As per the specification, the base address reported by ACPI is the one that would be used if the region started at bus 0. Hence the start_bus_number offset needs to be added not only to the virtual address, but also the physical one when establishing the mapping, and it then needs to be subtracted when obtaining the virtual address for doing accesses. Signed-off-by: Jan Beulich --- a/xen/arch/x86/x86_64/mmconfig_64.c +++ b/xen/arch/x86/x86_64/mmconfig_64.c @@ -25,7 +25,7 @@ struct mmcfg_virt { static struct mmcfg_virt *pci_mmcfg_virt; static int __initdata mmcfg_pci_segment_shift; -static char __iomem *get_virt(unsigned int seg, unsigned bus) +static char __iomem *get_virt(unsigned int seg, unsigned int *bus) { struct acpi_mcfg_allocation *cfg; int cfg_num; @@ -33,9 +33,11 @@ static char __iomem *get_virt(unsigned i for (cfg_num = 0; cfg_num < pci_mmcfg_config_num; cfg_num++) { cfg = pci_mmcfg_virt[cfg_num].cfg; if (cfg->pci_segment == seg && - (cfg->start_bus_number <= bus) && - (cfg->end_bus_number >= bus)) + (cfg->start_bus_number <= *bus) && + (cfg->end_bus_number >= *bus)) { + *bus -= cfg->start_bus_number; return pci_mmcfg_virt[cfg_num].virt; + } } /* Fall back to type 0 */ @@ -46,7 +48,7 @@ static char __iomem *pci_dev_base(unsign { char __iomem *addr; - addr = get_virt(seg, bus); + addr = get_virt(seg, &bus); if (!addr) return NULL; return addr + ((bus << 20) | (devfn << 12)); @@ -121,8 +123,11 @@ static void __iomem * __init mcfg_iorema if (virt + size < virt || virt + size > PCI_MCFG_VIRT_END) return NULL; - map_pages_to_xen(virt, cfg->address >> PAGE_SHIFT, - size >> PAGE_SHIFT, PAGE_HYPERVISOR_NOCACHE); + if (map_pages_to_xen(virt, + (cfg->address >> PAGE_SHIFT) + + (cfg->start_bus_number << (20 - PAGE_SHIFT)), + size >> PAGE_SHIFT, PAGE_HYPERVISOR_NOCACHE)) + return NULL; return (void __iomem *) virt; }