[PATCH v3 0/2] drm: fix virtio-gpu + sev

[Daniel Vetter]

On Mon, Sep 07, 2020 at 08:33:41AM +0200, Gerd Hoffmann wrote:
> virtio-gpu must make sure scatter list segments are not too big.
> 
> Gerd Hoffmann (2):
>   drm: allow limiting the scatter list size.
>   drm/virtio: set max_segment

So this all feels a bit irky and mid-layer, and why can't the various
helpers not just use dma_max_mapping_size(drm_device->dev) directly.

And then I read that dma api use in virtio subsystem is a huge mess of
hacks, and that it doesn't set up these quirks through the dma api
abstraction but throught it's own abstraction on top. So we don't really
have any other option I think.

I think would be good to add a TODO item to the virtio_max_dma_size call
like:

	TODO: once virtio uses the dma api correctly, remove the explicit
	max_segment handling na duse dma_max_mapping_size directly
	everywhere.

Or maybe also put that into the @max_segment kerneldoc in the drm_device
struct.

With that: Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch> on the
series.
-Daniel

> 
>  include/drm/drm_device.h                    |  8 ++++++++
>  include/drm/drm_prime.h                     |  3 ++-
>  drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c |  3 ++-
>  drivers/gpu/drm/drm_gem_shmem_helper.c      |  3 ++-
>  drivers/gpu/drm/drm_prime.c                 | 10 +++++++---
>  drivers/gpu/drm/etnaviv/etnaviv_gem.c       |  3 ++-
>  drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c |  3 ++-
>  drivers/gpu/drm/msm/msm_gem.c               |  3 ++-
>  drivers/gpu/drm/msm/msm_gem_prime.c         |  3 ++-
>  drivers/gpu/drm/nouveau/nouveau_prime.c     |  3 ++-
>  drivers/gpu/drm/radeon/radeon_prime.c       |  3 ++-
>  drivers/gpu/drm/rockchip/rockchip_drm_gem.c |  6 ++++--
>  drivers/gpu/drm/tegra/gem.c                 |  3 ++-
>  drivers/gpu/drm/vgem/vgem_drv.c             |  3 ++-
>  drivers/gpu/drm/virtio/virtgpu_kms.c        |  1 +
>  drivers/gpu/drm/xen/xen_drm_front_gem.c     |  3 ++-
>  16 files changed, 44 insertions(+), 17 deletions(-)
> 
> -- 
> 2.27.0
> 
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch