[PATCH v4 5/7] KVM: arm64: Support FFA_NOTIFICATION_SET in host handler

[Sebastian Ene <sebastianene@google.com>]

Allow FF-A notification SET 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 | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index adf8680f3266..fdf1e5fb6726 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -43,6 +43,7 @@
 #define HOST_FFA_ID	0
 
 #define FFA_NOTIF_RECEIVER_ENDP_MASK	GENMASK(15, 0)
+#define FFA_NOTIF_SENDER_ENDP_MASK	GENMASK(31, 16)
 
 /*
  * A buffer to hold the maximum descriptor size we can see from the host,
@@ -715,7 +716,6 @@ 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_SET:
 	case FFA_NOTIFICATION_GET:
 	case FFA_NOTIFICATION_INFO_GET:
 	/* Optional interfaces added in FF-A 1.2 */
@@ -975,6 +975,32 @@ static void do_ffa_notif_unbind(struct arm_smccc_1_2_regs *res,
 	hyp_smccc_1_2_smc(args, res);
 }
 
+static void do_ffa_notif_set(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_SENDER_ENDP_MASK, endp_id) != HOST_FFA_ID) {
+		ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS);
+		return;
+	}
+
+	if (ffa_check_unused_args_sbz(ctxt, 5)) {
+		ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS);
+		return;
+	}
+
+	if (flags & GENMASK(15, 2)) {
+		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;
@@ -1043,6 +1069,9 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
 	case FFA_NOTIFICATION_UNBIND:
 		do_ffa_notif_unbind(&res, host_ctxt);
 		goto out_handled;
+	case FFA_NOTIFICATION_SET:
+		do_ffa_notif_set(&res, host_ctxt);
+		goto out_handled;
 	}
 
 	if (ffa_call_supported(func_id))
-- 
2.54.0.1136.gdb2ca164c4-goog