From: OGAWA Hirofumi Currently, unreachable_devices() compares value of mmconfig and value of conf1. But it doesn't check the device is reachable or not. Signed-off-by: OGAWA Hirofumi Cc: Arjan van de Ven Cc: Andi Kleen Signed-off-by: Andrew Morton --- arch/i386/pci/mmconfig-shared.c | 12 +++++++----- arch/i386/pci/mmconfig.c | 6 ++++++ arch/i386/pci/pci.h | 2 ++ arch/x86_64/pci/mmconfig.c | 6 ++++++ 4 files changed, 21 insertions(+), 5 deletions(-) diff -puN arch/i386/pci/mmconfig-shared.c~mmconfig-fix-unreachable_devices arch/i386/pci/mmconfig-shared.c --- a/arch/i386/pci/mmconfig-shared.c~mmconfig-fix-unreachable_devices +++ a/arch/i386/pci/mmconfig-shared.c @@ -43,12 +43,14 @@ static void __init unreachable_devices(v if (val1 == 0xffffffff) continue; - raw_pci_ops->read(0, bus, devfn, 0, 4, &val2); - if (val1 != val2) { - set_bit(i + 32 * bus, pci_mmcfg_fallback_slots); - printk(KERN_NOTICE "PCI: No mmconfig possible" - " on device %02x:%02x\n", bus, i); + if (pci_mmcfg_arch_reachable(0, bus, devfn)) { + raw_pci_ops->read(0, bus, devfn, 0, 4, &val2); + if (val1 == val2) + continue; } + set_bit(i + 32 * bus, pci_mmcfg_fallback_slots); + printk(KERN_NOTICE "PCI: No mmconfig possible on device" + " %02x:%02x\n", bus, i); } } } diff -puN arch/i386/pci/mmconfig.c~mmconfig-fix-unreachable_devices arch/i386/pci/mmconfig.c --- a/arch/i386/pci/mmconfig.c~mmconfig-fix-unreachable_devices +++ a/arch/i386/pci/mmconfig.c @@ -136,6 +136,12 @@ static struct pci_raw_ops pci_mmcfg = { .write = pci_mmcfg_write, }; +int __init pci_mmcfg_arch_reachable(unsigned int seg, unsigned int bus, + unsigned int devfn) +{ + return get_base_addr(seg, bus, devfn) != 0; +} + int __init pci_mmcfg_arch_init(void) { printk(KERN_INFO "PCI: Using MMCONFIG\n"); diff -puN arch/i386/pci/pci.h~mmconfig-fix-unreachable_devices arch/i386/pci/pci.h --- a/arch/i386/pci/pci.h~mmconfig-fix-unreachable_devices +++ a/arch/i386/pci/pci.h @@ -101,4 +101,6 @@ extern void pcibios_sort(void); #define PCI_MMCFG_MAX_CHECK_BUS 16 extern DECLARE_BITMAP(pci_mmcfg_fallback_slots, 32*PCI_MMCFG_MAX_CHECK_BUS); +extern int __init pci_mmcfg_arch_reachable(unsigned int seg, unsigned int bus, + unsigned int devfn); extern int __init pci_mmcfg_arch_init(void); diff -puN arch/x86_64/pci/mmconfig.c~mmconfig-fix-unreachable_devices arch/x86_64/pci/mmconfig.c --- a/arch/x86_64/pci/mmconfig.c~mmconfig-fix-unreachable_devices +++ a/arch/x86_64/pci/mmconfig.c @@ -112,6 +112,12 @@ static struct pci_raw_ops pci_mmcfg = { .write = pci_mmcfg_write, }; +int __init pci_mmcfg_arch_reachable(unsigned int seg, unsigned int bus, + unsigned int devfn) +{ + return pci_dev_base(seg, bus, devfn) != NULL; +} + int __init pci_mmcfg_arch_init(void) { int i; _