Re: [PATCH] drm/nouveau: Fixup gk20a instobj hierarchy

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On 08/12/2023 10:46, Thierry Reding wrote:
From: Thierry Reding <treding@xxxxxxxxxx>

Commit 12c9b05da918 ("drm/nouveau/imem: support allocations not
preserved across suspend") uses container_of() to cast from struct
nvkm_memory to struct nvkm_instobj, assuming that all instance objects
are derived from struct nvkm_instobj. For the gk20a family that's not
the case and they are derived from struct nvkm_memory instead. This
causes some subtle data corruption (nvkm_instobj.preserve ends up
mapping to gk20a_instobj.vaddr) that causes a NULL pointer dereference
in gk20a_instobj_acquire_iommu() (and possibly elsewhere) and also
prevents suspend/resume from working.

Fix this by making struct gk20a_instobj derive from struct nvkm_instobj
instead.

Fixes: 12c9b05da918 ("drm/nouveau/imem: support allocations not preserved across suspend")
Reported-by: Jonathan Hunter <jonathanh@xxxxxxxxxx>
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
Note that this was probably subtly wrong before the above-mentioned
commit already, but I don't think we've seen any reports that would
indicate any actual failures related to this before. So I think it's
good enough to apply this fix for v6.7. The next closest thing would
be commit d8e83994aaf6 ("drm/nouveau/imem: improve management of
instance memory"), but that's 8 years old (Linux v4.3)...
---
  .../drm/nouveau/nvkm/subdev/instmem/gk20a.c    | 18 +++++++++---------
  1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c b/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
index 1b811d6972a1..201022ae9214 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
@@ -49,14 +49,14 @@
  #include <subdev/mmu.h>
struct gk20a_instobj {
-	struct nvkm_memory memory;
+	struct nvkm_instobj base;
  	struct nvkm_mm_node *mn;
  	struct gk20a_instmem *imem;
/* CPU mapping */
  	u32 *vaddr;
  };
-#define gk20a_instobj(p) container_of((p), struct gk20a_instobj, memory)
+#define gk20a_instobj(p) container_of((p), struct gk20a_instobj, base.memory)
/*
   * Used for objects allocated using the DMA API
@@ -148,7 +148,7 @@ gk20a_instobj_iommu_recycle_vaddr(struct gk20a_instobj_iommu *obj)
  	list_del(&obj->vaddr_node);
  	vunmap(obj->base.vaddr);
  	obj->base.vaddr = NULL;
-	imem->vaddr_use -= nvkm_memory_size(&obj->base.memory);
+	imem->vaddr_use -= nvkm_memory_size(&obj->base.base.memory);
  	nvkm_debug(&imem->base.subdev, "vaddr used: %x/%x\n", imem->vaddr_use,
  		   imem->vaddr_max);
  }
@@ -283,7 +283,7 @@ gk20a_instobj_map(struct nvkm_memory *memory, u64 offset, struct nvkm_vmm *vmm,
  {
  	struct gk20a_instobj *node = gk20a_instobj(memory);
  	struct nvkm_vmm_map map = {
-		.memory = &node->memory,
+		.memory = &node->base.memory,
  		.offset = offset,
  		.mem = node->mn,
  	};
@@ -391,8 +391,8 @@ gk20a_instobj_ctor_dma(struct gk20a_instmem *imem, u32 npages, u32 align,
  		return -ENOMEM;
  	*_node = &node->base;
- nvkm_memory_ctor(&gk20a_instobj_func_dma, &node->base.memory);
-	node->base.memory.ptrs = &gk20a_instobj_ptrs;
+	nvkm_memory_ctor(&gk20a_instobj_func_dma, &node->base.base.memory);
+	node->base.base.memory.ptrs = &gk20a_instobj_ptrs;
node->base.vaddr = dma_alloc_attrs(dev, npages << PAGE_SHIFT,
  					   &node->handle, GFP_KERNEL,
@@ -438,8 +438,8 @@ gk20a_instobj_ctor_iommu(struct gk20a_instmem *imem, u32 npages, u32 align,
  	*_node = &node->base;
  	node->dma_addrs = (void *)(node->pages + npages);
- nvkm_memory_ctor(&gk20a_instobj_func_iommu, &node->base.memory);
-	node->base.memory.ptrs = &gk20a_instobj_ptrs;
+	nvkm_memory_ctor(&gk20a_instobj_func_iommu, &node->base.base.memory);
+	node->base.base.memory.ptrs = &gk20a_instobj_ptrs;
/* Allocate backing memory */
  	for (i = 0; i < npages; i++) {
@@ -533,7 +533,7 @@ gk20a_instobj_new(struct nvkm_instmem *base, u32 size, u32 align, bool zero,
  	else
  		ret = gk20a_instobj_ctor_dma(imem, size >> PAGE_SHIFT,
  					     align, &node);
-	*pmemory = node ? &node->memory : NULL;
+	*pmemory = node ? &node->base.memory : NULL;
  	if (ret)
  		return ret;


Tested-by: Jon Hunter <jonathanh@xxxxxxxxxx>

Thanks!
Jon

--
nvpublic




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