Re: [PATCH v9 09/10] firmware: arm_ffa: Introduce ffa-lend-pool

[Rob Herring <robh@kernel.org>]

On Wed, Sep 02, 2026 at 11:47:11AM +0100, Vincent Donnefort wrote:
> When memory is lent to the Secure world via FF-A, fatal CPU speculative
> reads from Non-Secure can still occur as long as it retains a cacheable
> mapping to that memory. Introduce the "arm,ffa-lend-pool"
> reserved-memory CMA driver to unmap pages before lending
> (ffa_prepare_lend()) and restore them upon reclaim
> (ffa_lend_reclaimed()). Devices bind to the pool via the "memory-region"
> DT property or via ffa_lend_pool_attach().
> 
>   reserved-memory {
>       #address-cells = <0x2>;
>       #size-cells = <0x2>;
>       ranges;
> 
>       ffa_lend: ffa-lend-pool {
>           compatible = "arm,ffa-lend-pool";

Needs a binding schema...

>           reusable;
>           ll-map;
>           size = <0x0 0x4000000>;
>       };
>   };
> 
> Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

[...]

> +static int __init ffa_lend_pool_setup(unsigned long node, struct reserved_mem *rmem)
> +{
> +	struct cma *cma;
> +	int ret;
> +
> +	if (!of_get_flat_dt_prop(node, "reusable", NULL) ||
> +	    of_get_flat_dt_prop(node, "no-map", NULL)) {
> +		pr_err("FF-A lend pool: node must be 'reusable' and not 'no-map'\n");
> +		return -EINVAL;

Your schema should enforce/check this.

[...]

> +static const struct reserved_mem_ops ffa_lend_pool_ops = {
> +	.node_init	= ffa_lend_pool_setup,
> +	.device_init	= ffa_lend_pool_device_init,
> +	.device_release = ffa_lend_pool_device_release,
> +};
> +RESERVEDMEM_OF_DECLARE(ffa_lend_pool, "arm,ffa-lend-pool", &ffa_lend_pool_ops);

Do you need this early? If not, you can create a platform driver for 
"arm,ffa-lend-pool". ramoops is implemented that way for example.

Rob