x86-64: reduce range spanned by 1:1 mapping and frame table indexes

Introduces a virtual space conserving transformation on the MFN thus
far used to index 1:1 mapping and frame table, removing the largest
range of contiguous bits (below the most significant one) which are
zero for all valid MFNs from the MFN representation, to be used to
index into those arrays, thereby cutting the virtual range these
tables must cover approximately by half with each bit removed.

Since this should account for hotpluggable memory (in order to not
requiring a re-write when that gets supported), the determination of
which bits are candidates for removal must not be based on the E820
information, but instead has to use the SRAT. That in turn requires a
change to the ordering of steps done during early boot.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

1 files changed, 64 insertions, 0 deletions

diff --git a/xen/arch/x86/srat.c b/xen/arch/x86/srat.c
index 1a6d2a10fb..9ee4f3106e 100644
--- a/xen/arch/x86/srat.c
+++ b/xen/arch/x86/srat.c
@@ -286,6 +286,70 @@ static void unparse_node(int node)
 
 void __init acpi_numa_arch_fixup(void) {}
 
+#ifdef __x86_64__
+
+static u64 __initdata srat_region_mask;
+
+static u64 __init fill_mask(u64 mask)
+{
+	while (mask & (mask + 1))
+		mask |= mask + 1;
+	return mask;
+}
+
+static int __init srat_parse_region(struct acpi_subtable_header *header,
+				    const unsigned long end)
+{
+	struct acpi_srat_mem_affinity *ma;
+
+	if (!header)
+		return -EINVAL;
+
+	ma = container_of(header, struct acpi_srat_mem_affinity, header);
+
+	if (!ma->length ||
+	    !(ma->flags & ACPI_SRAT_MEM_ENABLED) ||
+	    (ma->flags & ACPI_SRAT_MEM_NON_VOLATILE))
+		return 0;
+
+	if (numa_off)
+		printk(KERN_INFO "SRAT: %013"PRIx64"-%013"PRIx64"\n",
+		       ma->base_address, ma->base_address + ma->length - 1);
+
+	srat_region_mask |= ma->base_address |
+			    fill_mask(ma->base_address ^
+				      (ma->base_address + ma->length - 1));
+
+	return 0;
+}
+
+void __init srat_parse_regions(u64 addr)
+{
+	u64 mask;
+	unsigned int i;
+
+	if (acpi_disabled || acpi_numa < 0 ||
+	    acpi_table_parse(ACPI_SIG_SRAT, acpi_parse_srat))
+		return;
+
+	srat_region_mask = fill_mask(addr - 1);
+	acpi_table_parse_srat(ACPI_SRAT_MEMORY_AFFINITY, srat_parse_region, 0);
+
+	for (mask = srat_region_mask, i = 0; mask && i < e820.nr_map; i++) {
+		if (e820.map[i].type != E820_RAM)
+			continue;
+
+		if (~mask &
+		    fill_mask(e820.map[i].addr ^
+			      (e820.map[i].addr + e820.map[i].size - 1)))
+			mask = 0;
+	}
+
+	pfn_pdx_hole_setup(mask >> PAGE_SHIFT);
+}
+
+#endif /* __x86_64__ */
+
 /* Use the information discovered above to actually set up the nodes. */
 int __init acpi_scan_nodes(u64 start, u64 end)
 {