Re: [PATCH v2 2/7] drm/amdgpu: Implement mmap as GEM object function

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Am 15.04.21 um 14:11 schrieb Thomas Zimmermann:
Hi

Am 15.04.21 um 13:38 schrieb Christian König:
Am 15.04.21 um 12:17 schrieb Thomas Zimmermann:
Moving the driver-specific mmap code into a GEM object function allows
for using DRM helpers for various mmap callbacks.

This change resolves several inconsistencies between regular mmap and
prime-based mmap. The vm_ops field in vma is now set for all mmap'ed
areas. Previously it way only set for regular mmap calls, prime-based
mmap used TTM's default vm_ops. The function amdgpu_verify_access() is
no longer being called and therefore removed by this patch.

As a side effect, amdgpu_ttm_vm_ops and amdgpu_ttm_fault() are now
implemented in amdgpu's GEM code.

v2:
    * rename amdgpu_ttm_vm_ops and amdgpu_ttm_fault() to
      amdgpu_gem_vm_ops and amdgpu_gem_fault() (Christian)
    * the check for kfd_bo has meanwhile been removed

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>

[SNIP]
+static int amdgpu_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
+{

Mhm, just double checking this function is now a core GEM function and not prime specific?

If yes maybe drop the _prime part.

No problem, but other functions in the GEM callbacks are also named _prime_. Probably needs a clean-up.

Yeah, some still needs to be renamed. But there shouldn't be any left in amdgpu_gem.c



+    struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+    struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
+    unsigned long asize = amdgpu_bo_size(bo);
+
+    if (!vma->vm_file)
+        return -ENODEV;
+
+    if (!adev)
+        return -ENODEV;
+
+    /* Check for valid size. */
+    if (asize < vma->vm_end - vma->vm_start)
+        return -EINVAL;

Shouldn't we have that check in the common code?

It's at [1]. I didn't really bother about tidying up the checks themselves. We can drop all these except for the usermm branch below. Same for the radeon patch.

In this case I would just drop that from both amdgpu and radeon.

Thanks,
Christian.


Best regards
Thomas

[1] https://elixir.bootlin.com/linux/v5.12-rc7/source/drivers/gpu/drm/drm_gem.c#L1059


Apart from that looks good to me.

Christian.

+
+    if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm) ||
+        (bo->flags & AMDGPU_GEM_CREATE_NO_CPU_ACCESS)) {
+        return -EPERM;
+    }
+
+    return drm_gem_ttm_mmap(obj, vma);
+}
+
  static const struct drm_gem_object_funcs amdgpu_gem_object_funcs = {
      .free = amdgpu_gem_object_free,
      .open = amdgpu_gem_object_open,
@@ -212,6 +266,8 @@ static const struct drm_gem_object_funcs amdgpu_gem_object_funcs = {
      .export = amdgpu_gem_prime_export,
      .vmap = drm_gem_ttm_vmap,
      .vunmap = drm_gem_ttm_vunmap,
+    .mmap = amdgpu_gem_prime_mmap,
+    .vm_ops = &amdgpu_gem_vm_ops,
  };
  /*
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 1485f33c3cc7..d4083c19402b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -152,25 +152,6 @@ static void amdgpu_evict_flags(struct ttm_buffer_object *bo,
      *placement = abo->placement;
  }
-/**
- * amdgpu_verify_access - Verify access for a mmap call
- *
- * @bo:    The buffer object to map
- * @filp: The file pointer from the process performing the mmap
- *
- * This is called by ttm_bo_mmap() to verify whether a process
- * has the right to mmap a BO to their process space.
- */
-static int amdgpu_verify_access(struct ttm_buffer_object *bo, struct file *filp)
-{
-    struct amdgpu_bo *abo = ttm_to_amdgpu_bo(bo);
-
-    if (amdgpu_ttm_tt_get_usermm(bo->ttm))
-        return -EPERM;
-    return drm_vma_node_verify_access(&abo->tbo.base.vma_node,
-                      filp->private_data);
-}
-
  /**
   * amdgpu_ttm_map_buffer - Map memory into the GART windows
   * @bo: buffer object to map
@@ -1522,7 +1503,6 @@ static struct ttm_device_funcs amdgpu_bo_driver = {
      .eviction_valuable = amdgpu_ttm_bo_eviction_valuable,
      .evict_flags = &amdgpu_evict_flags,
      .move = &amdgpu_bo_move,
-    .verify_access = &amdgpu_verify_access,
      .delete_mem_notify = &amdgpu_bo_delete_mem_notify,
      .release_notify = &amdgpu_bo_release_notify,
      .io_mem_reserve = &amdgpu_ttm_io_mem_reserve,
@@ -1897,50 +1877,6 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
      adev->mman.buffer_funcs_enabled = enable;
  }
-static vm_fault_t amdgpu_ttm_fault(struct vm_fault *vmf)
-{
-    struct ttm_buffer_object *bo = vmf->vma->vm_private_data;
-    vm_fault_t ret;
-
-    ret = ttm_bo_vm_reserve(bo, vmf);
-    if (ret)
-        return ret;
-
-    ret = amdgpu_bo_fault_reserve_notify(bo);
-    if (ret)
-        goto unlock;
-
-    ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot,
-                       TTM_BO_VM_NUM_PREFAULT, 1);
-    if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
-        return ret;
-
-unlock:
-    dma_resv_unlock(bo->base.resv);
-    return ret;
-}
-
-static const struct vm_operations_struct amdgpu_ttm_vm_ops = {
-    .fault = amdgpu_ttm_fault,
-    .open = ttm_bo_vm_open,
-    .close = ttm_bo_vm_close,
-    .access = ttm_bo_vm_access
-};
-
-int amdgpu_mmap(struct file *filp, struct vm_area_struct *vma)
-{
-    struct drm_file *file_priv = filp->private_data;
-    struct amdgpu_device *adev = drm_to_adev(file_priv->minor->dev);
-    int r;
-
-    r = ttm_bo_mmap(filp, vma, &adev->mman.bdev);
-    if (unlikely(r != 0))
-        return r;
-
-    vma->vm_ops = &amdgpu_ttm_vm_ops;
-    return 0;
-}
-
  int amdgpu_copy_buffer(struct amdgpu_ring *ring, uint64_t src_offset,
                 uint64_t dst_offset, uint32_t byte_count,
                 struct dma_resv *resv,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
index dec0db8b0b13..6e51faad7371 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
@@ -146,7 +146,6 @@ int amdgpu_fill_buffer(struct amdgpu_bo *bo,
              struct dma_resv *resv,
              struct dma_fence **fence);
-int amdgpu_mmap(struct file *filp, struct vm_area_struct *vma);
  int amdgpu_ttm_alloc_gart(struct ttm_buffer_object *bo);
  int amdgpu_ttm_recover_gart(struct ttm_buffer_object *tbo);
  uint64_t amdgpu_ttm_domain_start(struct amdgpu_device *adev, uint32_t type);



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