[PATCH v2 0/2] KVM: arm64: Support FF-A direct messaging interfaces

[PATCH v2 0/2] KVM: arm64: Support FF-A direct messaging interfaces

[Per Larsen via B4 Relay]

Support FFA_MSG_SEND_DIRECT_REQ unconditionally.
Support FFA_MSG_SEND_DIRECT_REQ2 if hypervisor negotiated version 1.2+.

The second patch was part of a previous patch set [0] but was dropped
since the use case was unclear. A clear use case has now appeared [1].

Tested by booting Android under QEMU.

Best Regards,
Per

[0]: https://lore.kernel.org/all/20250730-virtio-msg-ffa-v9-0-7f1b55c8d149@google.com/
[1]: https://lore.kernel.org/all/20251027191729.1704744-1-yeoreum.yun@arm.com/
 

Signed-off-by: Per Larsen <perlarsen@google.com>
---
Changes in v2:
- 1/2: Drop support for FFA_ID_GET interface in host handler.
- Link to v1: https://lore.kernel.org/r/20251030-host-direct-messages-v1-0-463e57871c8f@google.com

---
Per Larsen (1):
      KVM: arm64: Support FFA_MSG_SEND_DIRECT_REQ2 in host handler

Sebastian Ene (1):
      KVM: arm64: Support FFA_MSG_SEND_DIRECT_REQ in host handler

 arch/arm64/kvm/hyp/nvhe/ffa.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
---
base-commit: e53642b87a4f4b03a8d7e5f8507fc3cd0c595ea6
change-id: 20251029-host-direct-messages-5201d7f55abd

Best regards,
-- 
Per Larsen <perlarsen@google.com>

[PATCH v2 1/2] KVM: arm64: Support FFA_MSG_SEND_DIRECT_REQ in host handler

[Per Larsen via B4 Relay]

From: Sebastian Ene <sebastianene@google.com>

Allow direct messages to be forwarded from the host.

Signed-off-by: Sebastian Ene <sebastianene@google.com>
Signed-off-by: Per Larsen <perlarsen@google.com>
---
 arch/arm64/kvm/hyp/nvhe/ffa.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 4e16f9b96f637599873b16148c6e40cf1210aa3e..bb38ee7c86bad1646c16c562127eb3bef6297a84 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -857,6 +857,15 @@ 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,
+			      u64 vm_handle)
+{
+	struct arm_smccc_1_2_regs *args = (void *)&ctxt->regs.regs[0];
+
+	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;
@@ -915,6 +924,10 @@ 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, HOST_FFA_ID);
+		goto out_handled;
 	}
 
 	if (ffa_call_supported(func_id))

-- 
2.51.1.851.g4ebd6896fd-goog

[PATCH v2 2/2] KVM: arm64: Support FFA_MSG_SEND_DIRECT_REQ2 in host handler

[Per Larsen via B4 Relay]

From: Per Larsen <perlarsen@google.com>

FF-A 1.2 adds the DIRECT_REQ2 messaging interface which is similar to
the existing FFA_MSG_SEND_DIRECT_{REQ,RESP} functions and can use the
existing handler function. Add support for FFA_MSG_SEND_DIRECT_REQ2 in
the host ffa handler.

Signed-off-by: Per Larsen <perlarsen@google.com>
---
 arch/arm64/kvm/hyp/nvhe/ffa.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index bb38ee7c86bad1646c16c562127eb3bef6297a84..956c408bdae45b087286d9d35348ef599b83e392 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -678,8 +678,10 @@ static bool ffa_call_supported(u64 func_id)
 	case FFA_NOTIFICATION_SET:
 	case FFA_NOTIFICATION_GET:
 	case FFA_NOTIFICATION_INFO_GET:
+		return false;
 	/* Optional interfaces added in FF-A 1.2 */
 	case FFA_MSG_SEND_DIRECT_REQ2:		/* Optional per 7.5.1 */
+		return hyp_ffa_version >= FFA_VERSION_1_2;
 	case FFA_MSG_SEND_DIRECT_RESP2:		/* Optional per 7.5.1 */
 	case FFA_CONSOLE_LOG:			/* Optional per 13.1: not in Table 13.1 */
 	case FFA_PARTITION_INFO_GET_REGS:	/* Optional for virtual instances per 13.1 */
@@ -924,6 +926,10 @@ 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_REQ2:
+		if (!ffa_call_supported(func_id))
+			goto out_not_supported;
+		fallthrough;
 	case FFA_MSG_SEND_DIRECT_REQ:
 	case FFA_FN64_MSG_SEND_DIRECT_REQ:
 		do_ffa_direct_msg(&res, host_ctxt, HOST_FFA_ID);
@@ -933,6 +939,7 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
 	if (ffa_call_supported(func_id))
 		return false; /* Pass through */
 
+out_not_supported:
 	ffa_to_smccc_error(&res, FFA_RET_NOT_SUPPORTED);
 out_handled:
 	ffa_set_retval(host_ctxt, &res);

-- 
2.51.1.851.g4ebd6896fd-goog

Re: [PATCH v2 0/2] KVM: arm64: Support FF-A direct messaging interfaces

[Yeoreum Yun]

This series looks good to me

Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>

> Support FFA_MSG_SEND_DIRECT_REQ unconditionally.
> Support FFA_MSG_SEND_DIRECT_REQ2 if hypervisor negotiated version 1.2+.
>
> The second patch was part of a previous patch set [0] but was dropped
> since the use case was unclear. A clear use case has now appeared [1].
>
> Tested by booting Android under QEMU.
>
> Best Regards,
> Per
>
> [0]: https://lore.kernel.org/all/20250730-virtio-msg-ffa-v9-0-7f1b55c8d149@google.com/
> [1]: https://lore.kernel.org/all/20251027191729.1704744-1-yeoreum.yun@arm.com/
>
>
> Signed-off-by: Per Larsen <perlarsen@google.com>
> ---
> Changes in v2:
> - 1/2: Drop support for FFA_ID_GET interface in host handler.
> - Link to v1: https://lore.kernel.org/r/20251030-host-direct-messages-v1-0-463e57871c8f@google.com
>
> ---
> Per Larsen (1):
>       KVM: arm64: Support FFA_MSG_SEND_DIRECT_REQ2 in host handler
>
> Sebastian Ene (1):
>       KVM: arm64: Support FFA_MSG_SEND_DIRECT_REQ in host handler
>
>  arch/arm64/kvm/hyp/nvhe/ffa.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> ---
> base-commit: e53642b87a4f4b03a8d7e5f8507fc3cd0c595ea6
> change-id: 20251029-host-direct-messages-5201d7f55abd
>
> Best regards,
> --
> Per Larsen <perlarsen@google.com>
>
>

--
Sincerely,
Yeoreum Yun

Re: [PATCH v2 1/2] KVM: arm64: Support FFA_MSG_SEND_DIRECT_REQ in host handler

[Will Deacon]

On Thu, Oct 30, 2025 at 03:49:16PM +0000, Per Larsen via B4 Relay wrote:
> From: Sebastian Ene <sebastianene@google.com>
> 
> Allow direct messages to be forwarded from the host.
> 
> Signed-off-by: Sebastian Ene <sebastianene@google.com>
> Signed-off-by: Per Larsen <perlarsen@google.com>
> ---
>  arch/arm64/kvm/hyp/nvhe/ffa.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
> index 4e16f9b96f637599873b16148c6e40cf1210aa3e..bb38ee7c86bad1646c16c562127eb3bef6297a84 100644
> --- a/arch/arm64/kvm/hyp/nvhe/ffa.c
> +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
> @@ -857,6 +857,15 @@ 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,
> +			      u64 vm_handle)
> +{
> +	struct arm_smccc_1_2_regs *args = (void *)&ctxt->regs.regs[0];
> +
> +	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;
> @@ -915,6 +924,10 @@ 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, HOST_FFA_ID);
> +		goto out_handled;

Should we filter out framework messages so that this is limited to partition
messages instead?

Will