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 | 20 ++++++++++++++++++++
 include/linux/arm_ffa.h       |  3 +++
 2 files changed, 23 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index f731cc4c3f280a32acccca0de92b9ac6c8e05602..fc84595007f310004def7d525371fa7c128f244a 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -862,6 +862,22 @@ 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, flags, ctxt, 2);
+
+	struct arm_smccc_1_2_regs *args = (void *)&ctxt->regs.regs[0];
+
+	/* 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 +936,10 @@ 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 81e603839c4a51873090b7e22edbe7b33a7e94df..d209d0cdac1eb804be01e4607acac8f76cc99e40 100644
--- a/include/linux/arm_ffa.h
+++ b/include/linux/arm_ffa.h
@@ -130,6 +130,9 @@
 #define FFA_FEAT_RXTX_MIN_SZ_16K	2
 #define FFA_FEAT_RXTX_MIN_SZ_MASK	GENMASK(1, 0)
 
+/* FFA message flags */
+#define FFA_MSG_FLAGS_MSG_TYPE		BIT(31)
+
 /* FFA Bus/Device/Driver related */
 struct ffa_device {
 	u32 id;

-- 
2.52.0.457.g6b5491de43-goog

On Fri, Jan 09, 2026 at 10:34:25PM +0000, Per Larsen via B4 Relay wrote:
> 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 | 20 ++++++++++++++++++++
>  include/linux/arm_ffa.h       |  3 +++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
> index f731cc4c3f280a32acccca0de92b9ac6c8e05602..fc84595007f310004def7d525371fa7c128f244a 100644
> --- a/arch/arm64/kvm/hyp/nvhe/ffa.c
> +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
> @@ -862,6 +862,22 @@ 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, flags, ctxt, 2);
> +
> +	struct arm_smccc_1_2_regs *args = (void *)&ctxt->regs.regs[0];
> +
> +	/* 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);

I thought we were going to validate that the sender is HOST_FFA_ID?

> diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h
> index 81e603839c4a51873090b7e22edbe7b33a7e94df..d209d0cdac1eb804be01e4607acac8f76cc99e40 100644
> --- a/include/linux/arm_ffa.h
> +++ b/include/linux/arm_ffa.h
> @@ -130,6 +130,9 @@
>  #define FFA_FEAT_RXTX_MIN_SZ_16K	2
>  #define FFA_FEAT_RXTX_MIN_SZ_MASK	GENMASK(1, 0)
>  
> +/* FFA message flags */
> +#define FFA_MSG_FLAGS_MSG_TYPE		BIT(31)
> +

This hunk is no longer needed now that we're just checking for the flags
being zero.

Will