Re: [PATCH v3 2/7] KVM: arm64: Forward FFA_NOTIFICATION_BITMAP calls to Trustzone

[Vincent Donnefort <vdonnefort@google.com>]

On Tue, Jun 16, 2026 at 10:54:10AM +0000, Sebastian Ene wrote:
> Allow FF-A notification bitmap messages to be forwarded to
> Trustzone from the host kernel driver enforce checking for
> SBZ fields.
> 
> Signed-off-by: Sebastian Ene <sebastianene@google.com>
> ---
>  arch/arm64/kvm/hyp/nvhe/ffa.c | 28 ++++++++++++++++++++++++++--
>  1 file changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
> index c723a21006aa..dc7496ec295f 100644
> --- a/arch/arm64/kvm/hyp/nvhe/ffa.c
> +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
> @@ -713,8 +713,6 @@ static bool ffa_call_supported(u64 func_id)
>  	case FFA_MEM_DONATE:
>  	case FFA_MEM_RETRIEVE_REQ:
>         /* Optional notification interfaces added in FF-A 1.1 */
> -	case FFA_NOTIFICATION_BITMAP_CREATE:
> -	case FFA_NOTIFICATION_BITMAP_DESTROY:
>  	case FFA_NOTIFICATION_BIND:
>  	case FFA_NOTIFICATION_UNBIND:
>  	case FFA_NOTIFICATION_SET:
> @@ -909,6 +907,28 @@ static void do_ffa_part_get(struct arm_smccc_1_2_regs *res,
>  	hyp_spin_unlock(&host_buffers.lock);
>  }
>  
> +static void do_ffa_notif_bitmap(struct arm_smccc_1_2_regs *res,
> +				struct kvm_cpu_context *ctxt)
> +{
> +	DECLARE_REG(u32, func_id, ctxt, 0);
> +	DECLARE_REG(u32, vmid, ctxt, 1);
> +	struct arm_smccc_1_2_regs *args;
> +	u32 idx_unused_args = func_id == FFA_NOTIFICATION_BITMAP_CREATE ? 3 : 2;

nit: should probably better expressed as a int as this is the type in the
ffa_check_unused_args_sbz proto.

Perhaps you can even fold that directly into the ffa_check_unused_args_sbz()
call?

> +
> +	if (ffa_check_unused_args_sbz(ctxt, idx_unused_args)) {
> +		ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS);
> +		return;
> +	}
> +
> +	if (vmid != HOST_FFA_ID) {
> +		ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS);
> +		return;
> +	}
> +
> +	args = (void *)&ctxt->regs.regs[0];
> +	hyp_smccc_1_2_smc(args, res);
> +}
> +
>  bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
>  {
>  	struct arm_smccc_1_2_regs res;
> @@ -967,6 +987,10 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
>  	case FFA_PARTITION_INFO_GET:
>  		do_ffa_part_get(&res, host_ctxt);
>  		goto out_handled;
> +	case FFA_NOTIFICATION_BITMAP_CREATE:
> +	case FFA_NOTIFICATION_BITMAP_DESTROY:
> +		do_ffa_notif_bitmap(&res, host_ctxt);
> +		goto out_handled;
>  	}
>  
>  	if (ffa_call_supported(func_id))
> -- 
> 2.54.0.1136.gdb2ca164c4-goog
>