[PATCH 0/2] ACPI: Arm FFH: Add support for OpRegion Offset 2 (FF-A DIRECT_REQ2)

[PATCH 0/2] ACPI: Arm FFH: Add support for OpRegion Offset 2 (FF-A DIRECT_REQ2)

[Sudeep Holla]

Hi,

This patch series extends the existing Linux kernel ACPI Functional Fixed
Hardware (FFH) Operation Region support to accommodate FFH Operation Region
Offset 2, as introduced in the Arm Functional Fixed Hardware Specification
v1.3.

Background
----------

The Arm FFH Specification v1.3 adds support for FFH Operation Region Offset 2.
An OpRegion declared with an offset of 2 triggers an FFA_MSG_SEND_DIRECT_REQ2
call instead of using legacy SMC/HVC or standard DIRECT_REQ variants.
This mechanism allows the platform's ACPI firmware to interact directly
with secure partitions by evaluating a service UUID.

Implementation
--------------
- Upgrades the arm64 low-level FFH handler beyond generic SMCCC calls to
  natively support the FF-A protocol. It negotiates FF-A v1.2, identifies
  sender endpoints via FFA_ID_GET, translates ACPI ToUUID properties to
  register formats, handles interrupted/yielded calls via FFA_RUN, and
  returns standard FFH status codes to AML.
- Leverages register-based endpoint discovery (FFA_PARTITION_INFO_GET_REGS)
  to resolve unique receivers from service UUIDs. This approach completely
  avoids RX/TX memory buffer ownership complexities, keeping the low-level
  ACPI FFH subsystem cleanly decoupled from the main Arm FF-A transport
  driver.

Sudeep Holla (2):
  firmware: arm_ffa: Share FF-A register field definitions
  ACPI: FFH: Support FF-A direct request 2 calls

 drivers/acpi/arm64/ffh.c          | 227 ++++++++++++++++++++++++++++++
 drivers/firmware/arm_ffa/driver.c |  48 +++----
 include/linux/arm_ffa.h           |  19 +++
 3 files changed, 263 insertions(+), 31 deletions(-)

-- 
2.43.0

[PATCH 1/2] firmware: arm_ffa: Share FF-A register field definitions

[Sudeep Holla]

ACPI FFH and the FF-A transport driver interpret the same
PARTITION_INFO_GET_REGS metadata and pack endpoint IDs using the same
bit fields. Define these fields once in arm_ffa.h instead of keeping
private copies.

Use the shared masks in the transport driver and check descriptor
lengths against the same minimum used by ACPI FFH. This keeps the ABI
encoding consistent between the two users.

Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>
---
 drivers/firmware/arm_ffa/driver.c | 48 +++++++++++--------------------
 include/linux/arm_ffa.h           | 19 ++++++++++++
 2 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index 28abc808fd32..babc5d62bdd2 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -52,13 +52,6 @@
 #define FFA_MIN_VERSION		FFA_VERSION_1_0
 #define FFA_PLATFORM_NAME	"arm-ffa"
 
-#define SENDER_ID_MASK		GENMASK(31, 16)
-#define RECEIVER_ID_MASK	GENMASK(15, 0)
-#define SENDER_ID(x)		((u16)(FIELD_GET(SENDER_ID_MASK, (x))))
-#define RECEIVER_ID(x)		((u16)(FIELD_GET(RECEIVER_ID_MASK, (x))))
-#define PACK_TARGET_INFO(s, r)		\
-	(FIELD_PREP(SENDER_ID_MASK, (s)) | FIELD_PREP(RECEIVER_ID_MASK, (r)))
-
 #define RXTX_MAP_MIN_BUFSZ_MASK	GENMASK(1, 0)
 #define RXTX_MAP_MAX_BUFSZ_MASK	GENMASK(31, 16)
 #define RXTX_MAP_MIN_BUFSZ(x)	(FIELD_GET(RXTX_MAP_MIN_BUFSZ_MASK, (x)))
@@ -320,24 +313,16 @@ __ffa_partition_info_get(u32 uuid0, u32 uuid1, u32 uuid2, u32 uuid3,
 	return count;
 }
 
-#define LAST_INDEX_MASK		GENMASK(15, 0)
-#define CURRENT_INDEX_MASK	GENMASK(31, 16)
-#define UUID_INFO_TAG_MASK	GENMASK(47, 32)
-#define PARTITION_INFO_SZ_MASK	GENMASK(63, 48)
-#define PARTITION_COUNT(x)	((u16)(FIELD_GET(LAST_INDEX_MASK, (x))) + 1)
-#define CURRENT_INDEX(x)	((u16)(FIELD_GET(CURRENT_INDEX_MASK, (x))))
-#define UUID_INFO_TAG(x)	((u16)(FIELD_GET(UUID_INFO_TAG_MASK, (x))))
-#define PARTITION_INFO_SZ(x)	((u16)(FIELD_GET(PARTITION_INFO_SZ_MASK, (x))))
-#define PART_INFO_ID_MASK	GENMASK(15, 0)
-#define PART_INFO_EXEC_CXT_MASK	GENMASK(31, 16)
-#define PART_INFO_PROPS_MASK	GENMASK(63, 32)
+#define PARTITION_COUNT(x)	((u16)(FIELD_GET(FFA_PART_INFO_LAST_IDX_MASK, (x))) + 1)
+#define CURRENT_INDEX(x)	((u16)(FIELD_GET(FFA_PART_INFO_CUR_IDX_MASK, (x))))
+#define UUID_INFO_TAG(x)	((u16)(FIELD_GET(FFA_PART_INFO_UUID_TAG_MASK, (x))))
+#define PARTITION_INFO_SZ(x)	((u16)(FIELD_GET(FFA_PART_INFO_DESC_SIZE_MASK, (x))))
 #define FFA_PART_INFO_GET_REGS_FIRST_REG	3
-#define FFA_PART_INFO_GET_REGS_MIN_REGS_PER_DESC	3
 #define FFA_PART_INFO_GET_REGS_NUM_REGS \
 	(sizeof(ffa_value_t) / sizeof_field(ffa_value_t, a0))
-#define PART_INFO_ID(x)		((u16)(FIELD_GET(PART_INFO_ID_MASK, (x))))
-#define PART_INFO_EXEC_CXT(x)	((u16)(FIELD_GET(PART_INFO_EXEC_CXT_MASK, (x))))
-#define PART_INFO_PROPERTIES(x)	((u32)(FIELD_GET(PART_INFO_PROPS_MASK, (x))))
+#define PART_INFO_ID(x)		((u16)(FIELD_GET(FFA_PART_INFO_ID_MASK, (x))))
+#define PART_INFO_EXEC_CXT(x)	((u16)(FIELD_GET(FFA_PART_INFO_EXEC_CXT_MASK, (x))))
+#define PART_INFO_PROPERTIES(x)	((u32)(FIELD_GET(FFA_PART_INFO_PROPS_MASK, (x))))
 static int
 __ffa_partition_info_get_regs(u32 uuid0, u32 uuid1, u32 uuid2, u32 uuid3,
 			      struct ffa_partition_info *buffer, int num_parts)
@@ -375,9 +360,9 @@ __ffa_partition_info_get_regs(u32 uuid0, u32 uuid1, u32 uuid2, u32 uuid3,
 		if (buf_sz % sizeof(*regs))
 			return -EINVAL;
 
-		regs_per_desc = buf_sz / sizeof(*regs);
-		if (regs_per_desc < FFA_PART_INFO_GET_REGS_MIN_REGS_PER_DESC)
+		if (buf_sz < FFA_PART_INFO_MIN_DESC_SIZE)
 			return -EINVAL;
+		regs_per_desc = buf_sz / sizeof(*regs);
 
 		nr_desc = cur_idx - start_idx + 1;
 		max_desc = (FFA_PART_INFO_GET_REGS_NUM_REGS -
@@ -493,7 +478,7 @@ static inline void ffa_msg_send_wait_for_completion(ffa_value_t *ret)
 static int ffa_msg_send_direct_req(u16 src_id, u16 dst_id, bool mode_32bit,
 				   struct ffa_send_direct_data *data)
 {
-	u32 req_id, resp_id, src_dst_ids = PACK_TARGET_INFO(src_id, dst_id);
+	u32 req_id, resp_id, src_dst_ids = ffa_pack_target_info(src_id, dst_id);
 	ffa_value_t ret;
 
 	if (mode_32bit) {
@@ -529,7 +514,7 @@ static int ffa_msg_send_direct_req(u16 src_id, u16 dst_id, bool mode_32bit,
 
 static int ffa_msg_send2(struct ffa_device *dev, u16 src_id, void *buf, size_t sz)
 {
-	u32 src_dst_ids = PACK_TARGET_INFO(src_id, dev->vm_id);
+	u32 src_dst_ids = ffa_pack_target_info(src_id, dev->vm_id);
 	struct ffa_indirect_msg_hdr *msg;
 	ffa_value_t ret;
 	int retval = 0;
@@ -563,7 +548,7 @@ static int ffa_msg_send2(struct ffa_device *dev, u16 src_id, void *buf, size_t s
 static int ffa_msg_send_direct_req2(u16 src_id, u16 dst_id, const uuid_t *uuid,
 				    struct ffa_send_direct_data2 *data)
 {
-	u32 src_dst_ids = PACK_TARGET_INFO(src_id, dst_id);
+	u32 src_dst_ids = ffa_pack_target_info(src_id, dst_id);
 	union {
 		uuid_t uuid;
 		__le64 regs[2];
@@ -889,7 +874,7 @@ enum notify_type {
 #define RECEIVER_VCPU_MASK		GENMASK(31, 16)
 #define PACK_NOTIFICATION_GET_RECEIVER_INFO(vcpu_r, r) \
 	(FIELD_PREP(RECEIVER_VCPU_MASK, (vcpu_r)) | \
-	 FIELD_PREP(RECEIVER_ID_MASK, (r)))
+	 FIELD_PREP(FFA_TARGET_INFO_RECEIVER_MASK, (r)))
 
 #define NOTIFICATION_INFO_GET_MORE_PEND_MASK	BIT(0)
 #define NOTIFICATION_INFO_GET_ID_COUNT		GENMASK(11, 7)
@@ -920,7 +905,7 @@ static int ffa_notification_bind_common(u16 dst_id, u64 bitmap,
 					u32 flags, bool is_bind)
 {
 	ffa_value_t ret;
-	u32 func, src_dst_ids = PACK_TARGET_INFO(dst_id, drv_info->vm_id);
+	u32 func, src_dst_ids = ffa_pack_target_info(dst_id, drv_info->vm_id);
 
 	func = is_bind ? FFA_NOTIFICATION_BIND : FFA_NOTIFICATION_UNBIND;
 
@@ -942,7 +927,7 @@ static
 int ffa_notification_set(u16 src_id, u16 dst_id, u32 flags, u64 bitmap)
 {
 	ffa_value_t ret;
-	u32 src_dst_ids = PACK_TARGET_INFO(dst_id, src_id);
+	u32 src_dst_ids = ffa_pack_target_info(dst_id, src_id);
 
 	invoke_ffa_fn((ffa_value_t) {
 		  .a0 = FFA_NOTIFICATION_SET, .a1 = src_dst_ids, .a2 = flags,
@@ -1542,7 +1527,8 @@ static void handle_fwk_notif_callbacks(u32 bitmap)
 			return;
 		}
 
-		target = SENDER_ID(msg->send_recv_id);
+		target = FIELD_GET(FFA_TARGET_INFO_SENDER_MASK,
+				   msg->send_recv_id);
 		if (offset >= sizeof(*msg))
 			uuid_copy(&uuid, &msg->uuid);
 		else
diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h
index e71d83ee0aef..3831fbe244c1 100644
--- a/include/linux/arm_ffa.h
+++ b/include/linux/arm_ffa.h
@@ -130,6 +130,15 @@
 #define FFA_FEAT_RXTX_MIN_SZ_16K	2
 #define FFA_FEAT_RXTX_MIN_SZ_MASK	GENMASK(1, 0)
 
+#define FFA_TARGET_INFO_SENDER_MASK	GENMASK(31, 16)
+#define FFA_TARGET_INFO_RECEIVER_MASK	GENMASK(15, 0)
+
+static inline u32 ffa_pack_target_info(u16 sender, u16 receiver)
+{
+	return FIELD_PREP(FFA_TARGET_INFO_SENDER_MASK, sender) |
+	       FIELD_PREP(FFA_TARGET_INFO_RECEIVER_MASK, receiver);
+}
+
 /* FFA Bus/Device/Driver related */
 struct ffa_device {
 	u32 id;
@@ -228,6 +237,16 @@ extern const struct bus_type ffa_bus_type;
 /* The FF-A 1.0 partition structure lacks the uuid[4] */
 #define FFA_1_0_PARTITON_INFO_SZ	(8)
 
+/* FFA_PARTITION_INFO_GET_REGS response fields */
+#define FFA_PART_INFO_LAST_IDX_MASK	GENMASK_ULL(15, 0)
+#define FFA_PART_INFO_CUR_IDX_MASK	GENMASK_ULL(31, 16)
+#define FFA_PART_INFO_UUID_TAG_MASK	GENMASK_ULL(47, 32)
+#define FFA_PART_INFO_DESC_SIZE_MASK	GENMASK_ULL(63, 48)
+#define FFA_PART_INFO_MIN_DESC_SIZE	24
+#define FFA_PART_INFO_ID_MASK		GENMASK_ULL(15, 0)
+#define FFA_PART_INFO_EXEC_CXT_MASK	GENMASK_ULL(31, 16)
+#define FFA_PART_INFO_PROPS_MASK		GENMASK_ULL(63, 32)
+
 /* FFA transport related */
 struct ffa_partition_info {
 	u16 id;
-- 
2.43.0

[PATCH 2/2] ACPI: FFH: Support FF-A direct request 2 calls

[Sudeep Holla]

Arm Functional Fixed Hardware specification v1.3 defines FFH
OperationRegion offset 2 for issuing FFA_MSG_SEND_DIRECT_REQ2 calls.
The arm64 FFH handler currently supports only generic 32-bit and 64-bit
SMCCC calls, so it cannot implement this standardized interface.

Add a standalone FF-A path using the existing SMCCC conduit. Negotiate
FF-A v1.2, discover the sender endpoint with FFA_ID_GET, and use either
the receiver supplied by firmware or resolve a unique receiver from the
service UUID with FFA_PARTITION_INFO_GET_REGS.

Convert the ACPI ToUUID representation to the FF-A register encoding,
construct the direct request, resume interrupted or yielded calls with
FFA_RUN, and return the defined FFH status codes to AML.

Register-based partition discovery avoids RX/TX buffer ownership and
keeps the FFH implementation independent of the Arm FF-A transport
driver.

Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>
---
 drivers/acpi/arm64/ffh.c | 227 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 227 insertions(+)

diff --git a/drivers/acpi/arm64/ffh.c b/drivers/acpi/arm64/ffh.c
index 04380bab193d..3f8cecc8ab22 100644
--- a/drivers/acpi/arm64/ffh.c
+++ b/drivers/acpi/arm64/ffh.c
@@ -1,7 +1,22 @@
 // SPDX-License-Identifier: GPL-2.0-only
 #include <linux/acpi.h>
+#include <linux/arm_ffa.h>
 #include <linux/arm-smccc.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
 #include <linux/slab.h>
+#include <linux/unaligned.h>
+
+#define FFH_FFA_CALL_FAILED		1
+#define FFH_FFA_SUCCESS			0
+#define FFH_FFA_NOT_SUPPORTED		-1
+#define FFH_FFA_INVALID_PARAMETERS	-2
+#define FFH_FFA_OUT_OF_MEMORY		-3
+#define FFH_FFA_UNSPECIFIED_ERROR	-4
+
+#define FFH_FFA_MIN_LEN			(5 * sizeof(u64))
+#define FFH_FFA_MAX_LEN			(18 * sizeof(u64))
+#define FFH_FFA_UUID_OFFSET		(2 * sizeof(u64))
 
 /*
  * Implements ARM64 specific callbacks to support ACPI FFH Operation Region as
@@ -19,6 +34,216 @@ struct acpi_ffh_data {
 				struct arm_smccc_1_2_regs *res);
 };
 
+static DEFINE_MUTEX(acpi_ffh_ffa_lock);
+static bool acpi_ffh_ffa_version_negotiated;
+static bool acpi_ffh_ffa_initialized;
+static u16 acpi_ffh_ffa_sender_id;
+
+static void acpi_ffh_ffa_invoke(struct acpi_ffh_data *ffh_ctxt,
+				const struct arm_smccc_1_2_regs *args,
+				struct arm_smccc_1_2_regs *res)
+{
+	ffh_ctxt->invoke_ffh64_fn(args, res);
+}
+
+static int acpi_ffh_ffa_features(struct acpi_ffh_data *ffh_ctxt, u32 fid)
+{
+	struct arm_smccc_1_2_regs args = {
+		.a0 = FFA_FEATURES,
+		.a1 = fid,
+	};
+	struct arm_smccc_1_2_regs res;
+
+	acpi_ffh_ffa_invoke(ffh_ctxt, &args, &res);
+	if (res.a0 == FFA_ERROR) {
+		if ((s32)res.a2 == FFA_RET_NOT_SUPPORTED)
+			return -EOPNOTSUPP;
+		return -EINVAL;
+	}
+
+	return res.a0 == FFA_SUCCESS ? 0 : -EIO;
+}
+
+static int acpi_ffh_ffa_init(struct acpi_ffh_data *ffh_ctxt)
+{
+	struct arm_smccc_1_2_regs args = { }, res;
+	u32 version;
+	int ret = 0;
+
+	mutex_lock(&acpi_ffh_ffa_lock);
+	if (acpi_ffh_ffa_initialized)
+		goto out;
+
+	if (!acpi_ffh_ffa_version_negotiated) {
+		args.a0 = FFA_VERSION;
+		args.a1 = FFA_VERSION_1_2;
+		acpi_ffh_ffa_invoke(ffh_ctxt, &args, &res);
+		version = res.a0;
+		if ((s32)version == SMCCC_RET_NOT_SUPPORTED ||
+		    FFA_MAJOR_VERSION(version) != 1 ||
+		    version < FFA_VERSION_1_2) {
+			ret = -EOPNOTSUPP;
+			goto out;
+		}
+		acpi_ffh_ffa_version_negotiated = true;
+	}
+
+	ret = acpi_ffh_ffa_features(ffh_ctxt, FFA_MSG_SEND_DIRECT_REQ2);
+	if (ret)
+		goto out;
+
+	ret = acpi_ffh_ffa_features(ffh_ctxt, FFA_MSG_SEND_DIRECT_RESP2);
+	if (ret)
+		goto out;
+
+	ret = acpi_ffh_ffa_features(ffh_ctxt, FFA_PARTITION_INFO_GET_REGS);
+	if (ret)
+		goto out;
+
+	args = (struct arm_smccc_1_2_regs) { .a0 = FFA_ID_GET };
+	acpi_ffh_ffa_invoke(ffh_ctxt, &args, &res);
+	if (res.a0 == FFA_ERROR) {
+		ret = (s32)res.a2 == FFA_RET_NOT_SUPPORTED ?
+		      -EOPNOTSUPP : -EIO;
+		goto out;
+	}
+	if (res.a0 != FFA_SUCCESS) {
+		ret = -EIO;
+		goto out;
+	}
+
+	acpi_ffh_ffa_sender_id = (u16)res.a2;
+	acpi_ffh_ffa_initialized = true;
+out:
+	mutex_unlock(&acpi_ffh_ffa_lock);
+	return ret;
+}
+
+static void acpi_ffh_ffa_uuid_convert(const u8 *guid, u8 *uuid)
+{
+	/* ACPI ToUUID uses GUID byte order while FF-A uses UUID byte order. */
+	uuid[0] = guid[3];
+	uuid[1] = guid[2];
+	uuid[2] = guid[1];
+	uuid[3] = guid[0];
+	uuid[4] = guid[5];
+	uuid[5] = guid[4];
+	uuid[6] = guid[7];
+	uuid[7] = guid[6];
+	memcpy(uuid + 8, guid + 8, UUID_SIZE - 8);
+}
+
+static int acpi_ffh_ffa_receiver_id(struct acpi_ffh_data *ffh_ctxt,
+				    u64 uuid_lo, u64 uuid_hi, u16 *receiver_id)
+{
+	struct arm_smccc_1_2_regs args = {
+		.a0 = FFA_PARTITION_INFO_GET_REGS,
+		.a1 = uuid_lo,
+		.a2 = uuid_hi,
+	};
+	struct arm_smccc_1_2_regs res;
+	u32 properties;
+
+	acpi_ffh_ffa_invoke(ffh_ctxt, &args, &res);
+	if (res.a0 != FFA_FN64_SUCCESS)
+		return -EINVAL;
+
+	if (FIELD_GET(FFA_PART_INFO_LAST_IDX_MASK, res.a2) ||
+	    FIELD_GET(FFA_PART_INFO_CUR_IDX_MASK, res.a2) ||
+	    FIELD_GET(FFA_PART_INFO_DESC_SIZE_MASK, res.a2) <
+		    FFA_PART_INFO_MIN_DESC_SIZE)
+		return -EINVAL;
+
+	properties = FIELD_GET(FFA_PART_INFO_PROPS_MASK, res.a3);
+	if (!(properties & FFA_PARTITION_DIRECT_REQ2_RECV))
+		return -EINVAL;
+
+	*receiver_id = FIELD_GET(FFA_PART_INFO_ID_MASK, res.a3);
+	return 0;
+}
+
+static int acpi_ffh_ffa_status(int error)
+{
+	switch (error) {
+	case -EOPNOTSUPP:
+		return FFH_FFA_NOT_SUPPORTED;
+	case -EINVAL:
+		return FFH_FFA_INVALID_PARAMETERS;
+	case -ENOMEM:
+		return FFH_FFA_OUT_OF_MEMORY;
+	default:
+		return FFH_FFA_UNSPECIFIED_ERROR;
+	}
+}
+
+static int acpi_ffh_ffa_direct_req2(acpi_integer *value,
+				    struct acpi_ffh_data *ffh_ctxt)
+{
+	struct arm_smccc_1_2_regs args = { }, res;
+	u64 *buf = (u64 *)value;
+	u64 uuid_lo, uuid_hi;
+	u16 receiver_id = (u16)buf[1];
+	uuid_t uuid;
+	size_t len = ffh_ctxt->info.length;
+	int ret;
+
+	if (len < FFH_FFA_MIN_LEN || len > FFH_FFA_MAX_LEN ||
+	    !IS_ALIGNED(len - 4 * sizeof(u64), sizeof(u64))) {
+		buf[0] = FFH_FFA_INVALID_PARAMETERS;
+		return AE_OK;
+	}
+
+	acpi_ffh_ffa_uuid_convert((u8 *)value + FFH_FFA_UUID_OFFSET, uuid.b);
+	if (uuid_is_null(&uuid)) {
+		buf[0] = FFH_FFA_INVALID_PARAMETERS;
+		return AE_OK;
+	}
+
+	ret = acpi_ffh_ffa_init(ffh_ctxt);
+	if (ret) {
+		buf[0] = acpi_ffh_ffa_status(ret);
+		return AE_OK;
+	}
+
+	uuid_lo = get_unaligned_le64(uuid.b);
+	uuid_hi = get_unaligned_le64(uuid.b + sizeof(uuid_lo));
+	if (!receiver_id) {
+		ret = acpi_ffh_ffa_receiver_id(ffh_ctxt, uuid_lo, uuid_hi,
+					       &receiver_id);
+		if (ret) {
+			buf[0] = FFH_FFA_INVALID_PARAMETERS;
+			return AE_OK;
+		}
+	}
+
+	args.a0 = FFA_MSG_SEND_DIRECT_REQ2;
+	args.a1 = ffa_pack_target_info(acpi_ffh_ffa_sender_id, receiver_id);
+	args.a2 = uuid_lo;
+	args.a3 = uuid_hi;
+	memcpy(&args.a4, &buf[4], len - 4 * sizeof(u64));
+
+	acpi_ffh_ffa_invoke(ffh_ctxt, &args, &res);
+	while (res.a0 == FFA_INTERRUPT || res.a0 == FFA_YIELD) {
+		if (res.a0 == FFA_YIELD)
+			fsleep(1000);
+
+		args = (struct arm_smccc_1_2_regs) {
+			.a0 = FFA_RUN,
+			.a1 = res.a1,
+		};
+		acpi_ffh_ffa_invoke(ffh_ctxt, &args, &res);
+	}
+
+	memcpy(buf, &res, len);
+	if (res.a0 == FFA_MSG_SEND_DIRECT_RESP2 || res.a0 == FFA_SUCCESS ||
+	    res.a0 == FFA_FN64_SUCCESS)
+		buf[0] = FFH_FFA_SUCCESS;
+	else
+		buf[0] = FFH_FFA_CALL_FAILED;
+
+	return AE_OK;
+}
+
 int acpi_ffh_address_space_arch_setup(void *handler_ctxt, void **region_ctxt)
 {
 	enum arm_smccc_conduit conduit;
@@ -99,6 +324,8 @@ int acpi_ffh_address_space_arch_handler(acpi_integer *value, void *region_contex
 			ffh_ctxt->invoke_ffh64_fn(r, r);
 			memcpy(value, r, ffh_ctxt->info.length);
 		}
+	} else if (ffh_ctxt->info.offset == 2) {
+		ret = acpi_ffh_ffa_direct_req2(value, ffh_ctxt);
 	} else {
 		ret = AE_ERROR;
 	}
-- 
2.43.0

Re: [PATCH 2/2] ACPI: FFH: Support FF-A direct request 2 calls

[Jamie Nguyen]

On Tue, Nov 03, 2026 at 05:39:07PM +0000, Sudeep Holla wrote:
[...]
> +	if (!acpi_ffh_ffa_version_negotiated) {
> +		args.a0 = FFA_VERSION;
> +		args.a1 = FFA_VERSION_1_2;

Same question as on the earlier thread: how does this work if the
transport driver has already negotiated a version?

[...]
> +	ret = acpi_ffh_ffa_features(ffh_ctxt, FFA_PARTITION_INFO_GET_REGS);
> +	if (ret)
> +		goto out;

I think REGS is only needed when X1 is zero, and if I understand
correctly it's optional at the Non-secure physical instance. Would it
make sense to check it in the lookup path instead, so an explicit
receiver ID still works without it?

[...]
> +	memcpy(&args.a4, &buf[4], len - 4 * sizeof(u64));

I believe this would trip FORTIFY_SOURCE's field-spanning write check.
So I suggest:

	memcpy((void *)&args + offsetof(struct arm_smccc_1_2_regs, a4),
	       &buf[4], len - 4 * sizeof(u64));

Re: [PATCH 2/2] ACPI: FFH: Support FF-A direct request 2 calls

[Jonathan Cameron]

On Tue,  3 Nov 2026 17:39:07 +0000
Sudeep Holla <sudeep.holla@kernel.org> wrote:

> Arm Functional Fixed Hardware specification v1.3 defines FFH
> OperationRegion offset 2 for issuing FFA_MSG_SEND_DIRECT_REQ2 calls.
> The arm64 FFH handler currently supports only generic 32-bit and 64-bit
> SMCCC calls, so it cannot implement this standardized interface.
> 
> Add a standalone FF-A path using the existing SMCCC conduit. Negotiate
> FF-A v1.2, discover the sender endpoint with FFA_ID_GET, and use either
> the receiver supplied by firmware or resolve a unique receiver from the
> service UUID with FFA_PARTITION_INFO_GET_REGS.
> 
> Convert the ACPI ToUUID representation to the FF-A register encoding,
> construct the direct request, resume interrupted or yielded calls with
> FFA_RUN, and return the defined FFH status codes to AML.
> 
> Register-based partition discovery avoids RX/TX buffer ownership and
> keeps the FFH implementation independent of the Arm FF-A transport
> driver.
> 
> Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>
Hi Sudeep,

I was curious so took a quick look. Some drive by comments inline.

thanks,

Jonathan

> +static int acpi_ffh_ffa_features(struct acpi_ffh_data *ffh_ctxt, u32 fid)
> +{
> +	struct arm_smccc_1_2_regs args = {
> +		.a0 = FFA_FEATURES,
> +		.a1 = fid,
> +	};
> +	struct arm_smccc_1_2_regs res;
> +
> +	acpi_ffh_ffa_invoke(ffh_ctxt, &args, &res);
> +	if (res.a0 == FFA_ERROR) {
> +		if ((s32)res.a2 == FFA_RET_NOT_SUPPORTED)
> +			return -EOPNOTSUPP;
> +		return -EINVAL;
> +	}
> +
> +	return res.a0 == FFA_SUCCESS ? 0 : -EIO;
> +}
> +
> +static int acpi_ffh_ffa_init(struct acpi_ffh_data *ffh_ctxt)
> +{
> +	struct arm_smccc_1_2_regs args = { }, res;
> +	u32 version;
> +	int ret = 0;
> +
> +	mutex_lock(&acpi_ffh_ffa_lock);

Use a guard() here given it will allow direct returns
in all the error paths. Seems like a nice easy code
flow simplification particularly as the good vs bad
paths will be more obvious.


> +	if (acpi_ffh_ffa_initialized)
> +		goto out;

With guard this becomes
		return 0;
and is obviously a good path.

> +
> +	if (!acpi_ffh_ffa_version_negotiated) {
Maybe combine this flag and acpi_ffh_ffa_initialized into
states in a state machine rather than separate bool.

Passing this one just becomes moving to the partly configured
state.

> +		args.a0 = FFA_VERSION;
> +		args.a1 = FFA_VERSION_1_2;

I'd do similar to have below and initialize the whole thing here.
That way no need to look back to see if the rest is correctly
zeroed.

> +		acpi_ffh_ffa_invoke(ffh_ctxt, &args, &res);
> +		version = res.a0;
> +		if ((s32)version == SMCCC_RET_NOT_SUPPORTED ||
> +		    FFA_MAJOR_VERSION(version) != 1 ||
> +		    version < FFA_VERSION_1_2) {
> +			ret = -EOPNOTSUPP;
> +			goto out;
> +		}
> +		acpi_ffh_ffa_version_negotiated = true;
> +	}
> +
> +	ret = acpi_ffh_ffa_features(ffh_ctxt, FFA_MSG_SEND_DIRECT_REQ2);
> +	if (ret)
> +		goto out;
> +
> +	ret = acpi_ffh_ffa_features(ffh_ctxt, FFA_MSG_SEND_DIRECT_RESP2);
> +	if (ret)
> +		goto out;
> +
> +	ret = acpi_ffh_ffa_features(ffh_ctxt, FFA_PARTITION_INFO_GET_REGS);
> +	if (ret)
> +		goto out;
> +
> +	args = (struct arm_smccc_1_2_regs) { .a0 = FFA_ID_GET };
> +	acpi_ffh_ffa_invoke(ffh_ctxt, &args, &res);
> +	if (res.a0 == FFA_ERROR) {
> +		ret = (s32)res.a2 == FFA_RET_NOT_SUPPORTED ?
> +		      -EOPNOTSUPP : -EIO;
> +		goto out;
> +	}
> +	if (res.a0 != FFA_SUCCESS) {
> +		ret = -EIO;
> +		goto out;
> +	}
> +
> +	acpi_ffh_ffa_sender_id = (u16)res.a2;
> +	acpi_ffh_ffa_initialized = true;
> +out:
> +	mutex_unlock(&acpi_ffh_ffa_lock);
> +	return ret;
> +}

Re: [PATCH 2/2] ACPI: FFH: Support FF-A direct request 2 calls

[Sudeep Holla]

On Tue, Nov 03, 2026 at 01:11:36PM -0800, Jamie Nguyen wrote:
> On Tue, Nov 03, 2026 at 05:39:07PM +0000, Sudeep Holla wrote:
> [...]
> > +	if (!acpi_ffh_ffa_version_negotiated) {
> > +		args.a0 = FFA_VERSION;
> > +		args.a1 = FFA_VERSION_1_2;
> 
> Same question as on the earlier thread: how does this work if the
> transport driver has already negotiated a version?
> 

Handling this coordination is difficult, which prompted my earlier query about
requiring v1.3 as a baseline. On ACPI platforms, this initialization conflict
is already an inherent issue, as the UEFI or early bootloader might negotiate
a version before the kernel FF-A driver probes. I welcome any feedback or
proposals on how we might cleanly resolve or track this pre-negotiated state.

> [...]
> > +	ret = acpi_ffh_ffa_features(ffh_ctxt, FFA_PARTITION_INFO_GET_REGS);
> > +	if (ret)
> > +		goto out;
> 
> I think REGS is only needed when X1 is zero, and if I understand
> correctly it's optional at the Non-secure physical instance. Would it
> make sense to check it in the lookup path instead, so an explicit
> receiver ID still works without it?
> 

That is good point. I completely forgot why I didn't add this check in
the RFC patch. Thank you for catching it; I will make sure to include
the proper fallback implementation in the next revision.

> [...]
> > +	memcpy(&args.a4, &buf[4], len - 4 * sizeof(u64));
> 
> I believe this would trip FORTIFY_SOURCE's field-spanning write check.
> So I suggest:
> 
> 	memcpy((void *)&args + offsetof(struct arm_smccc_1_2_regs, a4),
> 	       &buf[4], len - 4 * sizeof(u64));


Apologies for the oversight, as I remember you pointing this out before. I was
rushing to get these patches sent out, but I will make sure it is corrected in
the next revision.

-- 
Regards,
Sudeep

Re: [PATCH 2/2] ACPI: FFH: Support FF-A direct request 2 calls

[Sudeep Holla]

On Tue, Nov 03, 2026 at 02:53:35PM -0800, Jonathan Cameron wrote:
> On Tue,  3 Nov 2026 17:39:07 +0000
> Sudeep Holla <sudeep.holla@kernel.org> wrote:
> 
> > Arm Functional Fixed Hardware specification v1.3 defines FFH
> > OperationRegion offset 2 for issuing FFA_MSG_SEND_DIRECT_REQ2 calls.
> > The arm64 FFH handler currently supports only generic 32-bit and 64-bit
> > SMCCC calls, so it cannot implement this standardized interface.
> > 
> > Add a standalone FF-A path using the existing SMCCC conduit. Negotiate
> > FF-A v1.2, discover the sender endpoint with FFA_ID_GET, and use either
> > the receiver supplied by firmware or resolve a unique receiver from the
> > service UUID with FFA_PARTITION_INFO_GET_REGS.
> > 
> > Convert the ACPI ToUUID representation to the FF-A register encoding,
> > construct the direct request, resume interrupted or yielded calls with
> > FFA_RUN, and return the defined FFH status codes to AML.
> > 
> > Register-based partition discovery avoids RX/TX buffer ownership and
> > keeps the FFH implementation independent of the Arm FF-A transport
> > driver.
> > 
> > Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>
> Hi Sudeep,
> 
> I was curious so took a quick look. Some drive by comments inline.
> 

All good point, will be updated accordingly in the next version. Thanks
for the review.

-- 
Regards,
Sudeep

Re: [PATCH 2/2] ACPI: FFH: Support FF-A direct request 2 calls

[Jamie Nguyen]

On Wed, Nov 04, 2026 at 09:40:08AM +0000, Sudeep Holla wrote:
> Handling this coordination is difficult, which prompted my earlier query about
> requiring v1.3 as a baseline. On ACPI platforms, this initialization conflict
> is already an inherent issue, as the UEFI or early bootloader might negotiate
> a version before the kernel FF-A driver probes. I welcome any feedback or
> proposals on how we might cleanly resolve or track this pre-negotiated state.

From the kernel side: the transport driver and ffh.c are the same FF-A
caller from firmware's point of view. Could a small built-in helper call
FFA_VERSION once, under a mutex, and keep the effective negotiated
version? Both would use it, with the transport's existing compatibility
handling, so it wouldn't matter which runs first.

I haven't been able to think of a clean solution for the bootloader
case, though. It looks like the same hole the transport already has
today, since the helper would negotiate the way ffa_version_check() does
now.