intel-iommu: PAE memory corruption fix

PAGE_MASK is 0xFFFFF000 on i386 -- even with PAE.

So it's not sufficient to ensure that you use phys_addr_t or uint64_t
everywhere you handle physical addresses -- you also have to avoid using
the construct 'addr & PAGE_MASK', because that will strip the high 32
bits of the address.

This patch avoids that problem by using PHYSICAL_PAGE_MASK instead of
PAGE_MASK where appropriate. It leaves '& PAGE_MASK' in a few instances
that don't matter -- where it's being used on the virtual bus addresses
we're dishing out, which are 32-bit anyway.

Since PHYSICAL_PAGE_MASK is not present on other architectures, we have
to define it (to PAGE_MASK) if it's not already defined.

Maybe it would be better just to fix PAGE_MASK for i386/PAE?

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 001b328adf8..a563fbe559d 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -59,6 +59,10 @@
 #define DMA_32BIT_PFN           IOVA_PFN(DMA_BIT_MASK(32))
 #define DMA_64BIT_PFN           IOVA_PFN(DMA_BIT_MASK(64))
 
+#ifndef PHYSICAL_PAGE_MASK
+#define PHYSICAL_PAGE_MASK PAGE_MASK
+#endif
+
 /* global iommu list, set NULL for ignored DMAR units */
 static struct intel_iommu **g_iommus;
 
@@ -1216,7 +1220,7 @@ static void dmar_init_reserved_ranges(void)
                         if (!r->flags || !(r->flags & IORESOURCE_MEM))
                                 continue;
                         addr = r->start;
-                        addr &= PAGE_MASK;
+                        addr &= PHYSICAL_PAGE_MASK;
                         size = r->end - addr;
                         size = PAGE_ALIGN(size);
                         iova = reserve_iova(&reserved_iova_list, IOVA_PFN(addr),
@@ -2173,7 +2177,8 @@ static dma_addr_t __intel_map_single(struct device *hwdev, phys_addr_t paddr,
          * is not a big problem
          */
         ret = domain_page_mapping(domain, start_paddr,
-                ((u64)paddr) & PAGE_MASK, size, prot);
+                                  ((u64)paddr) & PHYSICAL_PAGE_MASK,
+                                  size, prot);
         if (ret)
                 goto error;
 
@@ -2463,8 +2468,8 @@ static int intel_map_sg(struct device *hwdev, struct scatterlist *sglist, int ne
                 addr = page_to_phys(sg_page(sg)) + sg->offset;
                 size = aligned_size((u64)addr, sg->length);
                 ret = domain_page_mapping(domain, start_addr + offset,
-                        ((u64)addr) & PAGE_MASK,
-                        size, prot);
+                                          ((u64)addr) & PHYSICAL_PAGE_MASK,
+                                          size, prot);
                 if (ret) {
                         /*  clear the page */
                         dma_pte_clear_range(domain, start_addr,