Messages in this thread Patch in this message | | | From | Alexey Neyman <> | Subject | Re: [PATCH] Fix coalescing host bridge windows in arch/x86/pci/acpi.c | Date | Sat, 28 Sep 2013 00:12:48 -0700 |
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On Tuesday, September 24, 2013 11:47:21 AM Yijing Wang wrote: > On 2013/9/23 14:15, Alexey Neyman wrote: > > [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> > > It looks fine to me, but I have no platform to test it. :)
Thanks for a review. Could anybody push it into the tree? :) For convenience, patch attached again.
Regards, Alexey.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; } } } | |