[PATCH] x86: Allow disabling early pci scans with pci=noearly or disallowing conf1

Some buggy systems can machine check when config space accesses
happen for some non existent devices.  i386/x86-64 do some early
device scans that might trigger this. Allow pci=noearly to disable
this. Also when type 1 is disabling also don't do any early
accesses which are always type1.

This moves the pci= configuration parsing to be a early parameter.
I don't think this can break anything because it only changes
a single global that is only used by PCI.

Cc: gregkh@suse.de
Cc: Trammell Hudson <hudson@osresearch.net>

Signed-off-by: Andi Kleen <ak@suse.de>

12 files changed, 41 insertions, 6 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 71d05f481727..4ae99f6e9938 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1240,7 +1240,11 @@ running once the system is up.
                                 bootloader. This is currently used on
                                 IXP2000 systems where the bus has to be
                                 configured a certain way for adjunct CPUs.
-
+                noearly         [X86] Don't do any early type 1 scanning.
+                                This might help on some broken boards which
+                                machine check when some devices' config space
+                                is read. But various workarounds are disabled
+                                and some IOMMU drivers will not work.
         pcmv=           [HW,PCMCIA] BadgePAD 4
 
         pd.             [PARIDE]
diff --git a/arch/i386/kernel/acpi/earlyquirk.c b/arch/i386/kernel/acpi/earlyquirk.c
index 1649a175a206..fe799b11ac0a 100644
--- a/arch/i386/kernel/acpi/earlyquirk.c
+++ b/arch/i386/kernel/acpi/earlyquirk.c
@@ -48,7 +48,11 @@ void __init check_acpi_pci(void)
         int num, slot, func;
 
         /* Assume the machine supports type 1. If not it will 
-           always read ffffffff and should not have any side effect. */
+           always read ffffffff and should not have any side effect.
+           Actually a few buggy systems can machine check. Allow the user
+           to disable it by command line option at least -AK */
+        if (!early_pci_allowed())
+                return;
 
         /* Poor man's PCI discovery */
         for (num = 0; num < 32; num++) {
diff --git a/arch/i386/pci/common.c b/arch/i386/pci/common.c
index 0a362e3aeac5..68bce194e688 100644
--- a/arch/i386/pci/common.c
+++ b/arch/i386/pci/common.c
@@ -242,6 +242,10 @@ char * __devinit  pcibios_setup(char *str)
                 acpi_noirq_set();
                 return NULL;
         }
+        else if (!strcmp(str, "noearly")) {
+                pci_probe |= PCI_PROBE_NOEARLY;
+                return NULL;
+        }
 #ifndef CONFIG_X86_VISWS
         else if (!strcmp(str, "usepirqmask")) {
                 pci_probe |= PCI_USE_PIRQ_MASK;
diff --git a/arch/i386/pci/early.c b/arch/i386/pci/early.c
index b1f7f40d809b..713d6c866cae 100644
--- a/arch/i386/pci/early.c
+++ b/arch/i386/pci/early.c
@@ -1,6 +1,8 @@
 #include <linux/kernel.h>
+#include <linux/pci.h>
 #include <asm/pci-direct.h>
 #include <asm/io.h>
+#include "pci.h"
 
 /* Direct PCI access. This is used for PCI accesses in early boot before
    the PCI subsystem works. */
@@ -42,3 +44,9 @@ void write_pci_config(u8 bus, u8 slot, u8 func, u8 offset,
         outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
         outl(val, 0xcfc);
 }
+
+int early_pci_allowed(void)
+{
+        return (pci_probe & (PCI_PROBE_CONF1|PCI_PROBE_NOEARLY)) ==
+                        PCI_PROBE_CONF1;
+}
diff --git a/arch/i386/pci/pci.h b/arch/i386/pci/pci.h
index 8a7cf1f23684..1814f74569c6 100644
--- a/arch/i386/pci/pci.h
+++ b/arch/i386/pci/pci.h
@@ -17,6 +17,7 @@
 #define PCI_PROBE_CONF2         0x0004
 #define PCI_PROBE_MMCONF        0x0008
 #define PCI_PROBE_MASK          0x000f
+#define PCI_PROBE_NOEARLY       0x0010
 
 #define PCI_NO_SORT             0x0100
 #define PCI_BIOS_SORT           0x0200
diff --git a/arch/x86_64/kernel/aperture.c b/arch/x86_64/kernel/aperture.c
index f851e1f9c82a..b487396c4c5b 100644
--- a/arch/x86_64/kernel/aperture.c
+++ b/arch/x86_64/kernel/aperture.c
@@ -212,7 +212,7 @@ void __init iommu_hole_init(void)
         u64 aper_base, last_aper_base = 0;
         int valid_agp = 0;
 
-        if (iommu_aperture_disabled || !fix_aperture)
+        if (iommu_aperture_disabled || !fix_aperture || !early_pci_allowed())
                 return;
 
         printk("Checking aperture...\n"); 
diff --git a/arch/x86_64/kernel/early-quirks.c b/arch/x86_64/kernel/early-quirks.c
index d637cff1c4b1..208e38a372c1 100644
--- a/arch/x86_64/kernel/early-quirks.c
+++ b/arch/x86_64/kernel/early-quirks.c
@@ -82,6 +82,10 @@ static struct chipset early_qrk[] = {
 void __init early_quirks(void)
 {
         int num, slot, func;
+
+        if (!early_pci_allowed())
+                return;
+
         /* Poor man's PCI discovery */
         for (num = 0; num < 32; num++) {
                 for (slot = 0; slot < 32; slot++) {
diff --git a/arch/x86_64/kernel/pci-calgary.c b/arch/x86_64/kernel/pci-calgary.c
index 466588f95601..cfb09b07ae99 100644
--- a/arch/x86_64/kernel/pci-calgary.c
+++ b/arch/x86_64/kernel/pci-calgary.c
@@ -924,6 +924,9 @@ void __init detect_calgary(void)
         if (swiotlb || no_iommu || iommu_detected)
                 return;
 
+        if (!early_pci_allowed())
+                return;
+
         specified_table_size = determine_tce_table_size(end_pfn * PAGE_SIZE);
 
         for (bus = 0; bus < MAX_PHB_BUS_NUM; bus++) {
diff --git a/arch/x86_64/kernel/vsmp.c b/arch/x86_64/kernel/vsmp.c
index 92f70c74965f..044e852bd25e 100644
--- a/arch/x86_64/kernel/vsmp.c
+++ b/arch/x86_64/kernel/vsmp.c
@@ -20,6 +20,9 @@ static int __init vsmp_init(void)
         void *address;
         unsigned int cap, ctl;
 
+        if (!early_pci_allowed())
+                return 0;
+
         /* Check if we are running on a ScaleMP vSMP box */
         if ((read_pci_config_16(0, 0x1f, 0, PCI_VENDOR_ID) != PCI_VENDOR_ID_SCALEMP) ||
             (read_pci_config_16(0, 0x1f, 0, PCI_DEVICE_ID) != PCI_DEVICE_ID_SCALEMP_VSMP_CTL))
diff --git a/arch/x86_64/mm/k8topology.c b/arch/x86_64/mm/k8topology.c
index 7c45c2d2b8b2..5cf594f9230d 100644
--- a/arch/x86_64/mm/k8topology.c
+++ b/arch/x86_64/mm/k8topology.c
@@ -54,6 +54,9 @@ int __init k8_scan_nodes(unsigned long start, unsigned long end)
 
         nodes_clear(nodes_parsed);
 
+        if (!early_pci_allowed())
+                return -1;
+
         nb = find_northbridge(); 
         if (nb < 0) 
                 return nb;
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 9f79dd6d51ab..684deb6b03aa 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -953,13 +953,12 @@ static int __devinit pci_setup(char *str)
                 }
                 str = k;
         }
-        return 1;
+        return 0;
 }
+early_param("pci", pci_setup);
 
 device_initcall(pci_init);
 
-__setup("pci=", pci_setup);
-
 #if defined(CONFIG_ISA) || defined(CONFIG_EISA)
 /* FIXME: Some boxes have multiple ISA bridges! */
 struct pci_dev *isa_bridge;
diff --git a/include/asm-x86_64/pci-direct.h b/include/asm-x86_64/pci-direct.h
index 9d916cdaa18e..eba9cb471df3 100644
--- a/include/asm-x86_64/pci-direct.h
+++ b/include/asm-x86_64/pci-direct.h
@@ -11,4 +11,6 @@ extern u8 read_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset);
 extern u16 read_pci_config_16(u8 bus, u8 slot, u8 func, u8 offset);
 extern void write_pci_config(u8 bus, u8 slot, u8 func, u8 offset, u32 val);
 
+extern int early_pci_allowed(void);
+
 #endif