[PATCH v3 0/6] drm/msm: DMABUF_DEBUG fixes

[PATCH v3 0/6] drm/msm: DMABUF_DEBUG fixes

[Rob Clark]

With DMABUF_DEBUG=y, the page information is stripped from the sgt that
we get for an externally allocated buffer that is dma-buf imported (as
opposed to an exported GEM buffer that is re-imported).  This is a bit
unfortunate, since we need that information for mapping the buffer in
both paths:

1. Userspace GPU pgtables (TTBR0), where we use io_pgtable directly.
   Fortunately this we can fix ourselves easily.

2. Iommu managed pgtables (scanout, kernel GPU buffers (TTBR1)).  In
   normal usage that iommu subsystem envisions the dma-mapping and
   iommu-mapping are combined.  We can't really work around this but
   we can stop trying to pretend to be a normal iommu user and just
   go directly to the iommu_domain_ops.

This all depends on being dma_map_direct() for the dma_map_sgtable()
to work.  This should be the case on modern things that use arm-smmu.
It's less clear when it comes to older pre-arm-smmu hw.  It's possible
that this series causes those things to catch fire.  If so, look to
commit 0e764a01015d ("iommu/arm-smmu: Allow client devices to select
direct mapping") for inspiration.

v3:
- Fixing missing tlb flushes in error paths harder
- Do a single dma_map/unmap_sgtable()
- More paranoid error checking on map path
- Link to v2: https://lore.kernel.org/all/20261027152821.51144-1-robin.clark@oss.qualcomm.com/

v2:
- Fix missing tlb flushes in error paths
- Link to v1: https://lore.kernel.org/all/20261006131000.81501-1-robin.clark@oss.qualcomm.com/

Rob Clark (6):
  drm/msm: Cleanup if pages_to_sg() fails
  drm/msm/gem: dma_map/unmap_sgtable()
  drm/msm: Extract out map/unmap helpers
  drm/msm: Convert iommu map/unmap to helpers
  drm/msm: Convert map helper to use dma-address
  drm/msm: Treat !mapped as an error

 drivers/gpu/drm/msm/msm_gem.c   |  93 +++++++-------
 drivers/gpu/drm/msm/msm_iommu.c | 210 +++++++++++++++++++++-----------
 2 files changed, 184 insertions(+), 119 deletions(-)

-- 
2.56.0

[PATCH v3 1/6] drm/msm: Cleanup if pages_to_sg() fails

[Rob Clark]

We never really handled this.  But in practice mapping to smmu would
have failed without an sgt, which would have been pretty obvious.

Tested-by: Jianfeng Liu <liujianfeng1994@gmail.com> # x1e78100 (Acer SFA14-11), v7.3-rc5 + this series, CONFIG_DMABUF_DEBUG=y
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/msm_gem.c | 41 ++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 130ae27ee00b..181b9ad32672 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -190,6 +190,7 @@ static void update_lru(struct drm_gem_object *obj)
 static struct page **get_pages(struct drm_gem_object *obj)
 {
 	struct msm_gem_object *msm_obj = to_msm_bo(obj);
+	int ret = 0;
 
 	msm_gem_assert_locked(obj);
 
@@ -209,19 +210,17 @@ static struct page **get_pages(struct drm_gem_object *obj)
 			return p;
 		}
 
-		update_device_mem(dev->dev_private, obj->size);
-
 		msm_obj->pages = p;
 
 		msm_obj->sgt = drm_prime_pages_to_sg(obj->dev, p, npages);
 		if (IS_ERR(msm_obj->sgt)) {
-			void *ptr = ERR_CAST(msm_obj->sgt);
-
 			DRM_DEV_ERROR(dev->dev, "failed to allocate sgt\n");
-			msm_obj->sgt = NULL;
-			return ptr;
+			ret = PTR_ERR(msm_obj->sgt);
+			goto error;
 		}
 
+		update_device_mem(dev->dev_private, obj->size);
+
 		/* For non-cached buffers, ensure the new pages are clean
 		 * because display controller, GPU, etc. are not coherent:
 		 */
@@ -232,6 +231,14 @@ static struct page **get_pages(struct drm_gem_object *obj)
 	}
 
 	return msm_obj->pages;
+
+error:
+	msm_obj->sgt = NULL;
+
+	drm_gem_put_pages(obj, msm_obj->pages, false, false);
+	msm_obj->pages = NULL;
+
+	return ERR_PTR(ret);
 }
 
 static void put_pages(struct drm_gem_object *obj)
@@ -246,18 +253,16 @@ static void put_pages(struct drm_gem_object *obj)
 		drm_gpuvm_bo_gem_evict(obj, true);
 
 	if (msm_obj->pages) {
-		if (msm_obj->sgt) {
-			/* For non-cached buffers, ensure the new
-			 * pages are clean because display controller,
-			 * GPU, etc. are not coherent:
-			 */
-			if (msm_obj->flags & MSM_BO_WC)
-				sync_for_cpu(msm_obj);
-
-			sg_free_table(msm_obj->sgt);
-			kfree(msm_obj->sgt);
-			msm_obj->sgt = NULL;
-		}
+		/* For non-cached buffers, ensure the new
+		 * pages are clean because display controller,
+		 * GPU, etc. are not coherent:
+		 */
+		if (msm_obj->flags & MSM_BO_WC)
+			sync_for_cpu(msm_obj);
+
+		sg_free_table(msm_obj->sgt);
+		kfree(msm_obj->sgt);
+		msm_obj->sgt = NULL;
 
 		update_device_mem(obj->dev->dev_private, -obj->size);
 
-- 
2.56.0

[PATCH v3 2/6] drm/msm/gem: dma_map/unmap_sgtable()

[Rob Clark]

This should functionally be a no-op for us, since we are managing our
SMMU directly (dma_map_ops is NULL), but it populates the dma_len/
dma_address's so that we can use them for setting up pgtable mappings.

This inlines sync_for_device() and sync_for_cpu() into their only
callers to avoid doubling up on the dma-mapping calls.

Tested-by: Jianfeng Liu <liujianfeng1994@gmail.com> # x1e78100 (Acer SFA14-11), v7.3-rc5 + this series, CONFIG_DMABUF_DEBUG=y
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/msm_gem.c | 62 ++++++++++++++---------------------
 1 file changed, 25 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 181b9ad32672..c97395e4ea2b 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -116,34 +116,6 @@ void msm_gem_vma_put(struct drm_gem_object *obj)
 #endif
 }
 
-/*
- * Cache sync.. this is a bit over-complicated, to fit dma-mapping
- * API.  Really GPU cache is out of scope here (handled on cmdstream)
- * and all we need to do is invalidate newly allocated pages before
- * mapping to CPU as uncached/writecombine.
- *
- * On top of this, we have the added headache, that depending on
- * display generation, the display's iommu may be wired up to either
- * the toplevel drm device (mdss), or to the mdp sub-node, meaning
- * that here we either have dma-direct or iommu ops.
- *
- * Let this be a cautionary tail of abstraction gone wrong.
- */
-
-static void sync_for_device(struct msm_gem_object *msm_obj)
-{
-	struct device *dev = msm_obj->base.dev->dev;
-
-	dma_map_sgtable(dev, msm_obj->sgt, DMA_BIDIRECTIONAL, 0);
-}
-
-static void sync_for_cpu(struct msm_gem_object *msm_obj)
-{
-	struct device *dev = msm_obj->base.dev->dev;
-
-	dma_unmap_sgtable(dev, msm_obj->sgt, DMA_BIDIRECTIONAL, 0);
-}
-
 static void update_lru_active(struct drm_gem_object *obj)
 {
 	struct msm_drm_private *priv = obj->dev->dev_private;
@@ -201,6 +173,7 @@ static struct page **get_pages(struct drm_gem_object *obj)
 		struct drm_device *dev = obj->dev;
 		struct page **p;
 		size_t npages = obj->size >> PAGE_SHIFT;
+		unsigned map_attrs = DMA_ATTR_SKIP_CPU_SYNC;
 
 		p = drm_gem_get_pages(obj);
 
@@ -219,13 +192,20 @@ static struct page **get_pages(struct drm_gem_object *obj)
 			goto error;
 		}
 
-		update_device_mem(dev->dev_private, obj->size);
-
-		/* For non-cached buffers, ensure the new pages are clean
-		 * because display controller, GPU, etc. are not coherent:
-		 */
+		/* For non-cached buffers, ensure the new pages are clean. */
 		if (msm_obj->flags & MSM_BO_WC)
-			sync_for_device(msm_obj);
+			map_attrs = 0;
+
+		ret = dma_map_sgtable(drm_dev_dma_dev(obj->dev),
+				      msm_obj->sgt,
+				      DMA_BIDIRECTIONAL,
+				      map_attrs);
+		if (ret) {
+			DRM_DEV_ERROR(dev->dev, "could not map sgtable: %d\n", ret);
+			goto error;
+		}
+
+		update_device_mem(dev->dev_private, obj->size);
 
 		update_lru(obj);
 	}
@@ -233,6 +213,8 @@ static struct page **get_pages(struct drm_gem_object *obj)
 	return msm_obj->pages;
 
 error:
+	if (!IS_ERR(msm_obj->sgt))
+		drm_prime_gem_destroy(obj, msm_obj->sgt);
 	msm_obj->sgt = NULL;
 
 	drm_gem_put_pages(obj, msm_obj->pages, false, false);
@@ -253,12 +235,18 @@ static void put_pages(struct drm_gem_object *obj)
 		drm_gpuvm_bo_gem_evict(obj, true);
 
 	if (msm_obj->pages) {
+		unsigned unmap_attrs = DMA_ATTR_SKIP_CPU_SYNC;
+
 		/* For non-cached buffers, ensure the new
-		 * pages are clean because display controller,
-		 * GPU, etc. are not coherent:
+		 * pages are clean:
 		 */
 		if (msm_obj->flags & MSM_BO_WC)
-			sync_for_cpu(msm_obj);
+			unmap_attrs = 0;
+
+		dma_unmap_sgtable(drm_dev_dma_dev(obj->dev),
+				  msm_obj->sgt,
+				  DMA_BIDIRECTIONAL,
+				  unmap_attrs);
 
 		sg_free_table(msm_obj->sgt);
 		kfree(msm_obj->sgt);
-- 
2.56.0

[PATCH v3 3/6] drm/msm: Extract out map/unmap helpers

[Rob Clark]

We're going to re-use these in the next commit.  No functional changes,
just some ugly callbacks.

Tested-by: Jianfeng Liu <liujianfeng1994@gmail.com> # x1e78100 (Acer SFA14-11), v7.3-rc5 + this series, CONFIG_DMABUF_DEBUG=y
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/msm_iommu.c | 159 +++++++++++++++++++++-----------
 1 file changed, 103 insertions(+), 56 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
index da6782fca6bd..5c13ad6d5a36 100644
--- a/drivers/gpu/drm/msm/msm_iommu.c
+++ b/drivers/gpu/drm/msm/msm_iommu.c
@@ -52,9 +52,8 @@ static struct msm_iommu_pagetable *to_pagetable(struct msm_mmu *mmu)
 }
 
 /* based on iommu_pgsize() in iommu.c: */
-static size_t calc_pgsize(struct msm_iommu_pagetable *pagetable,
-			   unsigned long iova, phys_addr_t paddr,
-			   size_t size, size_t *count)
+static size_t calc_pgsize(unsigned long pgsize_bitmap, unsigned long iova,
+			  phys_addr_t paddr, size_t size, size_t *count)
 {
 	unsigned int pgsize_idx, pgsize_idx_next;
 	unsigned long pgsizes;
@@ -62,7 +61,7 @@ static size_t calc_pgsize(struct msm_iommu_pagetable *pagetable,
 	unsigned long addr_merge = paddr | iova;
 
 	/* Page sizes supported by the hardware and small enough for @size */
-	pgsizes = pagetable->pgsize_bitmap & GENMASK(__fls(size), 0);
+	pgsizes = pgsize_bitmap & GENMASK(__fls(size), 0);
 
 	/* Constrain the page sizes further based on the maximum alignment */
 	if (likely(addr_merge))
@@ -78,7 +77,7 @@ static size_t calc_pgsize(struct msm_iommu_pagetable *pagetable,
 		return pgsize;
 
 	/* Find the next biggest support page size, if it exists */
-	pgsizes = pagetable->pgsize_bitmap & ~GENMASK(pgsize_idx, 0);
+	pgsizes = pgsize_bitmap & ~GENMASK(pgsize_idx, 0);
 	if (!pgsizes)
 		goto out_set_count;
 
@@ -107,24 +106,30 @@ static size_t calc_pgsize(struct msm_iommu_pagetable *pagetable,
 	return pgsize;
 }
 
-static int msm_iommu_pagetable_unmap(struct msm_mmu *mmu, u64 iova,
-		size_t size)
+struct map_ops {
+	size_t (*unmap)(void *arg, u64 iova, size_t pgsize, size_t count);
+	int (*map)(void *arg, phys_addr_t padder, u64 iova, size_t pgsize,
+		   size_t pkcount, int prot, size_t *mapped);
+	void (*flush)(void *arg);
+};
+
+static inline int
+__do_unmap(unsigned long pgsize_bitmap, u64 iova, size_t size, void *arg,
+	   const struct map_ops *ops)
 {
-	struct msm_iommu_pagetable *pagetable = to_pagetable(mmu);
-	struct io_pgtable_ops *ops = pagetable->pgtbl_ops;
 	int ret = 0;
 
 	while (size) {
 		size_t pgsize, count;
 		ssize_t unmapped;
 
-		pgsize = calc_pgsize(pagetable, iova, iova, size, &count);
+		pgsize = calc_pgsize(pgsize_bitmap, iova, iova, size, &count);
 
-		unmapped = ops->unmap_pages(ops, iova, pgsize, count, NULL);
+		unmapped = ops->unmap(arg, iova, pgsize, count);
 		if (unmapped <= 0) {
 			ret = -EINVAL;
 			/*
-			 * Continue attempting to unamp the remained of the
+			 * Continue attempting to unmap the remained of the
 			 * range, so we don't end up with some dangling
 			 * mapped pages
 			 */
@@ -135,55 +140,20 @@ static int msm_iommu_pagetable_unmap(struct msm_mmu *mmu, u64 iova,
 		size -= unmapped;
 	}
 
-	iommu_flush_iotlb_all(to_msm_iommu(pagetable->parent)->domain);
+	ops->flush(arg);
 
 	return ret;
 }
 
-static int msm_iommu_pagetable_map_prr(struct msm_mmu *mmu, u64 iova, size_t len, int prot)
+static inline int
+__do_map(unsigned long pgsize_bitmap, u64 iova, struct sg_table *sgt, size_t off,
+	 size_t len, int prot, void *arg, const struct map_ops *ops)
 {
-	struct msm_iommu_pagetable *pagetable = to_pagetable(mmu);
-	struct io_pgtable_ops *ops = pagetable->pgtbl_ops;
-	struct msm_iommu *iommu = to_msm_iommu(pagetable->parent);
-	phys_addr_t phys = page_to_phys(iommu->prr_page);
-	u64 addr = iova;
-
-	while (len) {
-		size_t mapped = 0;
-		size_t size = PAGE_SIZE;
-		int ret;
-
-		ret = ops->map_pages(ops, addr, phys, size, 1, prot, GFP_KERNEL, &mapped);
-
-		/* map_pages could fail after mapping some of the pages,
-		 * so update the counters before error handling.
-		 */
-		addr += mapped;
-		len  -= mapped;
-
-		if (ret) {
-			msm_iommu_pagetable_unmap(mmu, iova, addr - iova);
-			return -EINVAL;
-		}
-	}
-
-	return 0;
-}
-
-static int msm_iommu_pagetable_map(struct msm_mmu *mmu, u64 iova,
-				   struct sg_table *sgt, size_t off, size_t len,
-				   int prot)
-{
-	struct msm_iommu_pagetable *pagetable = to_pagetable(mmu);
-	struct io_pgtable_ops *ops = pagetable->pgtbl_ops;
 	struct scatterlist *sg;
 	u64 addr = iova;
 	unsigned int i;
 
-	if (!sgt)
-		return msm_iommu_pagetable_map_prr(mmu, iova, len, prot);
-
-	for_each_sgtable_sg(sgt, sg, i) {
+	for_each_sgtable_sg (sgt, sg, i) {
 		size_t size = sg->length;
 		phys_addr_t phys = sg_phys(sg);
 
@@ -204,10 +174,9 @@ static int msm_iommu_pagetable_map(struct msm_mmu *mmu, u64 iova,
 			size_t pgsize, count, mapped = 0;
 			int ret;
 
-			pgsize = calc_pgsize(pagetable, addr, phys, size, &count);
+			pgsize = calc_pgsize(pgsize_bitmap, addr, phys, size, &count);
 
-			ret = ops->map_pages(ops, addr, phys, pgsize, count,
-					     prot, GFP_KERNEL, &mapped);
+			ret = ops->map(arg, phys, addr, pgsize, count, prot, &mapped);
 
 			/* map_pages could fail after mapping some of the pages,
 			 * so update the counters before error handling.
@@ -218,7 +187,7 @@ static int msm_iommu_pagetable_map(struct msm_mmu *mmu, u64 iova,
 			len  -= mapped;
 
 			if (ret) {
-				msm_iommu_pagetable_unmap(mmu, iova, addr - iova);
+				__do_unmap(pgsize_bitmap, iova, addr - iova, arg, ops);
 				return -EINVAL;
 			}
 		}
@@ -227,6 +196,84 @@ static int msm_iommu_pagetable_map(struct msm_mmu *mmu, u64 iova,
 	return 0;
 }
 
+static size_t
+__unmap_pgtable(void *arg, u64 iova, size_t pgsize, size_t pgcount)
+{
+	struct msm_iommu_pagetable *pagetable = arg;
+	struct io_pgtable_ops *ops = pagetable->pgtbl_ops;
+	return ops->unmap_pages(ops, iova, pgsize, pgcount, NULL);
+}
+
+static int
+__map_pgtable(void *arg, phys_addr_t paddr, u64 iova, size_t pgsize,
+	      size_t pgcount, int prot, size_t *mapped)
+{
+	struct msm_iommu_pagetable *pagetable = arg;
+	struct io_pgtable_ops *ops = pagetable->pgtbl_ops;
+	return ops->map_pages(ops, iova, paddr, pgsize, pgcount, prot, GFP_KERNEL, mapped);
+}
+
+static void
+__flush_pgtable(void *arg)
+{
+	struct msm_iommu_pagetable *pagetable = arg;
+	iommu_flush_iotlb_all(to_msm_iommu(pagetable->parent)->domain);
+}
+
+static const struct map_ops pgtable_ops = {
+	__unmap_pgtable, __map_pgtable, __flush_pgtable
+};
+
+static int msm_iommu_pagetable_unmap(struct msm_mmu *mmu, u64 iova, size_t size)
+{
+	struct msm_iommu_pagetable *pagetable = to_pagetable(mmu);
+
+	return __do_unmap(pagetable->pgsize_bitmap, iova, size, pagetable, &pgtable_ops);
+}
+
+static int msm_iommu_pagetable_map_prr(struct msm_mmu *mmu, u64 iova, size_t len, int prot)
+{
+	struct msm_iommu_pagetable *pagetable = to_pagetable(mmu);
+	struct io_pgtable_ops *ops = pagetable->pgtbl_ops;
+	struct msm_iommu *iommu = to_msm_iommu(pagetable->parent);
+	phys_addr_t phys = page_to_phys(iommu->prr_page);
+	u64 addr = iova;
+
+	while (len) {
+		size_t mapped = 0;
+		size_t size = PAGE_SIZE;
+		int ret;
+
+		ret = ops->map_pages(ops, addr, phys, size, 1, prot, GFP_KERNEL, &mapped);
+
+		/* map_pages could fail after mapping some of the pages,
+		 * so update the counters before error handling.
+		 */
+		addr += mapped;
+		len  -= mapped;
+
+		if (ret) {
+			msm_iommu_pagetable_unmap(mmu, iova, addr - iova);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int msm_iommu_pagetable_map(struct msm_mmu *mmu, u64 iova,
+				   struct sg_table *sgt, size_t off, size_t len,
+				   int prot)
+{
+	struct msm_iommu_pagetable *pagetable = to_pagetable(mmu);
+
+	if (!sgt)
+		return msm_iommu_pagetable_map_prr(mmu, iova, len, prot);
+
+	return __do_map(pagetable->pgsize_bitmap, iova, sgt, off, len, prot,
+			pagetable, &pgtable_ops);
+}
+
 static void msm_iommu_pagetable_destroy(struct msm_mmu *mmu)
 {
 	struct msm_iommu_pagetable *pagetable = to_pagetable(mmu);
-- 
2.56.0

[PATCH v3 4/6] drm/msm: Convert iommu map/unmap to helpers

[Rob Clark]

Re-use the previously introduced map/unmap helpers in the iommu path
(TTBR1 for GPU, ie. kernel managed buffers, and display/etc).

The callbacks work in terms of iommu_domain/ops instead of io_pgtable.
It would be kinda nice to just deal with io_pgtable, but the tlb ops
that arm-smmu uses for it's own io_pgtable require doing runpm, which
we wouldn't otherwise be able to do.

Tested-by: Jianfeng Liu <liujianfeng1994@gmail.com> # x1e78100 (Acer SFA14-11), v7.3-rc5 + this series, CONFIG_DMABUF_DEBUG=y
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/msm_iommu.c | 43 ++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
index 5c13ad6d5a36..479e5450a4dc 100644
--- a/drivers/gpu/drm/msm/msm_iommu.c
+++ b/drivers/gpu/drm/msm/msm_iommu.c
@@ -731,12 +731,38 @@ static void msm_iommu_detach(struct msm_mmu *mmu)
 	iommu_detach_device(iommu->domain, mmu->dev);
 }
 
+static size_t
+__unmap_iommu(void *arg, u64 iova, size_t pgsize, size_t pgcount)
+{
+	struct iommu_domain *domain = arg;
+	return domain->ops->unmap_pages(domain, iova, pgsize, pgcount, NULL);
+}
+
+static int
+__map_iommu(void *arg, phys_addr_t paddr, u64 iova, size_t pgsize,
+	    size_t pgcount, int prot, size_t *mapped)
+{
+	struct iommu_domain *domain = arg;
+	return domain->ops->map_pages(domain, iova, paddr, pgsize, pgcount,
+				      prot, GFP_KERNEL, mapped);
+}
+
+static void
+__flush_iommu(void *arg)
+{
+	struct iommu_domain *domain = arg;
+	iommu_flush_iotlb_all(domain);
+}
+
+static const struct map_ops iommu_ops = {
+	__unmap_iommu, __map_iommu, __flush_iommu
+};
+
 static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova,
 			 struct sg_table *sgt, size_t off, size_t len,
 			 int prot)
 {
-	struct msm_iommu *iommu = to_msm_iommu(mmu);
-	ssize_t ret;
+	struct iommu_domain *domain = to_msm_iommu(mmu)->domain;
 
 	WARN_ON(off != 0);
 
@@ -744,23 +770,18 @@ static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova,
 	if (iova & BIT_ULL(48))
 		iova |= GENMASK_ULL(63, 49);
 
-	ret = iommu_map_sgtable(iommu->domain, iova, sgt, prot);
-	if (ret < 0)
-		return ret;
-
-	return (ret == len) ? 0 : -EINVAL;
+	return __do_map(domain->pgsize_bitmap, iova, sgt, off, len, prot,
+			domain, &iommu_ops);
 }
 
 static int msm_iommu_unmap(struct msm_mmu *mmu, uint64_t iova, size_t len)
 {
-	struct msm_iommu *iommu = to_msm_iommu(mmu);
+	struct iommu_domain *domain = to_msm_iommu(mmu)->domain;
 
 	if (iova & BIT_ULL(48))
 		iova |= GENMASK_ULL(63, 49);
 
-	iommu_unmap(iommu->domain, iova, len);
-
-	return 0;
+	return __do_unmap(domain->pgsize_bitmap, iova, len, domain, &iommu_ops);
 }
 
 static void msm_iommu_destroy(struct msm_mmu *mmu)
-- 
2.56.0

[PATCH v3 5/6] drm/msm: Convert map helper to use dma-address

[Rob Clark]

Now that we have everything unified in one path, switch over to using
dma addresses for setting up the mapping.  This avoids issues with
CONFIG_DMABUF_DEBUG stripping the pages from the sgt.

Tested-by: Jianfeng Liu <liujianfeng1994@gmail.com> # x1e78100 (Acer SFA14-11), v7.3-rc5 + this series, CONFIG_DMABUF_DEBUG=y
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/msm_iommu.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
index 479e5450a4dc..c2950d32c507 100644
--- a/drivers/gpu/drm/msm/msm_iommu.c
+++ b/drivers/gpu/drm/msm/msm_iommu.c
@@ -153,9 +153,9 @@ __do_map(unsigned long pgsize_bitmap, u64 iova, struct sg_table *sgt, size_t off
 	u64 addr = iova;
 	unsigned int i;
 
-	for_each_sgtable_sg (sgt, sg, i) {
-		size_t size = sg->length;
-		phys_addr_t phys = sg_phys(sg);
+	for_each_sgtable_dma_sg (sgt, sg, i) {
+		size_t size = sg_dma_len(sg);
+		phys_addr_t phys = sg_dma_address(sg);
 
 		if (!len)
 			break;
-- 
2.56.0

[PATCH v3 6/6] drm/msm: Treat !mapped as an error

[Rob Clark]

Rather than silenty mapping nothing, treat this as an error.  It should
never happen, but if it does we want to flag the VM as unusable.

Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/msm_iommu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
index c2950d32c507..255972323f9a 100644
--- a/drivers/gpu/drm/msm/msm_iommu.c
+++ b/drivers/gpu/drm/msm/msm_iommu.c
@@ -186,6 +186,10 @@ __do_map(unsigned long pgsize_bitmap, u64 iova, struct sg_table *sgt, size_t off
 			size -= mapped;
 			len  -= mapped;
 
+			/* If nothing was mapped, consider it an ENOMEM. */
+			if (!ret && !mapped)
+				ret = -ENOMEM;
+
 			if (ret) {
 				__do_unmap(pgsize_bitmap, iova, addr - iova, arg, ops);
 				return -EINVAL;
-- 
2.56.0

Re: [PATCH v3 5/6] drm/msm: Convert map helper to use dma-address

[Dmitry Baryshkov]

On Tue, Oct 27, 2026 at 04:04:48PM -0700, Rob Clark wrote:
> Now that we have everything unified in one path, switch over to using
> dma addresses for setting up the mapping.  This avoids issues with
> CONFIG_DMABUF_DEBUG stripping the pages from the sgt.
> 
> Tested-by: Jianfeng Liu <liujianfeng1994@gmail.com> # x1e78100 (Acer SFA14-11), v7.3-rc5 + this series, CONFIG_DMABUF_DEBUG=y
> Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
> ---
>  drivers/gpu/drm/msm/msm_iommu.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

This commit seems to break GPU on db410c (which uses qcom_iommu).

[  104.954564] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for GPU
to idle!
[  104.954932] msm_mdp 1a01000.display-controller: [drm:adreno_load_gpu]
*ERROR* gpu hw init failed: -22
[  105.958559] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for GPU
to idle!
[  109.082571] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for GPU
to idle!
[  109.082670] msm_mdp 1a01000.display-controller: [drm:adreno_load_gpu]
*ERROR* gpu hw init failed: -22
[  110.086572] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for GPU
to idle!
[  111.098576] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for GPU
to idle!
[  111.098674] msm_mdp 1a01000.display-controller: [drm:adreno_load_gpu]
*ERROR* gpu hw init failed: -22
c[  112.102576] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for
GPU to idle!
> 
> diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
> index 479e5450a4dc..c2950d32c507 100644
> --- a/drivers/gpu/drm/msm/msm_iommu.c
> +++ b/drivers/gpu/drm/msm/msm_iommu.c
> @@ -153,9 +153,9 @@ __do_map(unsigned long pgsize_bitmap, u64 iova, struct sg_table *sgt, size_t off
>  	u64 addr = iova;
>  	unsigned int i;
>  
> -	for_each_sgtable_sg (sgt, sg, i) {
> -		size_t size = sg->length;
> -		phys_addr_t phys = sg_phys(sg);
> +	for_each_sgtable_dma_sg (sgt, sg, i) {
> +		size_t size = sg_dma_len(sg);
> +		phys_addr_t phys = sg_dma_address(sg);
>  
>  		if (!len)
>  			break;
> -- 
> 2.56.0
> 

-- 
With best wishes
Dmitry

Re: [PATCH v3 5/6] drm/msm: Convert map helper to use dma-address

[Rob Clark]

On Tue, Oct 27, 2026 at 6:14 PM Dmitry Baryshkov
<dmitry.baryshkov@oss.qualcomm.com> wrote:
>
> On Tue, Oct 27, 2026 at 04:04:48PM -0700, Rob Clark wrote:
> > Now that we have everything unified in one path, switch over to using
> > dma addresses for setting up the mapping.  This avoids issues with
> > CONFIG_DMABUF_DEBUG stripping the pages from the sgt.
> >
> > Tested-by: Jianfeng Liu <liujianfeng1994@gmail.com> # x1e78100 (Acer SFA14-11), v7.3-rc5 + this series, CONFIG_DMABUF_DEBUG=y
> > Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
> > ---
> >  drivers/gpu/drm/msm/msm_iommu.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
>
> This commit seems to break GPU on db410c (which uses qcom_iommu).
>
> [  104.954564] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for GPU
> to idle!
> [  104.954932] msm_mdp 1a01000.display-controller: [drm:adreno_load_gpu]
> *ERROR* gpu hw init failed: -22
> [  105.958559] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for GPU
> to idle!
> [  109.082571] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for GPU
> to idle!
> [  109.082670] msm_mdp 1a01000.display-controller: [drm:adreno_load_gpu]
> *ERROR* gpu hw init failed: -22
> [  110.086572] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for GPU
> to idle!
> [  111.098576] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for GPU
> to idle!
> [  111.098674] msm_mdp 1a01000.display-controller: [drm:adreno_load_gpu]
> *ERROR* gpu hw init failed: -22
> c[  112.102576] [drm:a3xx_idle] *ERROR* 03000600: timeout waiting for
> GPU to idle!

If that came down to this patch (and not the earlier msm_iommu.c
bits), then I'd look to the hint in the cover letter:

This all depends on being dma_map_direct() for the dma_map_sgtable()
to work.  This should be the case on modern things that use arm-smmu.
It's less clear when it comes to older pre-arm-smmu hw.  It's possible
that this series causes those things to catch fire.  If so, look to
commit 0e764a01015d ("iommu/arm-smmu: Allow client devices to select
direct mapping") for inspiration.


BR,
-R

> >
> > diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
> > index 479e5450a4dc..c2950d32c507 100644
> > --- a/drivers/gpu/drm/msm/msm_iommu.c
> > +++ b/drivers/gpu/drm/msm/msm_iommu.c
> > @@ -153,9 +153,9 @@ __do_map(unsigned long pgsize_bitmap, u64 iova, struct sg_table *sgt, size_t off
> >       u64 addr = iova;
> >       unsigned int i;
> >
> > -     for_each_sgtable_sg (sgt, sg, i) {
> > -             size_t size = sg->length;
> > -             phys_addr_t phys = sg_phys(sg);
> > +     for_each_sgtable_dma_sg (sgt, sg, i) {
> > +             size_t size = sg_dma_len(sg);
> > +             phys_addr_t phys = sg_dma_address(sg);
> >
> >               if (!len)
> >                       break;
> > --
> > 2.56.0
> >
>
> --
> With best wishes
> Dmitry