x86, PAT, PCI: Change vma prot in pci_mmap to reflect inherited prot

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@gmail.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Dave Airlie <airlied@redhat.com>
Cc: <stable@kernel.org>
LKML-Reference: <20090323190720.GA16831@linux-os.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index 5ead808dd70..f234a37bd42 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -319,6 +319,9 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
                         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) ||