x86-64/MMCFG: correct base address computation for regions not starting at bus 0

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 <jbeulich@novell.com>

diff --git a/xen/arch/x86/x86_64/mmconfig_64.c b/xen/arch/x86/x86_64/mmconfig_64.c
index c17acf9ef961dd32f1ba28fdb0d412ee94206b7e..3f1b841b3480986916fd781ba1e4dd49d2ed0891 100644 (file)
--- 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 int seg, unsigned bus)
     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(unsigned int seg, unsigned int bus, unsigned i
 {
     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_ioremap(struct acpi_mcfg_allocation *cfg)
     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;
 }