x86: Exclude E820_RESERVED regions and memory holes above 4 GB from direct mapping.

commit 1bbbbe779aabe1f0768c2bf8f8c0a5583679b54a upstream.

On systems with very large memory (1 TB in our case), BIOS may report a
reserved region or a hole in the E820 map, even above the 4 GB range. Exclude
these from the direct mapping.

[ hpa: this should be done not just for > 4 GB but for everything above the legacy
  region (1 MB), at the very least.  That, however, turns out to require significant
  restructuring.  That work is well underway, but is not suitable for rc/stable. ]

Signed-off-by: Jacob Shin <jacob.shin@amd.com>
Link: http://lkml.kernel.org/r/1319145326-13902-1-git-send-email-jacob.shin@amd.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index cf0ef986cb6dff51348c17c691491f6f48c61a60..0d403aaf0b35f3ac2fbc1c0faa7b371dc92bd301 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -937,8 +937,21 @@ void __init setup_arch(char **cmdline_p)
 
 #ifdef CONFIG_X86_64
        if (max_pfn > max_low_pfn) {
-               max_pfn_mapped = init_memory_mapping(1UL<<32,
-                                                    max_pfn<<PAGE_SHIFT);
+               int i;
+               for (i = 0; i < e820.nr_map; i++) {
+                       struct e820entry *ei = &e820.map[i];
+
+                       if (ei->addr + ei->size <= 1UL << 32)
+                               continue;
+
+                       if (ei->type == E820_RESERVED)
+                               continue;
+
+                       max_pfn_mapped = init_memory_mapping(
+                               ei->addr < 1UL << 32 ? 1UL << 32 : ei->addr,
+                               ei->addr + ei->size);
+               }
+
                /* can we preseve max_low_pfn ?*/
                max_low_pfn = max_pfn;
        }