1 files changed, 15 insertions, 8 deletions

diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c
index 185d3cc9129b..5e269a5dde2e 100644
--- a/arch/x86/kernel/setup_64.c
+++ b/arch/x86/kernel/setup_64.c
@@ -751,14 +751,21 @@ static void __cpuinit fam10h_check_enable_mmcfg(struct cpuinfo_x86 *c)
 
         /* try to make sure that AP's setting is identical to BSP setting */
         if (val & FAM10H_MMIO_CONF_ENABLE) {
-                u64 base;
-                base = val & (0xffffULL << 32);
-                if (fam10h_pci_mmconf_base_status <= 0) {
-                        fam10h_pci_mmconf_base = base;
-                        fam10h_pci_mmconf_base_status = 1;
-                        return;
-                } else if (fam10h_pci_mmconf_base ==  base)
-                        return;
+                unsigned busnbits;
+                busnbits = (val >> FAM10H_MMIO_CONF_BUSRANGE_SHIFT) &
+                        FAM10H_MMIO_CONF_BUSRANGE_MASK;
+
+                /* only trust the one handle 256 buses, if acpi=off */
+                if (!acpi_pci_disabled || busnbits >= 8) {
+                        u64 base;
+                        base = val & (0xffffULL << 32);
+                        if (fam10h_pci_mmconf_base_status <= 0) {
+                                fam10h_pci_mmconf_base = base;
+                                fam10h_pci_mmconf_base_status = 1;
+                                return;
+                        } else if (fam10h_pci_mmconf_base ==  base)
+                                return;
+                }
         }
 
         /*