From e316075b3cada625bfae9a80dcf4ca3776f77db7 Mon Sep 17 00:00:00 2001 From: Myron Stowe Date: Thu, 30 Oct 2014 11:54:37 -0600 Subject: [PATCH 1/1] PCI: Restore detection of read-only BARs commit 36e8164882ca6d3c41cb91e6f09a3ed236841f80 upstream. Commit 6ac665c63dca ("PCI: rewrite PCI BAR reading code") masked off low-order bits from 'l', but not from 'sz'. Both are passed to pci_size(), which compares 'base == maxbase' to check for read-only BARs. The masking of 'l' means that comparison will never be 'true', so the check for read-only BARs no longer works. Resolve this by also masking off the low-order bits of 'sz' before passing it into pci_size() as 'maxbase'. With this change, pci_size() will once again catch the problems that have been encountered to date: - AGP aperture BAR of AMD-7xx host bridges: if the AGP window is disabled, this BAR is read-only and read as 0x00000008 [1] - BARs 0-4 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] Link: [1] https://git.kernel.org/cgit/linux/kernel/git/tglx/history.git/commit/drivers/pci/probe.c?id=1307ef6621991f1c4bc3cec1b5a4ebd6fd3d66b9 ("PCI: probing read-only BARs" (pre-git)) Link: [2] https://bugzilla.kernel.org/show_bug.cgi?id=43331 Link: [3] https://bugzilla.kernel.org/show_bug.cgi?id=85991 Reported-by: William Unruh Reported-by: Martin Lucina Signed-off-by: Myron Stowe Signed-off-by: Bjorn Helgaas CC: Matthew Wilcox Signed-off-by: Ben Hutchings --- drivers/pci/probe.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 900538056468..bc92c4771e57 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -175,14 +175,17 @@ 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; } -- 2.39.2