Re: [PATCH] tee: amdtee: add support for use of cma region

[Randy Dunlap]

Hi--

On 8/18/23 07:42, Devaraj Rangasamy wrote:
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 722b6eca2e93..5e38423f3d53 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -363,6 +363,13 @@
>  			  selects a performance level in this range and appropriate
>  			  to the current workload.
>  
> +	amdtee_cma=nn	[HW,TEE]
> +			Sets the memory size reserved for contiguous memory
> +			allocations, to be used by amdtee device driver.
> +			Value is in MB and can range from 4 to 128 (MBs)

			                                       128 (MBs).

> +			CMA will be active only when CMA is enabled, and amdtee is

	That could use some improvement. How about:

			AMD-TEE CMA will be active only when CONFIG_CMA is enabled,
			and amdtee is

> +			built as inbuilt driver, and not loaded as module.
> +
>  	amijoy.map=	[HW,JOY] Amiga joystick support
>  			Map of devices attached to JOY0DAT and JOY1DAT
>  			Format: <a>,<b>

> diff --git a/drivers/tee/amdtee/Kconfig b/drivers/tee/amdtee/Kconfig
> index 191f9715fa9a..5843c739a7b8 100644
> --- a/drivers/tee/amdtee/Kconfig
> +++ b/drivers/tee/amdtee/Kconfig
> @@ -6,3 +6,12 @@ config AMDTEE
>  	depends on CRYPTO_DEV_SP_PSP && CRYPTO_DEV_CCP_DD
>  	help
>  	  This implements AMD's Trusted Execution Environment (TEE) driver.
> +
> +config AMDTEE_CMA_SIZE
> +	int "Size of Memory in MiB reserved in CMA for AMD-TEE"
> +	default "0"

Why won't this default value cause an allocation error message?
Maybe I'm just not following the call paths correctly.

It looks to me like this causes a call to
cma_declare_contiguous_nid() with @size = 0, and that function says:

	if (!size)
		return -EINVAL;

> +	depends on CMA && (AMDTEE=y)
> +	help
> +	  Specify the default amount of memory in MiB reserved in CMA for AMD-TEE driver

	                                                                          driver.

> +	  Any amdtee shm buffer allocation larger than 64k will allocate memory from the CMA

	                                                                                 CMA.

> +	  The default can be overridden with the kernel commandline parameter "amdtee_cma".
> \ No newline at end of file

Please fix that ^^^ warning.

Thanks.
-- 
~Randy