Regards,
Oak
On 2021-04-21, 9:31 PM, "amd-gfx on behalf of Felix Kuehling" <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx on behalf of Felix.Kuehling@xxxxxxx> wrote:
Use DMABufs with dynamic attachment to DMA-map GTT BOs on other GPUs.
Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 2 +
.../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 76 ++++++++++++++++++-
2 files changed, 77 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
index 63668433f5a6..b706e5a54782 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
@@ -41,6 +41,7 @@ struct amdgpu_device;
enum kfd_mem_attachment_type {
KFD_MEM_ATT_SHARED, /* Share kgd_mem->bo or another attachment's */
KFD_MEM_ATT_USERPTR, /* SG bo to DMA map pages from a userptr bo */
+ KFD_MEM_ATT_DMABUF, /* DMAbuf to DMA map TTM BOs */
};
struct kfd_mem_attachment {
@@ -56,6 +57,7 @@ struct kfd_mem_attachment {
struct kgd_mem {
struct mutex lock;
struct amdgpu_bo *bo;
+ struct dma_buf *dmabuf;
struct list_head attachments;
/* protected by amdkfd_process_info.lock */
struct ttm_validate_buffer validate_list;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 9eeedd0c7920..18a1f9222a59 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -524,6 +524,16 @@ kfd_mem_dmamap_userptr(struct kgd_mem *mem,
return ret;
}
+static int
+kfd_mem_dmamap_dmabuf(struct kfd_mem_attachment *attachment)
+{
+ struct ttm_operation_ctx ctx = {.interruptible = true};
+ struct amdgpu_bo *bo = attachment->bo_va->base.bo;
+
+ amdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);
+ return ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
How does this work? The function name says this is dma mapping a buffer but from the implementation, it is just a placement and validation
+}
+
static int
kfd_mem_dmamap_attachment(struct kgd_mem *mem,
struct kfd_mem_attachment *attachment)
@@ -533,6 +543,8 @@ kfd_mem_dmamap_attachment(struct kgd_mem *mem,
return 0;
case KFD_MEM_ATT_USERPTR:
return kfd_mem_dmamap_userptr(mem, attachment);
+ case KFD_MEM_ATT_DMABUF:
+ return kfd_mem_dmamap_dmabuf(attachment);
default:
WARN_ON_ONCE(1);
}
@@ -562,6 +574,19 @@ kfd_mem_dmaunmap_userptr(struct kgd_mem *mem,
ttm->sg = NULL;
}
+static void
+kfd_mem_dmaunmap_dmabuf(struct kfd_mem_attachment *attachment)
+{
+ struct ttm_operation_ctx ctx = {.interruptible = true};
+ struct amdgpu_bo *bo = attachment->bo_va->base.bo;
+
+ amdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_CPU);
+ ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
+ /* FIXME: This does not guarantee that amdgpu_ttm_tt_unpopulate is
+ * called
+ */
+}
+
static void
kfd_mem_dmaunmap_attachment(struct kgd_mem *mem,
struct kfd_mem_attachment *attachment)
@@ -572,6 +597,9 @@ kfd_mem_dmaunmap_attachment(struct kgd_mem *mem,
case KFD_MEM_ATT_USERPTR:
kfd_mem_dmaunmap_userptr(mem, attachment);
break;
+ case KFD_MEM_ATT_DMABUF:
+ kfd_mem_dmaunmap_dmabuf(attachment);
+ break;
default:
WARN_ON_ONCE(1);
}
@@ -605,6 +633,38 @@ kfd_mem_attach_userptr(struct amdgpu_device *adev, struct kgd_mem *mem,
return 0;
}
+static int
+kfd_mem_attach_dmabuf(struct amdgpu_device *adev, struct kgd_mem *mem,
+ struct amdgpu_bo **bo)
+{
+ struct drm_gem_object *gobj;
+
+ if (!mem->dmabuf) {
+ mem->dmabuf = amdgpu_gem_prime_export(&mem->bo->tbo.base,
+ mem->alloc_flags & KFD_IOC_ALLOC_MEM_FLAGS_WRITABLE ?
+ DRM_RDWR : 0);
+ if (IS_ERR(mem->dmabuf)) {
+ mem->dmabuf = NULL;
+ return PTR_ERR(mem->dmabuf);
+ }
+ }
+
+ gobj = amdgpu_gem_prime_import(&adev->ddev, mem->dmabuf);
+ if (IS_ERR(gobj))
+ return PTR_ERR(gobj);
+
+ /* Import takes an extra reference on the dmabuf. Drop it now to
+ * avoid leaking it. We only need the one reference in
+ * kgd_mem->dmabuf.
+ */
+ dma_buf_put(mem->dmabuf);
+
+ *bo = gem_to_amdgpu_bo(gobj);
+ (*bo)->parent = amdgpu_bo_ref(mem->bo);
+
+ return 0;
+}
+
/* kfd_mem_attach - Add a BO to a VM
*
* Everything that needs to bo done only once when a BO is first added
@@ -662,8 +722,20 @@ static int kfd_mem_attach(struct amdgpu_device *adev, struct kgd_mem *mem,
ret = kfd_mem_attach_userptr(adev, mem, &bo[i]);
if (ret)
goto unwind;
+ } else if (mem->domain == AMDGPU_GEM_DOMAIN_GTT &&
+ mem->bo->tbo.type != ttm_bo_type_sg) {
+ /* GTT BOs use DMA-mapping ability of dynamic-attach
+ * DMA bufs. TODO: The same should work for VRAM on
+ * large-BAR GPUs.
+ */
+ attachment[i]->type = KFD_MEM_ATT_DMABUF;
+ ret = kfd_mem_attach_dmabuf(adev, mem, &bo[i]);
+ if (ret)
+ goto unwind;
} else {
- /* FIXME: Need to DMA-map other BO types */
+ /* FIXME: Need to DMA-map other BO types:
+ * large-BAR VRAM, doorbells, MMIO remap
+ */
attachment[i]->type = KFD_MEM_ATT_SHARED;
bo[i] = mem->bo;
drm_gem_object_get(&bo[i]->tbo.base);
@@ -1522,6 +1594,8 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
/* Free the BO*/
drm_vma_node_revoke(&mem->bo->tbo.base.vma_node, drm_priv);
+ if (mem->dmabuf)
+ dma_buf_put(mem->dmabuf);
drm_gem_object_put(&mem->bo->tbo.base);
mutex_destroy(&mem->lock);
kfree(mem);
--
2.31.1
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