From: Matthew Auld <matthew.auld@intel.com>
Date: Fri, 28 Oct 2022 15:50:26 +0000 (+0100)
Subject: drm/i915/dmabuf: fix sg_table handling in map_dma_buf
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=f90daa975911961b65070ec72bd7dd8d448f9ef7;p=linux.git

drm/i915/dmabuf: fix sg_table handling in map_dma_buf

We need to iterate over the original entries here for the sg_table,
pulling out the struct page for each one, to be remapped. However
currently this incorrectly iterates over the final dma mapped entries,
which is likely just one gigantic sg entry if the iommu is enabled,
leading to us only mapping the first struct page (and any physically
contiguous pages following it), even if there is potentially lots more
data to follow.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/7306
Fixes: 1286ff739773 ("i915: add dmabuf/prime buffer sharing support.")
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Michael J. Ruhl <michael.j.ruhl@intel.com>
Cc: <stable@vger.kernel.org> # v3.5+
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221028155029.494736-1-matthew.auld@intel.com
(cherry picked from commit 28d52f99bbca7227008cf580c9194c9b3516968e)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
index f5062d0c63336..824971a1ceece 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
@@ -40,13 +40,13 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme
 		goto err;
 	}
 
-	ret = sg_alloc_table(st, obj->mm.pages->nents, GFP_KERNEL);
+	ret = sg_alloc_table(st, obj->mm.pages->orig_nents, GFP_KERNEL);
 	if (ret)
 		goto err_free;
 
 	src = obj->mm.pages->sgl;
 	dst = st->sgl;
-	for (i = 0; i < obj->mm.pages->nents; i++) {
+	for (i = 0; i < obj->mm.pages->orig_nents; i++) {
 		sg_set_page(dst, sg_page(src), src->length, 0);
 		dst = sg_next(dst);
 		src = sg_next(src);