[PATCH v7 5/7] KVM: arm64: Support FFA_NOTIFICATION_GET in host handler

[Sebastian Ene <sebastianene@google.com>]

Allow FF-A notification GET messages to be proxied from the pKVM
hypervisor to Trustzone and verify the arguments sent from the host
driver.

Signed-off-by: Sebastian Ene <sebastianene@google.com>
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
---
 arch/arm64/kvm/hyp/nvhe/ffa.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 2bb16aa414f9..c22fe4514741 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -679,7 +679,6 @@ 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 */
@@ -938,6 +937,27 @@ static void do_ffa_notif_set(struct arm_smccc_1_2_regs *res,
 	hyp_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, endp_id, ctxt, 1);
+	DECLARE_REG(u32, flags, ctxt, 2);
+	struct arm_smccc_1_2_regs *args;
+
+	if (FIELD_GET(FFA_NOTIF_RECEIVER_ENDP_MASK, endp_id) != HOST_FFA_ID) {
+		ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS);
+		return;
+	}
+
+	if (flags & GENMASK(31, 4)) {
+		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;
@@ -1009,6 +1029,9 @@ 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))
-- 
2.55.0.rc0.799.gd6f94ed593-goog