x86/PCI: truncate _CRS windows with _LEN > _MAX - _MIN + 1

Yanko's GA-MA78GM-S2H (BIOS F11) reports the following resource in a PCI
host bridge _CRS:

    [07] 32-Bit DWORD Address Space Resource
         Min Relocatability : MinFixed
         Max Relocatability : MaxFixed
            Address Minimum : CFF00000  (_MIN)
            Address Maximum : FEBFFFFF  (_MAX)
             Address Length : 3EE10000  (_LEN)

This is invalid per spec (ACPI 4.0, 6.4.3.5) because it's a fixed size,
fixed location descriptor, but _LEN != _MAX - _MIN + 1.

Based on https://bugzilla.kernel.org/show_bug.cgi?id=15480#c15, I think
Windows handles this by truncating the window so it fits between _MIN and
_MAX.  I also verified this by modifying the SeaBIOS DSDT and booting
Windows 2008 R2 with qemu.

This patch makes Linux truncate the window, too, which fixes:
    http://bugzilla.kernel.org/show_bug.cgi?id=15480

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Tested-by: Yanko Kaneti <yaneti@declera.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 12 insertions, 1 deletions

diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index 75ac3f856ea5..e31160216efb 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -123,7 +123,7 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
         acpi_status status;
         unsigned long flags;
         struct resource *root, *conflict;
-        u64 start, end;
+        u64 start, end, max_len;
 
         status = resource_to_addr(acpi_res, &addr);
         if (!ACPI_SUCCESS(status))
@@ -140,6 +140,17 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
         } else
                 return AE_OK;
 
+        max_len = addr.maximum - addr.minimum + 1;
+        if (addr.address_length > max_len) {
+                dev_printk(KERN_DEBUG, &info->bridge->dev,
+                           "host bridge window length %#llx doesn't fit in "
+                           "%#llx-%#llx, trimming\n",
+                           (unsigned long long) addr.address_length,
+                           (unsigned long long) addr.minimum,
+                           (unsigned long long) addr.maximum);
+                addr.address_length = max_len;
+        }
+
         start = addr.minimum + addr.translation_offset;
         end = start + addr.address_length - 1;