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

[Sebastian Ene <sebastianene@google.com>]

On Tue, Jun 16, 2026 at 02:26:58PM +0100, Vincent Donnefort wrote:
> 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?
> 

Yes we can add this check

> > +
> > +	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
> >