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 <[email protected]>
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Suresh Siddha <[email protected]>
Cc: Jesse Barnes <[email protected]>
Cc: Dave Airlie <[email protected]>
Cc: <[email protected]>
LKML-Reference: <20090323190720[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index 5ead808dd70c3ec34dbd34da39600851b9c30619..f234a37bd428c73aa0e8623079bfbe5e06923948 100644 (file)
--- 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) ||