Re: [PATCH v3 6/7] KVM: arm64: Support FFA_NOTIFICATION_GET in host handler

[Vincent Donnefort <vdonnefort@google.com>]

On Tue, Jun 16, 2026 at 10:54:15AM +0000, Sebastian Ene wrote:
> Allow FF-A notification GET messages to be proxied from the pKVM
> hypervisor to Trustzone and enforce MBZ/SBZ fields.
> 
> Signed-off-by: Sebastian Ene <sebastianene@google.com>
> ---
>  arch/arm64/kvm/hyp/nvhe/ffa.c | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
> index fcfaa441770d..549250ff8f82 100644
> --- a/arch/arm64/kvm/hyp/nvhe/ffa.c
> +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
> @@ -715,7 +715,6 @@ 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_GET:
>  	case FFA_NOTIFICATION_INFO_GET:
>  	/* Optional interfaces added in FF-A 1.2 */
>  	case FFA_MSG_SEND_DIRECT_REQ2:		/* Optional per 7.5.1 */
> @@ -1001,6 +1000,26 @@ static void do_ffa_notif_set(struct arm_smccc_1_2_regs *res,
>  	arm_smccc_1_2_smc(args, res);
>  }
>  
> +static void do_ffa_notif_get(struct arm_smccc_1_2_regs *res,
> +			     struct kvm_cpu_context *ctxt)
> +{
> +	DECLARE_REG(u32, flags, ctxt, 2);
> +	struct arm_smccc_1_2_regs *args;
> +
> +	if (ffa_check_unused_args_sbz(ctxt, 3)) {
> +		ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS);
> +		return;
> +	}

Shall we check that the endpoint ID is HOST_FFA_ID here?

> +
> +	if (flags & GENMASK(31, 4)) {
> +		ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS);
> +		return;
> +	}
> +
> +	args = (void *)&ctxt->regs.regs[0];
> +	arm_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;
> @@ -1072,6 +1091,9 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
>  	case FFA_NOTIFICATION_SET:
>  		do_ffa_notif_set(&res, host_ctxt);
>  		goto out_handled;
> +	case FFA_NOTIFICATION_GET:
> +		do_ffa_notif_get(&res, host_ctxt);
> +		goto out_handled;
>  	}
>  
>  	if (ffa_call_supported(func_id))
> -- 
> 2.54.0.1136.gdb2ca164c4-goog
>