB of RAM.\n",
+			total_real_trim_size >> 20);
 
 		WARN_ON(1);
 
-		printk(KERN_INFO "update e820 for mtrr\n");
-		trim_start = highest_pfn;
-		trim_start <<= PAGE_SHIFT;
-		trim_size = end_pfn;
-		trim_size <<= PAGE_SHIFT;
-		trim_size -= trim_start;
-		update_memory_range(trim_start, trim_size, E820_RAM,
-					E820_RESERVED);
+		printk(KERN_INFO "update e820 for mtrr -- end_pfn\n");
 		update_e820();
-		return 1;
+		changed = 1;
 	}
 
-	return 0;
+	total_real_trim_size = 0;
+	if (range[0].start)
+		total_real_trim_size += real_trim_memory(0, range[0].start);
+
+	for (i = 0; i < nr_range - 1; i--) {
+		if (range[i].end + 1 < range[i+1].start)
+			total_real_trim_size += real_trim_memory(range[i].end + 1, range[i+1].start);
+	}
+
+	if (total_real_trim_size) {
+		printk(KERN_WARNING "WARNING: BIOS bug: CPU MTRRs don't cover"
+			" all of memory, losing %lluMB of RAM.\n",
+			total_real_trim_size >> 20);
+
+		WARN_ON(1);
+
+		printk(KERN_INFO "update e820 for mtrr -- holes\n");
+		update_e820();
+		changed = 1;
+	}
+
+	return changed;
 }
 
 /**