[v5] udmabuf: add vmap and vunmap methods to udmabuf_ops

  The reason behind that patch is associated with videobuf2 subsystem
(or more genrally with v4l2 framework) and user created
dma buffers (udmabuf). In some circumstances
when dealing with V4L2_MEMORY_DMABUF buffers videobuf2 subsystem
wants to use dma_buf_vmap() method on the attached dma buffer.
As udmabuf does not have .vmap operation implemented,
such dma_buf_vmap() natually fails.

videobuf2_common: __vb2_queue_alloc: allocated 3 buffers, 1 plane(s) each
videobuf2_common: __prepare_dmabuf: buffer for plane 0 changed
videobuf2_common: __prepare_dmabuf: failed to map dmabuf for plane 0
videobuf2_common: __buf_prepare: buffer preparation failed: -14

The patch itself seems to be strighforward.
It adds implementation of .vmap and .vunmap methods
to 'struct dma_buf_ops udmabuf_ops'.
.vmap method itself uses vm_map_ram() to map pages linearly
into the kernel virtual address space.
.vunmap removes mapping created earlier by .vmap.
All locking and 'vmapping counting' is done in dma_buf.c
so it seems to be redundant/unnecessary in .vmap/.vunmap.

Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Lukasz Wiecaszek <lukasz.wiecaszek@gmail.com>
---
v1: https://lore.kernel.org/linux-media/202211120352.G7WPASoP-lkp@intel.com/T/#t
v2: https://lore.kernel.org/linux-media/20221114052944.GA7264@thinkpad-p72/T/#t
v3: https://lore.kernel.org/linux-media/4f92e95f-a0dc-4eac-4c08-0df85de78ae7@collabora.com/T/#t
v4: https://lore.kernel.org/linux-media/970e798d-ea26-5e1e-ace8-7915a866f7c7@collabora.com/T/#t

v4 -> v5: Added Acked-by and Reviewed-by to the commit message
v3 -> v4: Removed line/info 'reported by kernel test robot'
v2 -> v3: Added .vunmap to 'struct dma_buf_ops udmabuf_ops'
v1 -> v2: Patch prepared and tested against 6.1.0-rc2+

 drivers/dma-buf/udmabuf.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
  

Pushed this one here to drm-misc-next.

Thanks,
Christian.

Am 17.11.22 um 18:18 schrieb Lukasz Wiecaszek:
> The reason behind that patch is associated with videobuf2 subsystem
> (or more genrally with v4l2 framework) and user created
> dma buffers (udmabuf). In some circumstances
> when dealing with V4L2_MEMORY_DMABUF buffers videobuf2 subsystem
> wants to use dma_buf_vmap() method on the attached dma buffer.
> As udmabuf does not have .vmap operation implemented,
> such dma_buf_vmap() natually fails.
>
> videobuf2_common: __vb2_queue_alloc: allocated 3 buffers, 1 plane(s) each
> videobuf2_common: __prepare_dmabuf: buffer for plane 0 changed
> videobuf2_common: __prepare_dmabuf: failed to map dmabuf for plane 0
> videobuf2_common: __buf_prepare: buffer preparation failed: -14
>
> The patch itself seems to be strighforward.
> It adds implementation of .vmap and .vunmap methods
> to 'struct dma_buf_ops udmabuf_ops'.
> .vmap method itself uses vm_map_ram() to map pages linearly
> into the kernel virtual address space.
> .vunmap removes mapping created earlier by .vmap.
> All locking and 'vmapping counting' is done in dma_buf.c
> so it seems to be redundant/unnecessary in .vmap/.vunmap.
>
> Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
> Acked-by: Christian König <christian.koenig@amd.com>
> Signed-off-by: Lukasz Wiecaszek <lukasz.wiecaszek@gmail.com>
> ---
> v1: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flinux-media%2F202211120352.G7WPASoP-lkp%40intel.com%2FT%2F%23t&amp;data=05%7C01%7Cchristian.koenig%40amd.com%7C9ef170d657a94849986f08dac8bfeb0f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638043023852257558%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=yml6LFzivvU1Vv4cHRf47BEeqRN%2BkH1Sy%2FN4h%2BMpRxU%3D&amp;reserved=0
> v2: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flinux-media%2F20221114052944.GA7264%40thinkpad-p72%2FT%2F%23t&amp;data=05%7C01%7Cchristian.koenig%40amd.com%7C9ef170d657a94849986f08dac8bfeb0f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638043023852257558%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=mBEfWp7w8wTIhO2qF7ad9GrfMyX29EM3neHNHm0i2Zc%3D&amp;reserved=0
> v3: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flinux-media%2F4f92e95f-a0dc-4eac-4c08-0df85de78ae7%40collabora.com%2FT%2F%23t&amp;data=05%7C01%7Cchristian.koenig%40amd.com%7C9ef170d657a94849986f08dac8bfeb0f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638043023852257558%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=2LTn8lzg48%2B%2BTK4w3vctyQ6PjUva%2BZKS8eZeLG%2FWR7I%3D&amp;reserved=0
> v4: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flinux-media%2F970e798d-ea26-5e1e-ace8-7915a866f7c7%40collabora.com%2FT%2F%23t&amp;data=05%7C01%7Cchristian.koenig%40amd.com%7C9ef170d657a94849986f08dac8bfeb0f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638043023852257558%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=tO4Tgd5jPeu6%2BNuWSl%2BSqF%2FEh4dI7vaah4%2FICimHvgo%3D&amp;reserved=0
>
> v4 -> v5: Added Acked-by and Reviewed-by to the commit message
> v3 -> v4: Removed line/info 'reported by kernel test robot'
> v2 -> v3: Added .vunmap to 'struct dma_buf_ops udmabuf_ops'
> v1 -> v2: Patch prepared and tested against 6.1.0-rc2+
>
>   drivers/dma-buf/udmabuf.c | 28 ++++++++++++++++++++++++++++
>   1 file changed, 28 insertions(+)
>
> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
> index 283816fbd72f..740d6e426ee9 100644
> --- a/drivers/dma-buf/udmabuf.c
> +++ b/drivers/dma-buf/udmabuf.c
> @@ -13,6 +13,8 @@
>   #include <linux/slab.h>
>   #include <linux/udmabuf.h>
>   #include <linux/hugetlb.h>
> +#include <linux/vmalloc.h>
> +#include <linux/iosys-map.h>
>   
>   static int list_limit = 1024;
>   module_param(list_limit, int, 0644);
> @@ -60,6 +62,30 @@ static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
>   	return 0;
>   }
>   
> +static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
> +{
> +	struct udmabuf *ubuf = buf->priv;
> +	void *vaddr;
> +
> +	dma_resv_assert_held(buf->resv);
> +
> +	vaddr = vm_map_ram(ubuf->pages, ubuf->pagecount, -1);
> +	if (!vaddr)
> +		return -EINVAL;
> +
> +	iosys_map_set_vaddr(map, vaddr);
> +	return 0;
> +}
> +
> +static void vunmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
> +{
> +	struct udmabuf *ubuf = buf->priv;
> +
> +	dma_resv_assert_held(buf->resv);
> +
> +	vm_unmap_ram(map->vaddr, ubuf->pagecount);
> +}
> +
>   static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
>   				     enum dma_data_direction direction)
>   {
> @@ -162,6 +188,8 @@ static const struct dma_buf_ops udmabuf_ops = {
>   	.unmap_dma_buf	   = unmap_udmabuf,
>   	.release	   = release_udmabuf,
>   	.mmap		   = mmap_udmabuf,
> +	.vmap		   = vmap_udmabuf,
> +	.vunmap		   = vunmap_udmabuf,
>   	.begin_cpu_access  = begin_cpu_udmabuf,
>   	.end_cpu_access    = end_cpu_udmabuf,
>   };