Re: [PATCH v6 05/10] tee: implement restricted DMA-heap

Jens Wiklander
2025-04-01T08:33:17Z

On Tue, Apr 1, 2025 at 9:58 AM Sumit Garg <sumit.garg@kernel.org> wrote:
>
> On Tue, Mar 25, 2025 at 11:55:46AM +0100, Jens Wiklander wrote:
> > Hi Sumit,
> >
>
> <snip>
>
> >
> > >
> > > > +
> > > > +#include "tee_private.h"
> > > > +
> > > > +struct tee_dma_heap {
> > > > + struct dma_heap *heap;
> > > > + enum tee_dma_heap_id id;
> > > > + struct tee_rstmem_pool *pool;
> > > > + struct tee_device *teedev;
> > > > + /* Protects pool and teedev above */
> > > > + struct mutex mu;
> > > > +};
> > > > +
> > > > +struct tee_heap_buffer {
> > > > + struct tee_rstmem_pool *pool;
> > > > + struct tee_device *teedev;
> > > > + size_t size;
> > > > + size_t offs;
> > > > + struct sg_table table;
> > > > +};
> > > > +
> > > > +struct tee_heap_attachment {
> > > > + struct sg_table table;
> > > > + struct device *dev;
> > > > +};
> > > > +
> > > > +struct tee_rstmem_static_pool {
> > > > + struct tee_rstmem_pool pool;
> > > > + struct gen_pool *gen_pool;
> > > > + phys_addr_t pa_base;
> > > > +};
> > > > +
> > > > +#if !IS_MODULE(CONFIG_TEE) && IS_ENABLED(CONFIG_DMABUF_HEAPS)
> > >
> > > Can this dependency rather be better managed via Kconfig?
> >
> > This was the easiest yet somewhat flexible solution I could find. If
> > you have something better, let's use that instead.
> >
>
> --- a/drivers/tee/optee/Kconfig
> +++ b/drivers/tee/optee/Kconfig
> @@ -5,6 +5,7 @@ config OPTEE
> depends on HAVE_ARM_SMCCC
> depends on MMU
> depends on RPMB || !RPMB
> + select DMABUF_HEAPS
> help
> This implements the OP-TEE Trusted Execution Environment (TEE)
> driver.

I wanted to avoid that since there are plenty of use cases where
DMABUF_HEAPS aren't needed. This seems to do the job:
+config TEE_DMABUF_HEAP
+ bool
+ depends on TEE = y && DMABUF_HEAPS

We can only use DMABUF_HEAPS if the TEE subsystem is compiled into the kernel.

Cheers,
Jens