linux-kernel - Re: [PATCH v2 06/11] firmware: qcom: scm: make qcom_scm_pas_init

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Date:   Fri, 29 Sep 2023 14:16:51 -0500
From:   Andrew Halaney <ahalaney@...hat.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     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>,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        kernel@...cinc.com,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2 06/11] firmware: qcom: scm: make
 qcom_scm_pas_init_image() use the SCM allocator

On Thu, Sep 28, 2023 at 11:20:35AM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> Let's use the new SCM memory allocator to obtain a buffer for this call
> instead of using dma_alloc_coherent().
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
>  drivers/firmware/qcom/qcom_scm.c | 16 +++++-----------
>  1 file changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> index 02a773ba1383..c0eb81069847 100644
> --- a/drivers/firmware/qcom/qcom_scm.c
> +++ b/drivers/firmware/qcom/qcom_scm.c
> @@ -532,7 +532,7 @@ static void qcom_scm_set_download_mode(bool enable)
>  int qcom_scm_pas_init_image(u32 peripheral, const void *metadata, size_t size,
>  			    struct qcom_scm_pas_metadata *ctx)
>  {
> -	dma_addr_t mdata_phys;
> +	phys_addr_t mdata_phys;

>  	void *mdata_buf;
>  	int ret;
>  	struct qcom_scm_desc desc = {
> @@ -544,13 +544,7 @@ int qcom_scm_pas_init_image(u32 peripheral, const void *metadata, size_t size,
>  	};
>  	struct qcom_scm_res res;
>  
> -	/*
> -	 * During the scm call memory protection will be enabled for the meta
> -	 * data blob, so make sure it's physically contiguous, 4K aligned and
> -	 * non-cachable to avoid XPU violations.
> -	 */
> -	mdata_buf = dma_alloc_coherent(__scm->dev, size, &mdata_phys,
> -				       GFP_KERNEL);
> +	mdata_buf = qcom_scm_mem_alloc(size, GFP_KERNEL);

mdata_phys is never initialized now, and its what's being shoved into
desc.args[1] later, which I believe is what triggered the -EINVAL
with qcom_scm_call() that I reported in my cover letter reply this
morning.

Prior with the DMA API that would have been the device view of the buffer.

>  	if (!mdata_buf) {
>  		dev_err(__scm->dev, "Allocation of metadata buffer failed.\n");
>  		return -ENOMEM;
> @@ -574,10 +568,10 @@ int qcom_scm_pas_init_image(u32 peripheral, const void *metadata, size_t size,
>  
>  out:
>  	if (ret < 0 || !ctx) {
> -		dma_free_coherent(__scm->dev, size, mdata_buf, mdata_phys);
> +		qcom_scm_mem_free(mdata_buf);
>  	} else if (ctx) {
>  		ctx->ptr = mdata_buf;
> -		ctx->phys = mdata_phys;
> +		ctx->phys = qcom_scm_mem_to_phys(mdata_buf);
>  		ctx->size = size;
>  	}
>  
> @@ -594,7 +588,7 @@ void qcom_scm_pas_metadata_release(struct qcom_scm_pas_metadata *ctx)
>  	if (!ctx->ptr)
>  		return;
>  
> -	dma_free_coherent(__scm->dev, ctx->size, ctx->ptr, ctx->phys);
> +	qcom_scm_mem_free(ctx->ptr);
>  
>  	ctx->ptr = NULL;
>  	ctx->phys = 0;
> -- 
> 2.39.2
>