PCI: avoid P2P prefetch window for expansion ROMs

Avoid creating P2P prefetch window for expansion ROMs

Because of the future possibility that P2P prefetch windows will contain
address ranges above 4GB some BIOSes are providing space in the P2P
non-prefetch windows for expansion ROMs.  This is due to expansion ROM
BAR 32-bit limitation.  When expansion ROM BARs without BIOS assigned
address(es) are currently found behind a P2P bridge, the kernel attempts
to create a P2P prefetch window for them even though space for them has
already been provided in the non-prefetch window.  _CRS on some systems
with certain resource conservation conscious BIOSes may not provide the
extra 1MB or more memory resource needed for the expansion ROM motivated
prefetch window causing resource allocation errors.

This change corrects the problem by removing IORESOURCE_PREFETCH from
the expansion ROM flags initialization.  It also removes
IORESOURCE_CACHEABLE which seems inappropriate if only non-cacheable
memory is available.

Signed-off-by: Gary Hade <gary.hade@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 59d6c30..3112024 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -276,8 +276,7 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
                        sz = pci_size(l, sz, (u32)PCI_ROM_ADDRESS_MASK);
                        if (sz) {
                                res->flags = (l & IORESOURCE_ROM_ENABLE) |
-                                 IORESOURCE_MEM | IORESOURCE_PREFETCH |
-                                 IORESOURCE_READONLY | IORESOURCE_CACHEABLE;
+                                 IORESOURCE_MEM | IORESOURCE_READONLY;
                                res->start = l & PCI_ROM_ADDRESS_MASK;
                                res->end = res->start + (unsigned long) sz;
                        }