[PATCH] i386/x86-64: Check that MCFG points to an e820 reserved area
This patch introduces a user for the e820_all_mapped function:
There have been several machines that don't have a working MMCONFIG,
often because of a buggy MCFG table in the ACPI bios. This patch adds a
simple sanity check that detects a whole bunch of these cases, and when
it detects it, linux now boots rather than crash-and-burns.
The accuracy of this detection can in principle be improved if there was
a "is this entire range in e820 with THIS attribute", but no such
function exist and the complexity needed for this is not really worth
it; this simple check already catches most cases anyway.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/pci/mmconfig.c b/arch/i386/pci/mmconfig.c
index 6137890..ee815c7 100644
--- a/arch/i386/pci/mmconfig.c
+++ b/arch/i386/pci/mmconfig.c
@@ -12,8 +12,11 @@
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/acpi.h>
+#include <asm/e820.h>
#include "pci.h"
+#define MMCONFIG_APER_SIZE (256*1024*1024)
+
#define mmcfg_virt_addr ((void __iomem *) fix_to_virt(FIX_PCIE_MCFG))
/* The base address of the last MMCONFIG device accessed */
@@ -183,6 +186,14 @@
(pci_mmcfg_config[0].base_address == 0))
return;
+ if (!e820_all_mapped(pci_mmcfg_config[0].base_address,
+ pci_mmcfg_config[0].base_address + MMCONFIG_APER_SIZE,
+ E820_RESERVED)) {
+ printk(KERN_ERR "PCI: BIOS Bug: MCFG area is not E820-reserved\n");
+ printk(KERN_ERR "PCI: Not using MMCONFIG.\n");
+ return;
+ }
+
printk(KERN_INFO "PCI: Using MMCONFIG\n");
raw_pci_ops = &pci_mmcfg;
pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;