From: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
When walking DMA mapped scatterlists sg_dma_len has to be used since it
can be different (coalesced) from the backing store entry.
This also means we have to end the walk when encountering a zero length
DMA entry and cannot rely on the normal sg list end marker.
Both issues were there in theory for some time but were hidden by the fact
Intel IOMMU driver was never coalescing entries. As there are ongoing
efforts to change this we need to start handling it.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
References: 85d1225ec066 ("drm/i915: Introduce & use new lightweight SGL
iterators")
References: b31144c0daa8 ("drm/i915: Micro-optimise
gen6_ppgtt_insert_entries()")
Reported-by: Tom Murphy <murph...@tcd.ie>
Suggested-by: Tom Murphy <murph...@tcd.ie> # __sgt_iter
Suggested-by: Logan Gunthorpe <log...@deltatee.com> # __sgt_iter
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.a...@intel.com>
Cc: Lu Baolu <baolu...@linux.intel.com>
---
drivers/gpu/drm/i915/gt/gen6_ppgtt.c | 6 +++---
drivers/gpu/drm/i915/gt/gen8_ppgtt.c | 17 ++++++++++-------
drivers/gpu/drm/i915/gt/intel_gtt.h | 2 +-
drivers/gpu/drm/i915/i915_scatterlist.h | 12 ++++++++----
4 files changed, 22 insertions(+), 15 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
index fd0d24d28763..c0d17f87b00f 100644
--- a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
+++ b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
@@ -131,17 +131,17 @@ static void gen6_ppgtt_insert_entries(struct
i915_address_space *vm,
vaddr = kmap_atomic_px(i915_pt_entry(pd, act_pt));
do {
- GEM_BUG_ON(iter.sg->length < I915_GTT_PAGE_SIZE);
+ GEM_BUG_ON(sg_dma_len(iter.sg) < I915_GTT_PAGE_SIZE);
vaddr[act_pte] = pte_encode | GEN6_PTE_ADDR_ENCODE(iter.dma);
iter.dma += I915_GTT_PAGE_SIZE;
if (iter.dma == iter.max) {
iter.sg = __sg_next(iter.sg);
- if (!iter.sg)
+ if (!iter.sg || sg_dma_len(iter.sg) == 0)
break;
iter.dma = sg_dma_address(iter.sg);
- iter.max = iter.dma + iter.sg->length;
+ iter.max = iter.dma + sg_dma_len(iter.sg);
}
if (++act_pte == GEN6_PTES) {
diff --git a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
index eb64f474a78c..0361b3dfdc72 100644
--- a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
+++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
@@ -372,19 +372,19 @@ gen8_ppgtt_insert_pte(struct i915_ppgtt *ppgtt,
pd = i915_pd_entry(pdp, gen8_pd_index(idx, 2));
vaddr = kmap_atomic_px(i915_pt_entry(pd, gen8_pd_index(idx, 1)));
do {
- GEM_BUG_ON(iter->sg->length < I915_GTT_PAGE_SIZE);
+ GEM_BUG_ON(sg_dma_len(iter->sg) < I915_GTT_PAGE_SIZE);
vaddr[gen8_pd_index(idx, 0)] = pte_encode | iter->dma;
iter->dma += I915_GTT_PAGE_SIZE;
if (iter->dma >= iter->max) {
iter->sg = __sg_next(iter->sg);
- if (!iter->sg) {
+ if (!iter->sg || sg_dma_len(iter->sg) == 0) {
idx = 0;
break;
}
iter->dma = sg_dma_address(iter->sg);
- iter->max = iter->dma + iter->sg->length;
+ iter->max = iter->dma + sg_dma_len(iter->sg);
}
if (gen8_pd_index(++idx, 0) == 0) {
@@ -414,7 +414,7 @@ static void gen8_ppgtt_insert_huge(struct i915_vma *vma,
{
const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, flags);
u64 start = vma->node.start;
- dma_addr_t rem = iter->sg->length;
+ dma_addr_t rem = sg_dma_len(iter->sg);
