x86: add pci=check_enable_amd_mmconf and dmi check

so will disable that feature by default, and only enable that via
pci=check_enable_amd_mmconf or for system match with dmi table.

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

3 files changed, 8 insertions, 0 deletions

diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 07d53184f7a4..2a4d751818b7 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -425,6 +425,10 @@ char * __devinit  pcibios_setup(char *str)
                 pci_probe &= ~PCI_PROBE_MMCONF;
                 return NULL;
         }
+        else if (!strcmp(str, "check_enable_amd_mmconf")) {
+                pci_probe |= PCI_CHECK_ENABLE_AMD_MMCONF;
+                return NULL;
+        }
 #endif
         else if (!strcmp(str, "noacpi")) {
                 acpi_noirq_set();
diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index bdf62243186a..0cfebecf2a8f 100644
--- a/arch/x86/pci/mmconfig-shared.c
+++ b/arch/x86/pci/mmconfig-shared.c
@@ -107,6 +107,9 @@ static const char __init *pci_mmcfg_amd_fam10h(void)
         int i;
         unsigned segnbits = 0, busnbits;
 
+        if (!(pci_probe & PCI_CHECK_ENABLE_AMD_MMCONF))
+                return NULL;
+
         address = MSR_FAM10H_MMIO_CONF_BASE;
         if (rdmsr_safe(address, &low, &high))
                 return NULL;
diff --git a/arch/x86/pci/pci.h b/arch/x86/pci/pci.h
index c8b89a832c66..8ef86b5c37c8 100644
--- a/arch/x86/pci/pci.h
+++ b/arch/x86/pci/pci.h
@@ -26,6 +26,7 @@
 #define PCI_ASSIGN_ALL_BUSSES   0x4000
 #define PCI_CAN_SKIP_ISA_ALIGN  0x8000
 #define PCI_USE__CRS            0x10000
+#define PCI_CHECK_ENABLE_AMD_MMCONF     0x20000
 
 extern unsigned int pci_probe;
 extern unsigned long pirq_table_addr;