Re: [PATCH 2/2] firmware: qcom: scm: fall back to kcalloc() for no SCM device bound

[Rudraksha Gupta <guptarud@gmail.com>]

On 9/9/24 11:38, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> Older platforms don't have an actual SCM device tied into the driver
> model and so there's no struct device which to use with the TZ Mem API.
> We need to fall-back to kcalloc() when allocating the buffer for
> additional SMC arguments on such platforms which don't even probe the SCM
> driver and never create the TZMem pool.
>
> Fixes: 449d0d84bcd8 ("firmware: qcom: scm: smc: switch to using the SCM allocator")
> Reported-by: Rudraksha Gupta <guptarud@gmail.com>
> Closes: https://lore.kernel.org/lkml/692cfe9a-8c05-4ce4-813e-82b3f310019a@gmail.com/<S-Del>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> ---
>   drivers/firmware/qcom/qcom_scm-smc.c | 28 ++++++++++++++++++++++++----
>   1 file changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/firmware/qcom/qcom_scm-smc.c b/drivers/firmware/qcom/qcom_scm-smc.c
> index 2b4c2826f572..13f72541033c 100644
> --- a/drivers/firmware/qcom/qcom_scm-smc.c
> +++ b/drivers/firmware/qcom/qcom_scm-smc.c
> @@ -147,6 +147,15 @@ static int __scm_smc_do(struct device *dev, struct arm_smccc_args *smc,
>   	return 0;
>   }
>   
> +static void smc_args_free(void *ptr)
> +{
> +	if (qcom_scm_get_tzmem_pool())
> +		qcom_tzmem_free(ptr);
> +	else
> +		kfree(ptr);
> +}
> +
> +DEFINE_FREE(smc_args, void *, if (!IS_ERR_OR_NULL(_T)) smc_args_free(_T));
>   
>   int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
>   		   enum qcom_scm_convention qcom_convention,
> @@ -155,7 +164,7 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
>   	struct qcom_tzmem_pool *mempool = qcom_scm_get_tzmem_pool();
>   	int arglen = desc->arginfo & 0xf;
>   	int i, ret;
> -	void *args_virt __free(qcom_tzmem) = NULL;
> +	void *args_virt __free(smc_args) = NULL;
>   	gfp_t flag = atomic ? GFP_ATOMIC : GFP_KERNEL;
>   	u32 smccc_call_type = atomic ? ARM_SMCCC_FAST_CALL : ARM_SMCCC_STD_CALL;
>   	u32 qcom_smccc_convention = (qcom_convention == SMC_CONVENTION_ARM_32) ?
> @@ -173,9 +182,20 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
>   		smc.args[i + SCM_SMC_FIRST_REG_IDX] = desc->args[i];
>   
>   	if (unlikely(arglen > SCM_SMC_N_REG_ARGS)) {
> -		args_virt = qcom_tzmem_alloc(mempool,
> -					     SCM_SMC_N_EXT_ARGS * sizeof(u64),
> -					     flag);
> +		/*
> +		 * Older platforms don't have an entry for SCM in device-tree
> +		 * and so no device is bound to the SCM driver. This means there
> +		 * is no struct device for the TZ Mem API. Fall back to
> +		 * kcalloc() on such platforms.
> +		 */
> +		if (mempool)
> +			args_virt = qcom_tzmem_alloc(
> +					mempool,
> +					SCM_SMC_N_EXT_ARGS * sizeof(u64),
> +					flag);
> +		else
> +			args_virt = kcalloc(SCM_SMC_N_EXT_ARGS, sizeof(u64),
> +					    flag);
>   		if (!args_virt)
>   			return -ENOMEM;
>   
>

Tested-by: Rudraksha Gupta <guptarud@gmail.com>