Messages in this thread Patch in this message | | | From | Alexey Neyman <> | Subject | [PATCH] Fix coalescing host bridge windows in arch/x86/pci/acpi.c | Date | Sun, 22 Sep 2013 23:15:46 -0700 |
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[Resending due to no response to the original message in a week]
Hi all,
I have a board with a BIOS bug that reports the following I/O port regions in _CRS on one of the host bridges:
0x0000-0x03af // #0 0x03e0-0x0cf7 // #1 0x03b0-0x03bb // #2 0x03c0-0x03df // #3 0x0000-0xdfff // #4 0xf000-0xffff // #5
Obviously, region number #4 is erroneous as it overlaps with regions #0..3. The code in coalesce_windows() in arch/x86/pci/acpi.c attempts to recover from such kind of BIOS bugs by merging the overlapping regions. Current code expands region #0 to 0x0000-0xdffff and makes region #4 ignored. As a result, overlap of the expanded region #0 with regions #1..3 remains undetected (as the inner loop already compared them with region #0). As a result, regions #1..3 are inserted into the resource tree even though they overlap with adjusted region #0 - which later results in resource conflicts for PCI devices with IO ports in one of those regions (e.g., for an PCI IDE controller in legacy mode - which has port 0x3f6). The kernel then refuses to initialize these devices.
The fix: instead of expanding res1 and ignoring res2, do the opposite. The res2 window is yet to be compared against all windows between res1 and res2 (regions #1..3 in the above example), so the resulting resource map will include just the expanded region - and will ignore any overlapping ones.
Signed-off-by: Alexey Neyman <stilor@att.net>diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c index b30e937..7fb24e5 100644 --- a/arch/x86/pci/acpi.c +++ b/arch/x86/pci/acpi.c @@ -354,12 +354,12 @@ static void coalesce_windows(struct pci_root_info *info, unsigned long type) * the kernel resource tree doesn't allow overlaps. */ if (resource_overlaps(res1, res2)) { - res1->start = min(res1->start, res2->start); - res1->end = max(res1->end, res2->end); + res2->start = min(res1->start, res2->start); + res2->end = max(res1->end, res2->end); dev_info(&info->bridge->dev, "host bridge window expanded to %pR; %pR ignored\n", - res1, res2); - res2->flags = 0; + res2, res1); + res1->flags = 0; } } } | |