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PCI: Fix alignment calculation for resource size larger than align

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The commit bc75c8e507 ("PCI: Rewrite bridge window head alignment
function") did not use if (r_size <= align) check from pbus_size_mem() for
the new head alignment bookkeeping structure (aligns2[]). In some
configurations, this can result in producing a gap into the bridge window
which the resource larger than its alignment cannot fill.

The old alignment calculation algorithm was removed by the subsequent
commit 3958bf16e2 ("PCI: Stop over-estimating bridge window size") which
renamed the aligns2[] array leaving only aligns[] array.

Add the if (r_size <= align) check back to avoid this problem.

Fixes: bc75c8e507 ("PCI: Rewrite bridge window head alignment function")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/all/b05a6f14-979d-42c9-924c-d8408cb12ae7@roeck-us.net/
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Xifer <xiferdev@gmail.com>
Link: https://patch.msgid.link/20260324165633.4583-11-ilpo.jarvinen@linux.intel.com
This commit is contained in:
Ilpo Järvinen
2026-03-27 10:19:08 -05:00
committed by Bjorn Helgaas
parent 9036bd0efc
commit 8cb0816673
1 changed files with 8 additions and 1 deletions
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drivers/pci/setup-bus.c
+8 -1
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@@ -1333,7 +1333,14 @@ static void pbus_size_mem(struct pci_bus *bus, struct resource *b_res,
r_size = resource_size(r);
size += max(r_size, align);
aligns[order] += align;
/*
* If resource's size is larger than its alignment,
* some configurations result in an unwanted gap in
* the head space that the larger resource cannot
* fill.
*/
if (r_size <= align)
aligns[order] += align;
if (order > max_order)
max_order = order;
}