On Tue, Sep 19, 2023 at 10:26 PM CK Hu (胡俊光) <ck.hu@xxxxxxxxxxxx> wrote: > > 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? SVP (Secure Video Path) is essentially the video being completed isolated from the kernel/userspace. The specific requirements for it vary between implementations. Regarding HDMI/HDCP output; it's the responsibility of the TEE to enforce that. Nothing on the kernel/userspace side needs to be concerned about enforcing HDCP. The only thing userspace is involved in there is actually turning on HDCP via the kernel drivers; and then the TEE ensures that it is active if the policy for the encrypted content requires it. > > 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 > >
