From: Jacob Shin <jacob.shin@amd.com>
Date: Thu, 20 Oct 2011 21:15:26 +0000 (-0500)
Subject: x86: Exclude E820_RESERVED regions and memory holes above 4 GB from direct mapping.
X-Git-Tag: v3.4.16~30
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=efd5fa0c1a1d1b46846ea6e8d1a783d0d8a6a721;p=karo-tx-linux.git

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 1a2901562059..fbbd1eb6c68e 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -927,8 +927,21 @@ 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;
 	}