Commit 6ac665c63dca ("PCI: rewrite PCI BAR reading code") altered
__pci_read_base's local variable 'l', masking off its lower non-addressing
related bits, prior to it being passed in as the 'base' parameter to
pci_size(). This masking broke pci_size's r/o BAR detection logic's
comparison check for r/o BARs that have lower order bits set. For such
occurrences, the 'base == maxbase' check will no longer ever be "true".
This patch resolves this issue by also masking off the non-addressing
related bits of 'sz' before passing it into pci_size() as the 'maxbase'
parameter. With this change the r/o detection logic of pci_size() will
once again catch known occurrences that have been encountered to date:
- AGP aperture BAR of AMD-7xx host bridges; if the AGP window
disabled, this BAR is read-only and read as 0x00000008 [1]
- BAR0-4 of ALi IDE controllers can be non-zero and read-only [1]
- Intel Sandy Bridge - Thermal Management Controller [8086:0103];
BAR 0 returning 0xfed98004 [2]
- Intel Xeon E5 v3/Core i7 Power Control Unit [8086:2fc0];
Bar 0 returning 0x00001a [3]
[1] From Thomas Gleixner's "Linux kernel history" repository:
https://git.kernel.org/cgit/linux/kernel/git/tglx/history.git/commit/drivers/pci/probe.c?id=1307ef6621991f1c4bc3cec1b5a4ebd6fd3d66b9
pre-git commit 1307ef662199 "PCI: probing read-only Bars"
[2] https://bugzilla.kernel.org/show_bug.cgi?id=43331
[3] https://bugzilla.kernel.org/show_bug.cgi?id=85991
Reported-by: William Unruh <unruh@xxxxxxxxxxxxxx>
Reported-by: Martin Lucina <martin@xxxxxxxxxx>
Signed-off-by: Myron Stowe <myron.stowe@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
---
drivers/pci/probe.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 5ed9930..19dc247 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -216,14 +216,17 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
res->flags |= IORESOURCE_SIZEALIGN;
if (res->flags & IORESOURCE_IO) {
l &= PCI_BASE_ADDRESS_IO_MASK;
+ sz &= PCI_BASE_ADDRESS_IO_MASK;
mask = PCI_BASE_ADDRESS_IO_MASK & (u32) IO_SPACE_LIMIT;
} else {
l &= PCI_BASE_ADDRESS_MEM_MASK;
+ sz &= PCI_BASE_ADDRESS_MEM_MASK;
mask = (u32)PCI_BASE_ADDRESS_MEM_MASK;
}
} else {
res->flags |= (l & IORESOURCE_ROM_ENABLE);
l &= PCI_ROM_ADDRESS_MASK;
+ sz &= PCI_ROM_ADDRESS_MASK;
mask = (u32)PCI_ROM_ADDRESS_MASK;
}
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