Re: [PATCH v3 7/7] remoteproc: stm32: Add support of an OP-TEE TA to load the firmware

[Mathieu Poirier]

Hi,

On Wed, Feb 14, 2024 at 06:21:27PM +0100, Arnaud Pouliquen wrote:
> The new TEE remoteproc device 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.
> 
> A new "to_attach" field is introduced to differentiate the use cases
> "firmware loaded by the boot stage" and "firmware loaded by the TEE".
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>
> ---
> V2 to V3 update:
> - remove stm32_rproc_tee_elf_sanity_check(), stm32_rproc_tee_elf_load()
>   stm32_rproc_tee_elf_find_loaded_rsc_table() and  stm32_rproc_tee_start() that are bnow unused
> - use new rproc::alt_boot field to sepcify that the alternate fboot method is used
> - use stm32_rproc::to_attach field to differenciate attch mode from remoteproc tee boot mode.
> - remove the used of stm32_rproc::fw_loaded
> ---
>  drivers/remoteproc/stm32_rproc.c | 85 +++++++++++++++++++++++++++++---
>  1 file changed, 79 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/remoteproc/stm32_rproc.c b/drivers/remoteproc/stm32_rproc.c
> index fcc0001e2657..9cfcf66462e0 100644
> --- a/drivers/remoteproc/stm32_rproc.c
> +++ b/drivers/remoteproc/stm32_rproc.c
> @@ -20,6 +20,7 @@
>  #include <linux/remoteproc.h>
>  #include <linux/reset.h>
>  #include <linux/slab.h>
> +#include <linux/tee_remoteproc.h>
>  #include <linux/workqueue.h>
>  
>  #include "remoteproc_internal.h"
> @@ -49,6 +50,9 @@
>  #define M4_STATE_STANDBY	4
>  #define M4_STATE_CRASH		5
>  
> +/* Remote processor unique identifier aligned with the Trusted Execution Environment definitions */
> +#define STM32_MP1_M4_PROC_ID    0
> +
>  struct stm32_syscon {
>  	struct regmap *map;
>  	u32 reg;
> @@ -90,6 +94,8 @@ struct stm32_rproc {
>  	struct stm32_mbox mb[MBOX_NB_MBX];
>  	struct workqueue_struct *workqueue;
>  	bool hold_boot_smc;
> +	bool to_attach;
> +	struct tee_rproc *trproc;
>  	void __iomem *rsc_va;
>  };
>  
> @@ -253,10 +259,30 @@ static int stm32_rproc_release(struct rproc *rproc)
>  			return err;
>  		}
>  	}
> +	ddata->to_attach = false;
>  
>  	return err;
>  }
>  
> +static int stm32_rproc_tee_attach(struct rproc *rproc)
> +{
> +	/* Nothing to do, remote proc already started by the secured context. */
> +	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;
> @@ -637,10 +663,14 @@ stm32_rproc_get_loaded_rsc_table(struct rproc *rproc, size_t *table_sz)
>  {
>  	struct stm32_rproc *ddata = rproc->priv;
>  	struct device *dev = rproc->dev.parent;
> +	struct tee_rproc *trproc = ddata->trproc;
>  	phys_addr_t rsc_pa;
>  	u32 rsc_da;
>  	int err;
>  
> +	if (trproc && !ddata->to_attach)
> +		return tee_rproc_get_loaded_rsc_table(rproc, table_sz);
> +

Why do we need a flag at all?  Why can't st_rproc_tee_ops::get_loaded_rsc_table
be set to tee_rproc_get_loaded_rsc_table()?

>  	/* The resource table has already been mapped, nothing to do */
>  	if (ddata->rsc_va)
>  		goto done;
> @@ -693,8 +723,20 @@ 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,
> +	.attach		= stm32_rproc_tee_attach,
> +	.kick		= stm32_rproc_kick,
> +	.get_loaded_rsc_table = stm32_rproc_get_loaded_rsc_table,
> +	.find_loaded_rsc_table = tee_rproc_find_loaded_rsc_table,
> +	.load		= tee_rproc_load_fw,
> +};
> +
>  static const struct of_device_id stm32_rproc_match[] = {
> -	{ .compatible = "st,stm32mp1-m4" },
> +	{.compatible = "st,stm32mp1-m4",},
> +	{.compatible = "st,stm32mp1-m4-tee",},
>  	{},
>  };
>  MODULE_DEVICE_TABLE(of, stm32_rproc_match);
> @@ -853,6 +895,7 @@ 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;
>  	struct rproc *rproc;
>  	unsigned int state;
>  	int ret;
> @@ -861,12 +904,33 @@ static int stm32_rproc_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	rproc = rproc_alloc(dev, np->name, &st_rproc_ops, NULL, sizeof(*ddata));
> -	if (!rproc)
> -		return -ENOMEM;

This patch doesn't apply to rproc-next - please rebase.


> +	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.
> +		 */
> +		trproc = tee_rproc_register(dev, STM32_MP1_M4_PROC_ID);
> +		if (IS_ERR(trproc)) {
> +			dev_err_probe(dev, PTR_ERR(trproc),
> +				      "signed firmware not supported by TEE\n");
> +			return PTR_ERR(trproc);
> +		}
> +	}
>  
> -	ddata = rproc->priv;
> +	rproc = rproc_alloc(dev, np->name,
> +			    trproc ? &st_rproc_tee_ops : &st_rproc_ops,
> +			    NULL, sizeof(*ddata));
> +	if (!rproc) {
> +		ret = -ENOMEM;
> +		goto free_tee;
> +	}
>  
> +	ddata = rproc->priv;
> +	ddata->trproc = trproc;

My opinion hasn't changed from the previous patchet, i.e tee_rproc should be
folded in struct rproc as rproc::tee_interface.

More comments to come shortly...

> +	if (trproc) {
> +		rproc->alt_boot = true;
> +		trproc->rproc = rproc;
> +	}
>  	rproc_coredump_set_elf_info(rproc, ELFCLASS32, EM_NONE);
>  
>  	ret = stm32_rproc_parse_dt(pdev, ddata, &rproc->auto_boot);
> @@ -881,8 +945,10 @@ static int stm32_rproc_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto free_rproc;
>  
> -	if (state == M4_STATE_CRUN)
> +	if (state == M4_STATE_CRUN) {
>  		rproc->state = RPROC_DETACHED;
> +		ddata->to_attach = true;
> +	}
>  
>  	rproc->has_iommu = false;
>  	ddata->workqueue = create_workqueue(dev_name(dev));
> @@ -916,6 +982,10 @@ static int stm32_rproc_probe(struct platform_device *pdev)
>  		device_init_wakeup(dev, false);
>  	}
>  	rproc_free(rproc);
> +free_tee:
> +	if (trproc)
> +		tee_rproc_unregister(trproc);
> +
>  	return ret;
>  }
>  
> @@ -923,6 +993,7 @@ static void stm32_rproc_remove(struct platform_device *pdev)
>  {
>  	struct rproc *rproc = platform_get_drvdata(pdev);
>  	struct stm32_rproc *ddata = rproc->priv;
> +	struct tee_rproc *trproc = ddata->trproc;
>  	struct device *dev = &pdev->dev;
>  
>  	if (atomic_read(&rproc->power) > 0)
> @@ -937,6 +1008,8 @@ static void stm32_rproc_remove(struct platform_device *pdev)
>  		device_init_wakeup(dev, false);
>  	}
>  	rproc_free(rproc);
> +	if (trproc)
> +		tee_rproc_unregister(trproc);
>  }
>  
>  static int stm32_rproc_suspend(struct device *dev)
> -- 
> 2.25.1
>