[patch 36/45] x86, PAT, PCI: Change vma prot in pci_mmap to reflect inherited prot

[Chris Wright]

-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>

upstream commit: 9cdec049389ce2c324fd1ec508a71528a27d4a07

While looking at the issue in the thread:

  http://marc.info/?l=dri-devel&m=123606627824556&w=2

noticed a bug in pci PAT code and memory type setting.

PCI mmap code did not set the proper protection in vma, when it
inherited protection in reserve_memtype. This bug only affects
the case where there exists a WC mapping before X does an mmap
with /proc or /sys pci interface. This will cause X userlevel
mmap from /proc or /sysfs to fail on fork.

Reported-by: Kevin Winchester <kjwinchester@xxxxxxxxx>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
Cc: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
LKML-Reference: <20090323190720.GA16831@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
 arch/x86/pci/i386.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -319,6 +319,9 @@ int pci_mmap_page_range(struct pci_dev *
 			return -EINVAL;
 		}
 		flags = new_flags;
+		vma->vm_page_prot = __pgprot(
+			(pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK) |
+			flags);
 	}
 
 	if (((vma->vm_pgoff < max_low_pfn_mapped) ||

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