[PATCH v4 0/3] drm/virtio: fix mmap page attributes

[PATCH v4 0/3] drm/virtio: fix mmap page attributes

[Gerd Hoffmann]

v4: back to v2-ish design, but simplified a bit.
v3: switch to drm_gem_object_funcs callback.
v2: make shmem helper caching configurable.

Gerd Hoffmann (3):
  drm/shmem: add support for per object caching flags.
  drm/virtio: fix mmap page attributes
  drm/udl: simplify gem object mapping.

 include/drm/drm_gem_shmem_helper.h      |  5 ++
 drivers/gpu/drm/drm_gem_shmem_helper.c  | 12 +++--
 drivers/gpu/drm/udl/udl_gem.c           | 62 ++-----------------------
 drivers/gpu/drm/virtio/virtgpu_object.c |  1 +
 4 files changed, 18 insertions(+), 62 deletions(-)

-- 
2.18.1

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[PATCH v4 1/3] drm/shmem: add support for per object caching flags.

[Gerd Hoffmann]

Add map_cached bool to drm_gem_shmem_object, to request cached mappings
on a per-object base.  Check the flag before adding writecombine to
pgprot bits.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 include/drm/drm_gem_shmem_helper.h     |  5 +++++
 drivers/gpu/drm/drm_gem_shmem_helper.c | 12 +++++++++---
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 6748379a0b44..e69f58d467c6 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -83,6 +83,11 @@ struct drm_gem_shmem_object {
 	 * The address are un-mapped when the count reaches zero.
 	 */
 	unsigned int vmap_use_count;
+
+	/**
+	 * @map_cached: map object cached (instead of using writecombine).
+	 */
+	bool map_cached;
 };
 
 #define to_drm_gem_shmem_obj(obj) \
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index a421a2eed48a..443265a4fc5a 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -256,9 +256,13 @@ static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
 
 	if (obj->import_attach)
 		shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
-	else
+	else {
+		pgprot_t prot = PAGE_KERNEL;
+		if (!shmem->map_cached)
+			prot = pgprot_writecombine(prot);
 		shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
-				    VM_MAP, pgprot_writecombine(PAGE_KERNEL));
+				    VM_MAP, prot);
+	}
 
 	if (!shmem->vaddr) {
 		DRM_DEBUG_KMS("Failed to vmap pages\n");
@@ -540,7 +544,9 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
 	}
 
 	vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;
-	vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
+	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+	if (!shmem->map_cached)
+		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 	vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
 	vma->vm_ops = &drm_gem_shmem_vm_ops;
 
-- 
2.18.1

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[PATCH v4 2/3] drm/virtio: fix mmap page attributes

[Gerd Hoffmann]

virtio-gpu uses cached mappings, set
drm_gem_shmem_object.map_cached accordingly.

Reported-by: Gurchetan Singh <gurchetansingh@chromium.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

virtio fixup
---
 drivers/gpu/drm/virtio/virtgpu_object.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c
index 017a9e0fc3bb..7f991e03ea2c 100644
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -99,6 +99,7 @@ struct drm_gem_object *virtio_gpu_create_object(struct drm_device *dev,
 		return NULL;
 
 	bo->base.base.funcs = &virtio_gpu_gem_funcs;
+	bo->base.map_cached = true;
 	return &bo->base.base;
 }
 
-- 
2.18.1

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[PATCH v4 3/3] drm/udl: simplify gem object mapping.

[Gerd Hoffmann]

With shmem helpers allowing to update pgprot caching flags via
drm_gem_shmem_object.map_cached we can just use that and ditch
our own implementations of mmap() and vmap().

We also don't need a special case for imported objects, any map
requests are handled by the exporter not udl.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 drivers/gpu/drm/udl/udl_gem.c | 62 ++---------------------------------
 1 file changed, 3 insertions(+), 59 deletions(-)

diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c
index b6e26f98aa0a..7e3a88b25b6b 100644
--- a/drivers/gpu/drm/udl/udl_gem.c
+++ b/drivers/gpu/drm/udl/udl_gem.c
@@ -17,72 +17,15 @@
  * GEM object funcs
  */
 
-static int udl_gem_object_mmap(struct drm_gem_object *obj,
-			       struct vm_area_struct *vma)
-{
-	int ret;
-
-	ret = drm_gem_shmem_mmap(obj, vma);
-	if (ret)
-		return ret;
-
-	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
-	if (obj->import_attach)
-		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
-	vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
-
-	return 0;
-}
-
-static void *udl_gem_object_vmap(struct drm_gem_object *obj)
-{
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
-	int ret;
-
-	ret = mutex_lock_interruptible(&shmem->vmap_lock);
-	if (ret)
-		return ERR_PTR(ret);
-
-	if (shmem->vmap_use_count++ > 0)
-		goto out;
-
-	ret = drm_gem_shmem_get_pages(shmem);
-	if (ret)
-		goto err_zero_use;
-
-	if (obj->import_attach)
-		shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
-	else
-		shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
-				    VM_MAP, PAGE_KERNEL);
-
-	if (!shmem->vaddr) {
-		DRM_DEBUG_KMS("Failed to vmap pages\n");
-		ret = -ENOMEM;
-		goto err_put_pages;
-	}
-
-out:
-	mutex_unlock(&shmem->vmap_lock);
-	return shmem->vaddr;
-
-err_put_pages:
-	drm_gem_shmem_put_pages(shmem);
-err_zero_use:
-	shmem->vmap_use_count = 0;
-	mutex_unlock(&shmem->vmap_lock);
-	return ERR_PTR(ret);
-}
-
 static const struct drm_gem_object_funcs udl_gem_object_funcs = {
 	.free = drm_gem_shmem_free_object,
 	.print_info = drm_gem_shmem_print_info,
 	.pin = drm_gem_shmem_pin,
 	.unpin = drm_gem_shmem_unpin,
 	.get_sg_table = drm_gem_shmem_get_sg_table,
-	.vmap = udl_gem_object_vmap,
+	.vmap = drm_gem_shmem_vmap,
 	.vunmap = drm_gem_shmem_vunmap,
-	.mmap = udl_gem_object_mmap,
+	.mmap = drm_gem_shmem_mmap,
 };
 
 /*
@@ -101,6 +44,7 @@ struct drm_gem_object *udl_driver_gem_create_object(struct drm_device *dev,
 
 	obj = &shmem->base;
 	obj->funcs = &udl_gem_object_funcs;
+	shmem->map_cached = true;
 
 	return obj;
 }
-- 
2.18.1

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Re: [PATCH v4 3/3] drm/udl: simplify gem object mapping.

[Chia-I Wu]

On Wed, Dec 18, 2019 at 4:56 AM Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> With shmem helpers allowing to update pgprot caching flags via
> drm_gem_shmem_object.map_cached we can just use that and ditch
> our own implementations of mmap() and vmap().
>
> We also don't need a special case for imported objects, any map
> requests are handled by the exporter not udl.
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  drivers/gpu/drm/udl/udl_gem.c | 62 ++---------------------------------
>  1 file changed, 3 insertions(+), 59 deletions(-)
>
> diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c
> index b6e26f98aa0a..7e3a88b25b6b 100644
> --- a/drivers/gpu/drm/udl/udl_gem.c
> +++ b/drivers/gpu/drm/udl/udl_gem.c
> @@ -17,72 +17,15 @@
>   * GEM object funcs
>   */
>
> -static int udl_gem_object_mmap(struct drm_gem_object *obj,
> -                              struct vm_area_struct *vma)
> -{
> -       int ret;
> -
> -       ret = drm_gem_shmem_mmap(obj, vma);
> -       if (ret)
> -               return ret;
> -
> -       vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> -       if (obj->import_attach)
> -               vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
> -       vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
> -
> -       return 0;
> -}
> -
> -static void *udl_gem_object_vmap(struct drm_gem_object *obj)
> -{
> -       struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> -       int ret;
> -
> -       ret = mutex_lock_interruptible(&shmem->vmap_lock);
> -       if (ret)
> -               return ERR_PTR(ret);
> -
> -       if (shmem->vmap_use_count++ > 0)
> -               goto out;
> -
> -       ret = drm_gem_shmem_get_pages(shmem);
> -       if (ret)
> -               goto err_zero_use;
> -
> -       if (obj->import_attach)
> -               shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
> -       else
> -               shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
> -                                   VM_MAP, PAGE_KERNEL);
> -
> -       if (!shmem->vaddr) {
> -               DRM_DEBUG_KMS("Failed to vmap pages\n");
> -               ret = -ENOMEM;
> -               goto err_put_pages;
> -       }
> -
> -out:
> -       mutex_unlock(&shmem->vmap_lock);
> -       return shmem->vaddr;
> -
> -err_put_pages:
> -       drm_gem_shmem_put_pages(shmem);
> -err_zero_use:
> -       shmem->vmap_use_count = 0;
> -       mutex_unlock(&shmem->vmap_lock);
> -       return ERR_PTR(ret);
> -}
> -
>  static const struct drm_gem_object_funcs udl_gem_object_funcs = {
>         .free = drm_gem_shmem_free_object,
>         .print_info = drm_gem_shmem_print_info,
>         .pin = drm_gem_shmem_pin,
>         .unpin = drm_gem_shmem_unpin,
>         .get_sg_table = drm_gem_shmem_get_sg_table,
> -       .vmap = udl_gem_object_vmap,
> +       .vmap = drm_gem_shmem_vmap,
>         .vunmap = drm_gem_shmem_vunmap,
> -       .mmap = udl_gem_object_mmap,
> +       .mmap = drm_gem_shmem_mmap,
>  };
It looks like we can just use the default ops (drm_gem_shmem_funcs).

With that, this series is

  Reviewed-by: Chia-I Wu <olvaffe@gmail.com>.

>
>  /*
> @@ -101,6 +44,7 @@ struct drm_gem_object *udl_driver_gem_create_object(struct drm_device *dev,
>
>         obj = &shmem->base;
>         obj->funcs = &udl_gem_object_funcs;
> +       shmem->map_cached = true;
>
>         return obj;
>  }
> --
> 2.18.1
>
> _______________________________________________
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> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
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