[Xen-changelog] [xen-4.1-testing] x86-64/MMCFG: correct base address computation for regions not starting at bus 0

[Xen patchbot-4.1-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxxxx>
# Date 1346761398 -7200
# Node ID fc9fe622e5e03c6ffc21bec264969f0ca79dc456
# Parent  58d3c21ee4bde73269d6c1cb063b51cebb21ce99
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@xxxxxxxxxx>
xen-unstable changeset: 23747:b07b6fa76656
xen-unstable date: Mon Jul 25 15:42:19 UTC 2011
---


diff -r 58d3c21ee4bd -r fc9fe622e5e0 xen/arch/x86/x86_64/mmconfig_64.c
--- a/xen/arch/x86/x86_64/mmconfig_64.c Tue Sep 04 12:03:35 2012 +0200
+++ b/xen/arch/x86/x86_64/mmconfig_64.c Tue Sep 04 14:23:18 2012 +0200
@@ -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;
 }

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