x86/PCI: make sure _PAGE_IOMAP it set on pci mappings

When mapping pci space via /sys or /proc, make sure we're really
doing a hardware mapping by setting _PAGE_IOMAP.

[ Impact: bugfix; make PCI mappings map the right pages ]
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: "H. Peter Anvin" <hpa@zytor.com>
Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: x86@kernel.org

arch/x86/pci/i386.c

@@ -311,6 +311,8 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 		 */
 		prot |= _PAGE_CACHE_UC_MINUS;
 
+	prot |= _PAGE_IOMAP;	/* creating a mapping for IO */
+
 	vma->vm_page_prot = __pgprot(prot);
 
 	if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,