iommu sg merging: x86: make pci-gart iommu respect the segment size limits

This patch makes pci-gart iommu respect segment size limits when
merging sg lists.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index 845cbecd68e9..5ee700f0844d 100644
--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c
@@ -416,6 +416,8 @@ gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, int dir)
         struct scatterlist *s, *ps, *start_sg, *sgmap;
         int need = 0, nextneed, i, out, start;
         unsigned long pages = 0;
+        unsigned int seg_size;
+        unsigned int max_seg_size;
 
         if (nents == 0)
                 return 0;
@@ -426,6 +428,8 @@ gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, int dir)
         out = 0;
         start = 0;
         start_sg = sgmap = sg;
+        seg_size = 0;
+        max_seg_size = dma_get_max_seg_size(dev);
         ps = NULL; /* shut up gcc */
         for_each_sg(sg, s, nents, i) {
                 dma_addr_t addr = sg_phys(s);
@@ -443,11 +447,13 @@ gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, int dir)
                          * offset.
                          */
                         if (!iommu_merge || !nextneed || !need || s->offset ||
+                            (s->length + seg_size > max_seg_size) ||
                             (ps->offset + ps->length) % PAGE_SIZE) {
                                 if (dma_map_cont(start_sg, i - start, sgmap,
                                                   pages, need) < 0)
                                         goto error;
                                 out++;
+                                seg_size = 0;
                                 sgmap = sg_next(sgmap);
                                 pages = 0;
                                 start = i;
@@ -455,6 +461,7 @@ gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, int dir)
                         }
                 }
 
+                seg_size += s->length;
                 need = nextneed;
                 pages += to_pages(s->offset, s->length);
                 ps = s;