[RESEND PATCH v5 03/12] firmware: qcom: scm: smc: switch to using the SCM allocator

[Prasad Sodagudi]

On 11/20/2023 5:21 AM, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski at linaro.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 TrustZone
> allocator for that memory and shrink the code in process.
>
> As this code lives in a different compilation unit than the rest of the
> SCM code, we need to provide a helper in the form of
> qcom_scm_get_tzmem_pool() that allows the SMC low-level routines to
> access the SCM memory pool.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski at linaro.org>
> Reviewed-by: Andrew Halaney <ahalaney at redhat.com>
> Tested-by: Andrew Halaney <ahalaney at redhat.com> # sc8280xp-lenovo-thinkpad-x13s
> ---
>   drivers/firmware/qcom/qcom_scm-smc.c | 30 ++++++++--------------------
>   drivers/firmware/qcom/qcom_scm.c     |  5 +++++
>   drivers/firmware/qcom/qcom_scm.h     |  3 +++
>   3 files changed, 16 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/firmware/qcom/qcom_scm-smc.c b/drivers/firmware/qcom/qcom_scm-smc.c
> index 16cf88acfa8e..dca5f3f1883b 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>
> @@ -9,6 +10,7 @@
>   #include <linux/slab.h>
>   #include <linux/types.h>
>   #include <linux/firmware/qcom/qcom_scm.h>
> +#include <linux/firmware/qcom/qcom_tzmem.h>
>   #include <linux/arm-smccc.h>
>   #include <linux/dma-mapping.h>
>   
> @@ -150,11 +152,10 @@ int __scm_smc_call(struct device *dev, const struct qcom_scm_desc *desc,
>   		   enum qcom_scm_convention qcom_convention,
>   		   struct qcom_scm_res *res, bool atomic)
>   {
> +	struct qcom_tzmem_pool *mempool = qcom_scm_get_tzmem_pool();
>   	int arglen = desc->arginfo & 0xf;
>   	int i, ret;
> -	dma_addr_t args_phys = 0;
> -	void *args_virt = NULL;
> -	size_t alloc_len;
> +	void *args_virt __free(qcom_tzmem) = 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) ?
> @@ -172,9 +173,9 @@ 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)) {
> -		alloc_len = SCM_SMC_N_EXT_ARGS * sizeof(u64);
> -		args_virt = kzalloc(PAGE_ALIGN(alloc_len), flag);
> -
> +		args_virt = qcom_tzmem_alloc(mempool,
> +					     SCM_SMC_N_EXT_ARGS * sizeof(u64),
> +					     flag);

I remember seeing page alignment for this memory allocation in 
downstream code too.

I think, after moving to qcom_tzmem_alloc page alignment is not 
followed. Is this cross checked with firmware requirements?

>   		if (!args_virt)
>   			return -ENOMEM;
>   
> @@ -192,25 +193,10 @@ 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_tzmem_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;
>   
> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> index 0d4c028be0c1..71e98b666391 100644
> --- a/drivers/firmware/qcom/qcom_scm.c
> +++ b/drivers/firmware/qcom/qcom_scm.c
> @@ -201,6 +201,11 @@ static void qcom_scm_bw_disable(void)
>   enum qcom_scm_convention qcom_scm_convention = SMC_CONVENTION_UNKNOWN;
>   static DEFINE_SPINLOCK(scm_query_lock);
>   
> +struct qcom_tzmem_pool *qcom_scm_get_tzmem_pool(void)
> +{
> +	return __scm->mempool;
> +}
> +
>   static enum qcom_scm_convention __get_convention(void)
>   {
>   	unsigned long flags;
> diff --git a/drivers/firmware/qcom/qcom_scm.h b/drivers/firmware/qcom/qcom_scm.h
> index 4532907e8489..aa7d06939f8e 100644
> --- a/drivers/firmware/qcom/qcom_scm.h
> +++ b/drivers/firmware/qcom/qcom_scm.h
> @@ -5,6 +5,7 @@
>   #define __QCOM_SCM_INT_H
>   
>   struct device;
> +struct qcom_tzmem_pool;
>   
>   enum qcom_scm_convention {
>   	SMC_CONVENTION_UNKNOWN,
> @@ -78,6 +79,8 @@ int scm_legacy_call_atomic(struct device *dev, const struct qcom_scm_desc *desc,
>   int scm_legacy_call(struct device *dev, const struct qcom_scm_desc *desc,
>   		    struct qcom_scm_res *res);
>   
> +struct qcom_tzmem_pool *qcom_scm_get_tzmem_pool(void);
> +
>   #define QCOM_SCM_SVC_BOOT		0x01
>   #define QCOM_SCM_BOOT_SET_ADDR		0x01
>   #define QCOM_SCM_BOOT_TERMINATE_PC	0x02