Re: [PATCH v3 3/7] KVM: arm64: Support FFA_NOTIFICATION_BIND in host handler

[Sebastian Ene <sebastianene@google.com>]

On Tue, Jun 16, 2026 at 02:06:12PM +0100, Vincent Donnefort wrote:
> On Tue, Jun 16, 2026 at 10:54:12AM +0000, Sebastian Ene wrote:
> > Verify the arguments of the FF-A notification bind call and forward the
> > message to Trustzone.
> > 
> > Signed-off-by: Sebastian Ene <sebastianene@google.com>
> > ---
> >  arch/arm64/kvm/hyp/nvhe/ffa.c | 32 +++++++++++++++++++++++++++++++-
> >  1 file changed, 31 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
> > index dc7496ec295f..3d8ed829f558 100644
> > --- a/arch/arm64/kvm/hyp/nvhe/ffa.c
> > +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
> > @@ -42,6 +42,8 @@
> >   */
> >  #define HOST_FFA_ID	0
> >  
> > +#define FFA_NOTIF_SENDER_ENDP_MASK	GENMASK(31, 16)
> > +
> >  /*
> >   * A buffer to hold the maximum descriptor size we can see from the host,
> >   * which is required when the SPMD returns a fragmented FFA_MEM_RETRIEVE_RESP
> > @@ -713,7 +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_BIND:
> >  	case FFA_NOTIFICATION_UNBIND:
> >  	case FFA_NOTIFICATION_SET:
> >  	case FFA_NOTIFICATION_GET:
> > @@ -929,6 +930,32 @@ static void do_ffa_notif_bitmap(struct arm_smccc_1_2_regs *res,
> >  	hyp_smccc_1_2_smc(args, res);
> >  }
> >  
> > +static void do_ffa_notif_bind(struct arm_smccc_1_2_regs *res,
> > +			      struct kvm_cpu_context *ctxt)
> > +{
> > +	DECLARE_REG(u32, endp_id, ctxt, 1);
> > +	DECLARE_REG(u32, flags, ctxt, 2);
> > +	struct arm_smccc_1_2_regs *args;
> > +
> > +	if (ffa_check_unused_args_sbz(ctxt, 5)) {
> > +		ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS);
> > +		return;
> > +	}
> > +
> > +	if (FIELD_GET(FFA_NOTIF_SENDER_ENDP_MASK, endp_id) != HOST_FFA_ID) {
> 
> "A Receiver uses the FFA_NOTIFICATION_BIND interface to bind one or more
> notifications to the Sender"
> 
> Does that mean that if the host issues a FFA_NOTIFICATION_BIND it is the
> "Receiver" and not the "Sender"? 
> 
> (Same for unbind)
> 

This means that we will have to check the ID of the receiver and not the
sender. Thanks for pointing out, I will add this to unbind as well.

> 
> > +		ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS);
> > +		return;
> > +	}
> > +
> > +	if (flags > 1) {
> > +		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;
> > @@ -991,6 +1018,9 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
> >  	case FFA_NOTIFICATION_BITMAP_DESTROY:
> >  		do_ffa_notif_bitmap(&res, host_ctxt);
> >  		goto out_handled;
> > +	case FFA_NOTIFICATION_BIND:
> > +		do_ffa_notif_bind(&res, host_ctxt);
> > +		goto out_handled;
> >  	}
> >  
> >  	if (ffa_call_supported(func_id))
> > -- 
> > 2.54.0.1136.gdb2ca164c4-goog
> > 

Sebastian