Re: [PATCH 00/10] Add mediate-drm secure flow for SVP

[CK Hu (胡俊光)]

Hi, Jason:

On Tue, 2023-09-19 at 11:03 +0800, Jason-JH.Lin wrote:
> The patch series provides drm driver support for enabling secure
> video
> path (SVP) playback on MediaiTek hardware in the Linux kernel.
> 
> Memory Definitions:
> secure memory - Memory allocated in the TEE (Trusted Execution
> Environment) which is inaccessible in the REE (Rich Execution
> Environment, i.e. linux kernel/userspace).
> secure handle - Integer value which acts as reference to 'secure
> memory'. Used in communication between TEE and REE to reference
> 'secure memory'.
> secure buffer - 'secure memory' that is used to store decrypted,
> compressed video or for other general purposes in the TEE.
> secure surface - 'secure memory' that is used to store graphic
> buffers.
> 
> Memory Usage in SVP:
> The overall flow of SVP starts with encrypted video coming in from an
> outside source into the REE. The REE will then allocate a 'secure
> buffer' and send the corresponding 'secure handle' along with the
> encrypted, compressed video data to the TEE. The TEE will then
> decrypt
> the video and store the result in the 'secure buffer'. The REE will
> then allocate a 'secure surface'. The REE will pass the 'secure
> handles' for both the 'secure buffer' and 'secure surface' into the
> TEE for video decoding. The video decoder HW will then decode the
> contents of the 'secure buffer' and place the result in the 'secure
> surface'. The REE will then attach the 'secure surface' to the
> overlay
> plane for rendering of the video.
> 
> Everything relating to ensuring security of the actual contents of
> the
> 'secure buffer' and 'secure surface' is out of scope for the REE and
> is the responsibility of the TEE.
> 
> DRM driver handles allocation of gem objects that are backed by a
> 'secure
> surface' and for displaying a 'secure surface' on the overlay plane.
> This introduces a new flag for object creation called
> DRM_MTK_GEM_CREATE_ENCRYPTED which indicates it should be a 'secure
> surface'. All changes here are in MediaTek specific code.

How do you define SVP? Is there standard requirement we could refer to?
If the secure video buffer is read by display hardware and output to
HDMI without any protection and user could capture HDMI signal, is this
secure?

Regards,
CK

> 
> ---
> Based on 2 series:
> [1] Add CMDQ secure driver for SVP
> - 
> https://urldefense.com/v3/__https://patchwork.kernel.org/project/linux-mediatek/list/?series=785332__;!!CTRNKA9wMg0ARbw!mPocbQwZ4-25DmidvAgd9K5eXjNEhSyIKpvvYHPpdrq2PgS-hkYyHohzDvoJydD45UZp5JvY9DuDVFj1ltVnhGY$
>  
> 
> [2] dma-buf: heaps: Add MediaTek secure heap
> - 
> https://urldefense.com/v3/__https://patchwork.kernel.org/project/linux-mediatek/list/?series=782776__;!!CTRNKA9wMg0ARbw!mPocbQwZ4-25DmidvAgd9K5eXjNEhSyIKpvvYHPpdrq2PgS-hkYyHohzDvoJydD45UZp5JvY9DuDVFj10sD4kHE$
>  
> ---
> 
> CK Hu (1):
>   drm/mediatek: Add interface to allocate MediaTek GEM buffer.
> 
> Jason-JH.Lin (9):
>   drm/mediatek/uapi: Add DRM_MTK_GEM_CREATED_ENCRYPTTED flag
>   drm/mediatek: Add secure buffer control flow to mtk_drm_gem
>   drm/mediatek: Add secure identify flag and funcution to
> mtk_drm_plane
>   drm/mediatek: Add mtk_ddp_sec_write to config secure buffer info
>   drm/mediatek: Add get_sec_port interface to mtk_ddp_comp
>   drm/mediatek: Add secure layer config support for ovl
>   drm/mediatek: Add secure layer config support for ovl_adaptor
>   drm/mediatek: Add secure flow support to mediatek-drm
>   arm64: dts: mt8195-cherry: Add secure mbox settings for vdosys
> 
>  .../boot/dts/mediatek/mt8195-cherry.dtsi      |  10 +
>  drivers/gpu/drm/mediatek/mtk_disp_drv.h       |   3 +
>  drivers/gpu/drm/mediatek/mtk_disp_ovl.c       |  31 +-
>  .../gpu/drm/mediatek/mtk_disp_ovl_adaptor.c   |  15 +
>  drivers/gpu/drm/mediatek/mtk_drm_crtc.c       | 271
> +++++++++++++++++-
>  drivers/gpu/drm/mediatek/mtk_drm_crtc.h       |   1 +
>  drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c   |  14 +
>  drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h   |  13 +
>  drivers/gpu/drm/mediatek/mtk_drm_drv.c        |  16 +-
>  drivers/gpu/drm/mediatek/mtk_drm_gem.c        | 121 ++++++++
>  drivers/gpu/drm/mediatek/mtk_drm_gem.h        |  16 ++
>  drivers/gpu/drm/mediatek/mtk_drm_plane.c      |   7 +
>  drivers/gpu/drm/mediatek/mtk_drm_plane.h      |   2 +
>  drivers/gpu/drm/mediatek/mtk_mdp_rdma.c       |  11 +-
>  drivers/gpu/drm/mediatek/mtk_mdp_rdma.h       |   2 +
>  include/uapi/drm/mediatek_drm.h               |  59 ++++
>  16 files changed, 575 insertions(+), 17 deletions(-)
>  create mode 100644 include/uapi/drm/mediatek_drm.h
>