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    Subject[patch 3/4] x86_64/i386: Correct for broken MCFG tables on K8 systems
    From: Andi Kleen <ak@muc.de>

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

    This causes problems - some devices are not visible and on x86-64 the
    IOMMU is not detected, causing boot failures on systems with >3GB of
    RAM. It also breaks AGP.

    Workaround 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: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    arch/i386/pci/mmconfig.c | 45 ++++++++++++++++++++++++++++++++++++++++++---
    arch/x86_64/pci/mmconfig.c | 36 ++++++++++++++++++++++++++++++++++--
    2 files changed, 76 insertions(+), 5 deletions(-)

    --- greg-2.6.orig/arch/x86_64/pci/mmconfig.c
    +++ greg-2.6/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,
    }
    }

    -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;

    --- greg-2.6.orig/arch/i386/pci/mmconfig.c
    +++ greg-2.6/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 s
    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
    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;
    }
    --
    -
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