[PATCH v6 1/2] KVM: arm64: Support FFA_MSG_SEND_DIRECT_REQ in host handler

[Per Larsen via B4 Relay <devnull+perlarsen.google.com@kernel.org>]

From: Sebastian Ene <sebastianene@google.com>

Allow direct messages to be forwarded from the host. The host should
not be sending framework messages so they are filtered out.

Signed-off-by: Sebastian Ene <sebastianene@google.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Signed-off-by: Per Larsen <perlarsen@google.com>
---
 arch/arm64/kvm/hyp/nvhe/ffa.c | 26 ++++++++++++++++++++++++++
 include/linux/arm_ffa.h       |  2 ++
 2 files changed, 28 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 1af722771178..3a58e01d255f 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -862,6 +862,28 @@ static void do_ffa_part_get(struct arm_smccc_1_2_regs *res,
 	hyp_spin_unlock(&host_buffers.lock);
 }
 
+static void do_ffa_direct_msg(struct arm_smccc_1_2_regs *res,
+			      struct kvm_cpu_context *ctxt)
+{
+	DECLARE_REG(u32, endp, ctxt, 1);
+	DECLARE_REG(u32, flags, ctxt, 2);
+
+	struct arm_smccc_1_2_regs *args = (void *)&ctxt->regs.regs[0];
+
+	if (FIELD_GET(FFA_SRC_ENDPOINT_MASK, endp) != HOST_FFA_ID) {
+		ffa_to_smccc_error(res, FFA_RET_INVALID_PARAMETERS);
+		return;
+	}
+
+	/* filter out framework messages and validate SBZ/MBZ bits */
+	if (flags) {
+		ffa_to_smccc_error(res, FFA_RET_INVALID_PARAMETERS);
+		return;
+	}
+
+	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;
@@ -920,6 +942,10 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
 	case FFA_PARTITION_INFO_GET:
 		do_ffa_part_get(&res, host_ctxt);
 		goto out_handled;
+	case FFA_MSG_SEND_DIRECT_REQ:
+	case FFA_FN64_MSG_SEND_DIRECT_REQ:
+		do_ffa_direct_msg(&res, host_ctxt);
+		goto out_handled;
 	}
 
 	if (ffa_call_supported(func_id))
diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h
index 81e603839c4a..f47d4bd51b2d 100644
--- a/include/linux/arm_ffa.h
+++ b/include/linux/arm_ffa.h
@@ -269,6 +269,8 @@ bool ffa_partition_check_property(struct ffa_device *dev, u32 property)
 	(ffa_partition_check_property(dev, FFA_PARTITION_DIRECT_REQ2_RECV) && \
 	 !dev->mode_32bit)
 
+#define FFA_SRC_ENDPOINT_MASK	GENMASK(31, 16)
+
 /* For use with FFA_MSG_SEND_DIRECT_{REQ,RESP} which pass data via registers */
 struct ffa_send_direct_data {
 	unsigned long data0; /* w3/x3 */

-- 
2.54.0.545.g6539524ca2-goog