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

[Vincent Donnefort <vdonnefort@google.com>]

On Wed, Sep 02, 2026 at 12:38:26PM -0500, Rob Herring wrote:
> 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...

Ack

> 
> >           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

Only memblock_mark_llmap() must be called very early.

The rest just need to be in place before the TEE driver probed. So a platform
driver should work.

Thanks!

-- 
Vincent