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

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Message-ID: <CAMRc=MfBoekf_5gjF13Acj+zS9H81pA=7=MVYys3E70qvEzUQw@mail.gmail.com>
Date:   Fri, 29 Sep 2023 10:15:00 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     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 Thu, Sep 28, 2023 at 11:21 AM Bartosz Golaszewski <brgl@...ev.pl> 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>
> ---
>  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);

Ah, I realized the PAGE_ALIGN() here can be dropped when switching to
the new allocator.

There'll be a v3 anyway so I'll drop it then.

Bart

>
>                 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;
>
> --
> 2.39.2
>