linux-kernel - [PATCH v5 6/6] KVM: arm64: Support FFA_MSG_SEND_DIRECT

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Message-Id: <20250619-virtio-msg-ffa-v5-6-412c98558807@google.com>
Date: Thu, 19 Jun 2025 09:02:59 +0000
From: Per Larsen via B4 Relay <devnull+perlarsen.google.com@...nel.org>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
 Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
 Zenghui Yu <yuzenghui@...wei.com>, 
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
 Sudeep Holla <sudeep.holla@....com>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, Per Larsen <perlarsen@...gle.com>
Subject: [PATCH v5 6/6] KVM: arm64: Support FFA_MSG_SEND_DIRECT_REQ2 in
 host handler

From: Per Larsen <perlarsen@...gle.com>

FF-A 1.2 adds the DIRECT_REQ2 messaging interface which is similar to
the existing FFA_MSG_SEND_DIRECT_{REQ,RESP} functions except that it
uses the SMC calling convention v1.2 which allows calls to use x4-x17 as
argument and return registers. Add support for FFA_MSG_SEND_DIRECT_REQ2
in the host ffa handler.

Signed-off-by: Per Larsen <perlarsen@...gle.com>
---
 arch/arm64/kvm/hyp/nvhe/ffa.c | 24 +++++++++++++++++++++++-
 include/linux/arm_ffa.h       |  2 ++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 7b43279aded7d7ef4cce2c294d208c5a66b684e3..37bde2ea2219e37ea68f859e6f211c868585285d 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -678,7 +678,6 @@ static bool ffa_call_supported(u64 func_id)
 	case FFA_NOTIFICATION_GET:
 	case FFA_NOTIFICATION_INFO_GET:
 	/* Unimplemented interfaces added in FF-A 1.2 */
-	case FFA_MSG_SEND_DIRECT_REQ2:
 	case FFA_MSG_SEND_DIRECT_RESP2:
 	case FFA_CONSOLE_LOG:
 	case FFA_PARTITION_INFO_GET_REGS:
@@ -860,6 +859,22 @@ static void do_ffa_part_get(struct arm_smccc_1_2_regs *regs,
 	hyp_spin_unlock(&host_buffers.lock);
 }
 
+static void do_ffa_direct_msg2(struct arm_smccc_1_2_regs *regs,
+			       struct kvm_cpu_context *ctxt,
+			       u64 vm_handle)
+{
+	DECLARE_REG(u32, endp, ctxt, 1);
+
+	struct arm_smccc_1_2_regs *args = (void *)&ctxt->regs.regs[0];
+
+	if (FIELD_GET(FFA_SRC_ENDPOINT_MASK, endp) != vm_handle) {
+		ffa_to_smccc_1_2_error(regs, FFA_RET_INVALID_PARAMETERS);
+		return;
+	}
+
+	arm_smccc_1_2_smc(args, regs);
+}
+
 bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
 {
 	struct arm_smccc_1_2_regs regs;
@@ -918,11 +933,18 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
 	case FFA_PARTITION_INFO_GET:
 		do_ffa_part_get(&regs, host_ctxt);
 		goto out_handled;
+	case FFA_MSG_SEND_DIRECT_REQ2:
+		if (hyp_ffa_version >= FFA_VERSION_1_2) {
+			do_ffa_direct_msg2(&regs, host_ctxt, HOST_FFA_ID);
+			goto out_handled;
+		}
+		goto out_not_supported;
 	}
 
 	if (ffa_call_supported(func_id))
 		return false; /* Pass through */
 
+out_not_supported:
 	ffa_to_smccc_1_2_error(&regs, FFA_RET_NOT_SUPPORTED);
 out_handled:
 	ffa_set_retval(host_ctxt, &regs);
diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h
index c0dd6183d956043192114a522b7eef465e7078ac..82a35a3b22de426f7e9a8894e76fdf1e933b3d6b 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 */

-- 
2.50.0.rc2.701.gf1e915cc24-goog