[PATCH] i386/x86-64 Correct for broken MCFG tables on K8 systems

They report all busses as MMCONFIG capable, but it never works for the
internal devices in the CPU's builtin northbridge.

It just probes all func 0 devices on bus 0 (the internal northbridge is
currently always on bus 0) and if they are not accessible using MCFG they are
put into a special fallback bitmap.

On systems where it isn't we assume the BIOS vendor supplied correct MCFG.

Requires the earlier patch for mmconfig type1 fallback

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

1 files changed, 42 insertions, 3 deletions

diff --git a/arch/i386/pci/mmconfig.c b/arch/i386/pci/mmconfig.c
index cc787a7c030..08a08490121 100644
--- a/arch/i386/pci/mmconfig.c
+++ b/arch/i386/pci/mmconfig.c
@@ -19,14 +19,20 @@
 /* The base address of the last MMCONFIG device accessed */
 static u32 mmcfg_last_accessed_device;
 
+static DECLARE_BITMAP(fallback_slots, 32);
+
 /*
  * Functions for accessing PCI configuration space with MMCONFIG accesses
  */
-static u32 get_base_addr(unsigned int seg, int bus)
+static u32 get_base_addr(unsigned int seg, int bus, unsigned devfn)
 {
 	int cfg_num = -1;
 	struct acpi_table_mcfg_config *cfg;
 
+	if (seg == 0 && bus == 0 &&
+	    test_bit(PCI_SLOT(devfn), fallback_slots))
+		return 0;
+
 	while (1) {
 		++cfg_num;
 		if (cfg_num >= pci_mmcfg_config_num) {
@@ -60,7 +66,7 @@ static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
 	if (!value || (bus > 255) || (devfn > 255) || (reg > 4095))
 		return -EINVAL;
 
-	base = get_base_addr(seg, bus);
+	base = get_base_addr(seg, bus, devfn);
 	if (!base)
 		return pci_conf1_read(seg,bus,devfn,reg,len,value);
 
@@ -94,7 +100,7 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
 	if ((bus > 255) || (devfn > 255) || (reg > 4095)) 
 		return -EINVAL;
 
-	base = get_base_addr(seg, bus);
+	base = get_base_addr(seg, bus, devfn);
 	if (!base)
 		return pci_conf1_write(seg,bus,devfn,reg,len,value);
 
@@ -124,6 +130,37 @@ 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;
+	unsigned long flags;
+
+	for (i = 0; i < 32; i++) {
+		u32 val1;
+		u32 addr;
+
+		pci_conf1_read(0, 0, PCI_DEVFN(i, 0), 0, 4, &val1);
+		if (val1 == 0xffffffff)
+			continue;
+
+		/* Locking probably not needed, but safer */
+		spin_lock_irqsave(&pci_config_lock, flags);
+		addr = get_base_addr(0, 0, PCI_DEVFN(i, 0));
+		if (addr != 0)
+			pci_exp_set_dev_base(addr, 0, PCI_DEVFN(i, 0));
+		if (addr == 0 || readl((u32 *)addr) != val1)
+			set_bit(i, fallback_slots);
+		spin_unlock_irqrestore(&pci_config_lock, flags);
+	}
+}
+
 static int __init pci_mmcfg_init(void)
 {
 	if ((pci_probe & PCI_PROBE_MMCONF) == 0)
@@ -139,6 +176,8 @@ static int __init pci_mmcfg_init(void)
 	raw_pci_ops = &pci_mmcfg;
 	pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;
 
+	unreachable_devices();
+
  out:
 	return 0;
 }