linux-kernel - Re: [PATCH v2 03/11] firmware: qcom: scm: switch to using the SCM allocator

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Date:   Thu, 28 Sep 2023 12:11:21 -0700
From:   Elliot Berman <quic_eberman@...cinc.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>,
        Andy Gross <agross@...nel.org>,
        "Bjorn Andersson" <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <kernel@...cinc.com>,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2 03/11] firmware: qcom: scm: switch to using the SCM
 allocator



On 9/28/2023 2:20 AM, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> We need to allocate, map and pass a buffer to the trustzone if we have
> more than 4 arguments for a given SCM calls. Let's use the new SCM
> allocator for that memory and shrink the code in process.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

Reviewed-by: Elliot Berman <quic_eberman@...cinc.com>

> ---
>  drivers/firmware/qcom/qcom_scm-smc.c | 21 ++++-----------------
>  1 file changed, 4 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/firmware/qcom/qcom_scm-smc.c b/drivers/firmware/qcom/qcom_scm-smc.c
> index 16cf88acfa8e..0d5554df1321 100644
> --- a/drivers/firmware/qcom/qcom_scm-smc.c
> +++ b/drivers/firmware/qcom/qcom_scm-smc.c
> @@ -2,6 +2,7 @@
>  /* Copyright (c) 2015,2019 The Linux Foundation. All rights reserved.
>   */
>  
> +#include <linux/cleanup.h>
>  #include <linux/io.h>
>  #include <linux/errno.h>
>  #include <linux/delay.h>
> @@ -152,8 +153,7 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
>  {
>  	int arglen = desc->arginfo & 0xf;
>  	int i, ret;
> -	dma_addr_t args_phys = 0;
> -	void *args_virt = NULL;
> +	void *args_virt __free(qcom_scm_mem) = NULL;
>  	size_t alloc_len;
>  	gfp_t flag = atomic ? GFP_ATOMIC : GFP_KERNEL;
>  	u32 smccc_call_type = atomic ? ARM_SMCCC_FAST_CALL : ARM_SMCCC_STD_CALL;
> @@ -173,7 +173,7 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
>  
>  	if (unlikely(arglen > SCM_SMC_N_REG_ARGS)) {
>  		alloc_len = SCM_SMC_N_EXT_ARGS * sizeof(u64);
> -		args_virt = kzalloc(PAGE_ALIGN(alloc_len), flag);
> +		args_virt = qcom_scm_mem_alloc(PAGE_ALIGN(alloc_len), flag);
>  
>  		if (!args_virt)
>  			return -ENOMEM;
> @@ -192,25 +192,12 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
>  						      SCM_SMC_FIRST_EXT_IDX]);
>  		}
>  
> -		args_phys = dma_map_single(dev, args_virt, alloc_len,
> -					   DMA_TO_DEVICE);
> -
> -		if (dma_mapping_error(dev, args_phys)) {
> -			kfree(args_virt);
> -			return -ENOMEM;
> -		}
> -
> -		smc.args[SCM_SMC_LAST_REG_IDX] = args_phys;
> +		smc.args[SCM_SMC_LAST_REG_IDX] = qcom_scm_mem_to_phys(args_virt);
>  	}
>  
>  	/* ret error check follows after args_virt cleanup*/
>  	ret = __scm_smc_do(dev, &smc, &smc_res, atomic);
>  
> -	if (args_virt) {
> -		dma_unmap_single(dev, args_phys, alloc_len, DMA_TO_DEVICE);
> -		kfree(args_virt);
> -	}
> -
>  	if (ret)
>  		return ret;
>