[PATCH] i386/x86_64: Check if MCFG works for the first 16 busses

Previously only the first bus would be checked against Type 1.

Why 16? Checking all would need too much memory and we
can assume that systems with more than 16 busses have better than
average quality BIOS.

This is an additional defense against bad MCFG tables.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 24 insertions, 15 deletions

diff --git a/arch/x86_64/pci/mmconfig.c b/arch/x86_64/pci/mmconfig.c
index dfe84c322552..d4e25f38287d 100644
--- a/arch/x86_64/pci/mmconfig.c
+++ b/arch/x86_64/pci/mmconfig.c
@@ -14,8 +14,11 @@
 #include "pci.h"
 
 #define MMCONFIG_APER_SIZE (256*1024*1024)
+/* Verify the first 16 busses. We assume that systems with more busses
+   get MCFG right. */
+#define MAX_CHECK_BUS 16
 
-static DECLARE_BITMAP(fallback_slots, 32);
+static DECLARE_BITMAP(fallback_slots, 32*MAX_CHECK_BUS);
 
 /* Static virtual mapping of the MMCONFIG aperture */
 struct mmcfg_virt {
@@ -57,7 +60,8 @@ static char __iomem *get_virt(unsigned int seg, unsigned bus)
 static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
 {
         char __iomem *addr;
-        if (seg == 0 && bus == 0 && test_bit(PCI_SLOT(devfn), fallback_slots))
+        if (seg == 0 && bus < MAX_CHECK_BUS &&
+                test_bit(32*bus + PCI_SLOT(devfn), fallback_slots))
                 return NULL;
         addr = get_virt(seg, bus);
         if (!addr)
@@ -131,21 +135,26 @@ static struct pci_raw_ops pci_mmcfg = {
    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 */
+   and fallback for them. */
 static __init void unreachable_devices(void)
 {
-        int i;
-        for (i = 0; i < 32; i++) {
-                u32 val1;
-                char __iomem *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);
+        int i, k;
+        /* Use the max bus number from ACPI here? */
+        for (k = 0; i < MAX_CHECK_BUS; k++) {
+                for (i = 0; i < 32; i++) {
+                        u32 val1;
+                        char __iomem *addr;
+
+                        pci_conf1_read(0, k, PCI_DEVFN(i,0), 0, 4, &val1);
+                        if (val1 == 0xffffffff)
+                                continue;
+                        addr = pci_dev_base(0, k, PCI_DEVFN(i, 0));
+                        if (addr == NULL|| readl(addr) != val1) {
+                                set_bit(i + 32*k, fallback_slots);
+                                printk(KERN_NOTICE
+                                "PCI: No mmconfig possible on device %x:%x\n",
+                                        k, i);
+                        }
                 }
         }
 }