On Thu, 30 Jan 2025 17:15:24 +0100 Simona Vetter <simona.vetter@xxxxxxxx> wrote: > On Thu, Jan 30, 2025 at 01:08:56PM +0000, Florent Tomasin wrote: > > Hi, > > > > This is a patch series covering the support for protected mode execution in > > Mali Panthor CSF kernel driver. > > > > The Mali CSF GPUs come with the support for protected mode execution at the > > HW level. This feature requires two main changes in the kernel driver: > > > > 1) Configure the GPU with a protected buffer. The system must provide a DMA > > heap from which the driver can allocate a protected buffer. > > It can be a carved-out memory or dynamically allocated protected memory region. > > Some system includes a trusted FW which is in charge of the protected memory. > > Since this problem is integration specific, the Mali Panthor CSF kernel > > driver must import the protected memory from a device specific exporter. > > > > 2) Handle enter and exit of the GPU HW from normal to protected mode of execution. > > FW sends a request for protected mode entry to the kernel driver. > > The acknowledgment of that request is a scheduling decision. Effectively, > > protected mode execution should not overrule normal mode of execution. > > A fair distribution of execution time will guaranty the overall performance > > of the device, including the UI (usually executing in normal mode), > > will not regress when a protected mode job is submitted by an application. > > > > > > Background > > ---------- > > > > Current Mali Panthor CSF driver does not allow a user space application to > > execute protected jobs on the GPU. This use case is quite common on end-user-device. > > A user may want to watch a video or render content that is under a "Digital Right > > Management" protection, or launch an application with user private data. > > > > 1) User-space: > > > > In order for an application to execute protected jobs on a Mali CSF GPU the > > user space application must submit jobs to the GPU within a "protected regions" > > (range of commands to execute in protected mode). > > > > Find here an example of a command buffer that contains protected commands: > > > > ``` > > <--- Normal mode ---><--- Protected mode ---><--- Normal mode ---> > > +-------------------------------------------------------------------------+ > > | ... | CMD_0 | ... | CMD_N | PROT_REGION | CMD_N+1 | ... | CMD_N+M | ... | > > +-------------------------------------------------------------------------+ > > ``` > > > > The PROT_REGION command acts as a barrier to notify the HW of upcoming > > protected jobs. It also defines the number of commands to execute in protected > > mode. > > > > The Mesa definition of the opcode can be found here: > > > > https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/panfrost/lib/genxml/v10.xml?ref_type=heads#L763 > > Is there also something around that implements egl_ext_protected_context > or similar in mesa? I'll be looking at a mesa implementation for EGL_EXT_protected_content in the coming weeks. I'll probably get back to reviewing the panthor implementation when I have something working in mesa. > I think that's the minimal bar all the protected gpu > workload kernel support patches cleared thus far, since usually getting > the actual video code stuff published seems to be impossible.
