1 files changed, 34 insertions, 2 deletions

diff --git a/arch/x86_64/pci/mmconfig.c b/arch/x86_64/pci/mmconfig.c
index 22ff1b07d4e0..9c4f907e301c 100644
--- a/arch/x86_64/pci/mmconfig.c
+++ b/arch/x86_64/pci/mmconfig.c
@@ -8,10 +8,13 @@
 #include <linux/pci.h>
 #include <linux/init.h>
 #include <linux/acpi.h>
+#include <linux/bitmap.h>
 #include "pci.h"
 
 #define MMCONFIG_APER_SIZE (256*1024*1024)
 
+static DECLARE_BITMAP(fallback_slots, 32);
+
 /* Static virtual mapping of the MMCONFIG aperture */
 struct mmcfg_virt {
         struct acpi_table_mcfg_config *cfg;
@@ -40,9 +43,12 @@ static char *get_virt(unsigned int seg, unsigned bus)
         }
 }
 
-static inline char *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
+static char *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
 {
-        char *addr = get_virt(seg, bus);
+        char *addr;
+        if (seg == 0 && bus == 0 && test_bit(PCI_SLOT(devfn), &fallback_slots))
+                return NULL;
+        addr = get_virt(seg, bus);
         if (!addr)
                 return NULL;
         return addr + ((bus << 20) | (devfn << 12));
@@ -109,6 +115,30 @@ static struct pci_raw_ops pci_mmcfg = {
         .write =        pci_mmcfg_write,
 };
 
+/* K8 systems have some devices (typically in the builtin northbridge)
+   that are only accessible using type1
+   Normally this can be expressed in the MCFG by not listing them
+   and assigning suitable _SEGs, but this isn't implemented in some BIOS.
+   Instead try to discover all devices on bus 0 that are unreachable using MM
+   and fallback for them.
+   We only do this for bus 0/seg 0 */
+static __init void unreachable_devices(void)
+{
+        int i;
+        for (i = 0; i < 32; i++) {
+                u32 val1;
+                char *addr;
+
+                pci_conf1_read(0, 0, PCI_DEVFN(i,0), 0, 4, &val1);
+                if (val1 == 0xffffffff)
+                        continue;
+                addr = pci_dev_base(0, 0, PCI_DEVFN(i, 0));
+                if (addr == NULL|| readl(addr) != val1) {
+                        set_bit(i, &fallback_slots);
+                }
+        }
+}
+
 static int __init pci_mmcfg_init(void)
 {
         int i;
@@ -139,6 +169,8 @@ static int __init pci_mmcfg_init(void)
                 printk(KERN_INFO "PCI: Using MMCONFIG at %x\n", pci_mmcfg_config[i].base_address);
         }
 
+        unreachable_devices();
+
         raw_pci_ops = &pci_mmcfg;
         pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;