Re: [PATCH v11 7/7] remoteproc: stm32: Add support of an OP-TEE TA to load the firmware

Mathieu Poirier
2024-10-22T15:52:13Z

On Wed, Oct 09, 2024 at 10:01:08AM +0200, Arnaud Pouliquen wrote:
> The new TEE remoteproc driver is used to manage remote firmware in a
> secure, trusted context. The 'st,stm32mp1-m4-tee' compatibility is
> introduced to delegate the loading of the firmware to the trusted
> execution context. In such cases, the firmware should be signed and
> adhere to the image format defined by the TEE.
>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> ---
> updates vs v9 revision:
> - rename tee_interface to tee_rproc_itf
> - in stm32_rproc_probe(), test and use rproc->tee_rproc_itf instead of
> trproc in the tee_rproc_unregister() call
> - initialize release_fw ops
> ---
> drivers/remoteproc/stm32_rproc.c | 63 ++++++++++++++++++++++++++++++--
> 1 file changed, 60 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/remoteproc/stm32_rproc.c b/drivers/remoteproc/stm32_rproc.c
> index 288bd70c7861..cb7093de41df 100644
> --- a/drivers/remoteproc/stm32_rproc.c
> +++ b/drivers/remoteproc/stm32_rproc.c
> @@ -18,6 +18,7 @@
> #include <linux/pm_wakeirq.h>
> #include <linux/regmap.h>
> #include <linux/remoteproc.h>
> +#include <linux/remoteproc_tee.h>
> #include <linux/reset.h>
> #include <linux/slab.h>
> #include <linux/workqueue.h>
> @@ -255,6 +256,19 @@ static int stm32_rproc_release(struct rproc *rproc)
> return 0;
> }
>
> +static int stm32_rproc_tee_stop(struct rproc *rproc)
> +{
> + int err;
> +
> + stm32_rproc_request_shutdown(rproc);
> +
> + err = tee_rproc_stop(rproc);
> + if (err)
> + return err;
> +
> + return stm32_rproc_release(rproc);
> +}
> +
> static int stm32_rproc_prepare(struct rproc *rproc)
> {
> struct device *dev = rproc->dev.parent;
> @@ -691,8 +705,20 @@ static const struct rproc_ops st_rproc_ops = {
> .get_boot_addr = rproc_elf_get_boot_addr,
> };
>
> +static const struct rproc_ops st_rproc_tee_ops = {
> + .prepare = stm32_rproc_prepare,
> + .start = tee_rproc_start,
> + .stop = stm32_rproc_tee_stop,
> + .kick = stm32_rproc_kick,
> + .load = tee_rproc_load_fw,
> + .parse_fw = tee_rproc_parse_fw,
> + .find_loaded_rsc_table = tee_rproc_find_loaded_rsc_table,
> + .release_fw = tee_rproc_release_fw,
> +};
> +
> static const struct of_device_id stm32_rproc_match[] = {
> { .compatible = "st,stm32mp1-m4" },
> + { .compatible = "st,stm32mp1-m4-tee" },
> {},
> };
> MODULE_DEVICE_TABLE(of, stm32_rproc_match);
> @@ -851,17 +877,42 @@ static int stm32_rproc_probe(struct platform_device *pdev)
> struct device *dev = &pdev->dev;
> struct stm32_rproc *ddata;
> struct device_node *np = dev->of_node;
> + struct tee_rproc *trproc = NULL;

The cleaner this patchset get, the more obvious it is (at least to me) that
struct tee_rproc needs to be changed to struct rproc_tee. Otherwise I keep
wondering if this is coming from the TEE subsystem or the remoteproc subsystem.

> struct rproc *rproc;
> unsigned int state;
> + u32 proc_id;
> int ret;
>
> ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(32));
> if (ret)
> return ret;
>
> - rproc = devm_rproc_alloc(dev, np->name, &st_rproc_ops, NULL, sizeof(*ddata));
> - if (!rproc)
> - return -ENOMEM;
> + if (of_device_is_compatible(np, "st,stm32mp1-m4-tee")) {
> + /*
> + * Delegate the firmware management to the secure context.
> + * The firmware loaded has to be signed.
> + */
> + ret = of_property_read_u32(np, "st,proc-id", &proc_id);
> + if (ret) {
> + dev_err(dev, "failed to read st,rproc-id property\n");
> + return ret;
> + }
> +
> + rproc = devm_rproc_alloc(dev, np->name, &st_rproc_tee_ops, NULL, sizeof(*ddata));
> + if (!rproc)
> + return -ENOMEM;
> +
> + trproc = tee_rproc_register(dev, rproc, proc_id);

This should return an integer rather than a struct tee_rproc * since the latter
is available through rproc->tee_rproc_itf.

In line with my comment above, this should be changed to rproc_tee_register()
since it belongs to the remoteproc subsystem. Before when I asked for
tee_remoteproc.c to be changed to remoteproc_tee.c, I thought we could get by
without changing the inside but now I think it is clear that we can't - this
needs to be addressed.

> + if (IS_ERR(trproc)) {
> + dev_err_probe(dev, PTR_ERR(trproc),
> + "signed firmware not supported by TEE\n");
> + return PTR_ERR(trproc);

return dev_err_probe(...);
> + }
> + } else {
> + rproc = devm_rproc_alloc(dev, np->name, &st_rproc_ops, NULL, sizeof(*ddata));
> + if (!rproc)
> + return -ENOMEM;
> + }
>
> ddata = rproc->priv;
>
> @@ -913,6 +964,9 @@ static int stm32_rproc_probe(struct platform_device *pdev)
> dev_pm_clear_wake_irq(dev);
> device_init_wakeup(dev, false);
> }
> + if (rproc->tee_rproc_itf)
> + tee_rproc_unregister(rproc->tee_rproc_itf);
> +

If I read Bjorn's comment properly, this should probably be:

rproc_tee_unregister(rproc);

with the if() inside the function.

> return ret;
> }
>
> @@ -933,6 +987,9 @@ static void stm32_rproc_remove(struct platform_device *pdev)
> dev_pm_clear_wake_irq(dev);
> device_init_wakeup(dev, false);
> }
> + if (rproc->tee_rproc_itf)
> + tee_rproc_unregister(rproc->tee_rproc_itf);
> +

Same here.

I am done reviewing this set.

Thanks,
Mathieu

> }
>
> static int stm32_rproc_suspend(struct device *dev)
> --
> 2.25.1
>