On 3/3/23 7:06 PM, Elliot Berman wrote:

The resource manager is a special virtual machine which is always
running on a Gunyah system. It provides APIs for creating and destroying
VMs, secure memory management, sharing/lending of memory between VMs,
and setup of inter-VM communication. Calls to the resource manager are
made via message queues.

This patch implements the basic probing and RPC mechanism to make those
API calls. Request/response calls can be made with gh_rm_call.
Drivers can also register to notifications pushed by RM via
gh_rm_register_notifier

Specific API calls that resource manager supports will be implemented in
subsequent patches.

Mostly very simple issues noted here.	-Alex

. . .

+static void gh_rm_try_complete_connection(struct gh_rm *rm)
+{
+	struct gh_rm_connection *connection = rm->active_rx_connection;
+
+	if (!connection || connection->fragments_received != connection->num_fragments)
+		return;
+
+	switch (connection->type) {
+	case RM_RPC_TYPE_REPLY:
+		complete(&connection->reply.seq_done);
+		break;
+	case RM_RPC_TYPE_NOTIF:
+		schedule_work(&connection->notification.work);
+		break;
+	default:
+		dev_err_ratelimited(rm->dev, "Invalid message type (%d) received\n",

s/%d/%u/

+					connection->type);
+		gh_rm_abort_connection(rm);
+		break;
+	}
+
+	rm->active_rx_connection = NULL;
+}
+
+static void gh_rm_msgq_rx_data(struct mbox_client *cl, void *mssg)
+{
+	struct gh_rm *rm = container_of(cl, struct gh_rm, msgq_client);
+	struct gh_msgq_rx_data *rx_data = mssg;
+	size_t msg_size = rx_data->length;
+	void *msg = rx_data->data;
+	struct gh_rm_rpc_hdr *hdr;
+
+	if (msg_size < sizeof(*hdr) || msg_size > GH_MSGQ_MAX_MSG_SIZE)
+		return;
+
+	hdr = msg;
+	if (hdr->api != RM_RPC_API) {
+		dev_err(rm->dev, "Unknown RM RPC API version: %x\n", hdr->api);
+		return;
+	}
+
+	switch (FIELD_GET(RM_RPC_TYPE_MASK, hdr->type)) {
+	case RM_RPC_TYPE_NOTIF:
+		gh_rm_process_notif(rm, msg, msg_size);
+		break;
+	case RM_RPC_TYPE_REPLY:
+		gh_rm_process_rply(rm, msg, msg_size);
+		break;
+	case RM_RPC_TYPE_CONTINUATION:
+		gh_rm_process_cont(rm, rm->active_rx_connection, msg, msg_size);
+		break;
+	default:
+		dev_err(rm->dev, "Invalid message type (%lu) received\n",
+			FIELD_GET(RM_RPC_TYPE_MASK, hdr->type));
+		return;
+	}
+
+	gh_rm_try_complete_connection(rm);
+}
+
+static void gh_rm_msgq_tx_done(struct mbox_client *cl, void *mssg, int r)
+{
+	struct gh_rm *rm = container_of(cl, struct gh_rm, msgq_client);
+
+	kmem_cache_free(rm->cache, mssg);
+	rm->last_tx_ret = r;
+}
+
+static int gh_rm_send_request(struct gh_rm *rm, u32 message_id,
+			      const void *req_buff, size_t req_buf_size,
+			      struct gh_rm_connection *connection)
+{
+	size_t buf_size_remaining = req_buf_size;
+	const void *req_buf_curr = req_buff;
+	struct gh_msgq_tx_data *msg;
+	struct gh_rm_rpc_hdr *hdr, hdr_template;
+	u32 cont_fragments = 0;
+	size_t payload_size;
+	void *payload;
+	int ret;
+
+	if (req_buf_size > GH_RM_MAX_NUM_FRAGMENTS * GH_RM_MAX_MSG_SIZE) {
+		dev_warn(rm->dev, "Limit exceeded for the number of fragments: %u\n",
+			cont_fragments);

You are printing the value of cont_fragments here when it's just zero.

+		dump_stack();
+		return -E2BIG;
+	}
+

Move the computation of cont_fragments prior to the block above.
You could use a ?: statement to assign it.

+	if (req_buf_size)
+		cont_fragments = (req_buf_size - 1) / GH_RM_MAX_MSG_SIZE;
+
+	hdr_template.api = RM_RPC_API;
+	hdr_template.type = FIELD_PREP(RM_RPC_TYPE_MASK, RM_RPC_TYPE_REQUEST) |
+			FIELD_PREP(RM_RPC_FRAGMENTS_MASK, cont_fragments);

The line above should be indented further.

+	hdr_template.seq = cpu_to_le16(connection->reply.seq);
+	hdr_template.msg_id = cpu_to_le32(message_id);
+
+	ret = mutex_lock_interruptible(&rm->send_lock);
+	if (ret)
+		return ret;
+
+	/* Consider also the 'request' packet for the loop count */

I don't think the comment above is helpful.

+	do {
+		msg = kmem_cache_zalloc(rm->cache, GFP_KERNEL);
+		if (!msg) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		/* Fill header */
+		hdr = (struct gh_rm_rpc_hdr *)msg->data;

I personally would prefer &msg->data[0] in this case.

+		*hdr = hdr_template;
+
+		/* Copy payload */
+		payload = hdr + 1;

I think I might have suggested using "hdr + 1" here.

Elsewhere you use something like:
	payload = (char *)hdr + sizeof(hdr);
or something similar.  I suggest you choose one approach and use
it consistently througout the driver.  Either is fine, but I
have a slight preference for the "hdr + 1" way.

+		payload_size = min(buf_size_remaining, GH_RM_MAX_MSG_SIZE);
+		memcpy(payload, req_buf_curr, payload_size);
+		req_buf_curr += payload_size;
+		buf_size_remaining -= payload_size;
+
+		/* Force the last fragment to immediately alert the receiver */
+		msg->push = !buf_size_remaining;
+		msg->length = sizeof(*hdr) + payload_size;
+
+		ret = mbox_send_message(gh_msgq_chan(&rm->msgq), msg);
+		if (ret < 0) {
+			kmem_cache_free(rm->cache, msg);
+			break;
+		}
+
+		if (rm->last_tx_ret) {
+			ret = rm->last_tx_ret;
+			break;
+		}
+
+		hdr_template.type = FIELD_PREP(RM_RPC_TYPE_MASK, RM_RPC_TYPE_CONTINUATION) |
+					FIELD_PREP(RM_RPC_FRAGMENTS_MASK, cont_fragments);
+	} while (buf_size_remaining);
+
+out:
+	mutex_unlock(&rm->send_lock);
+	return ret < 0 ? ret : 0;
+}
+
+/**
+ * gh_rm_call: Achieve request-response type communication with RPC
+ * @rm: Pointer to Gunyah resource manager internal data
+ * @message_id: The RM RPC message-id
+ * @req_buff: Request buffer that contains the payload
+ * @req_buf_size: Total size of the payload
+ * @resp_buf: Pointer to a response buffer
+ * @resp_buf_size: Size of the response buffer
+ *
+ * Make a request to the RM-VM and wait for reply back. For a successful

I think you could just say "to the RM and wait"...

Overall I suggest using "RM" or "RM VM" consistently when you talk
about the Resource Manager.  This is the only place I see "RM-VM".

+ * response, the function returns the payload. The size of the payload is set in
+ * resp_buf_size. The resp_buf should be freed by the caller when 0 is returned

s/should/must/

+ * and resp_buf_size != 0.
+ *
+ * req_buff should be not NULL for req_buf_size >0. If req_buf_size == 0,
+ * req_buff *can* be NULL and no additional payload is sent.

I'd say use "buf" or "buff" but not both in your naming
convention.

+ *
+ * Context: Process context. Will sleep waiting for reply.
+ * Return: 0 on success. <0 if error.
+ */
+int gh_rm_call(struct gh_rm *rm, u32 message_id, void *req_buff, size_t req_buf_size,
+		void **resp_buf, size_t *resp_buf_size)

I suspect you could define the request buffer as a pointer to const;
can you?

+{
+	struct gh_rm_connection *connection;
+	u32 seq_id;
+	int ret;
+
+	/* message_id 0 is reserved. req_buf_size implies req_buf is not NULL */
+	if (!message_id || (!req_buff && req_buf_size) || !rm)

If you're going to check for a null RM pointer, I'd check it first.

+		return -EINVAL;
+
+
+	connection = kzalloc(sizeof(*connection), GFP_KERNEL);
+	if (!connection)
+		return -ENOMEM;
+
+	connection->type = RM_RPC_TYPE_REPLY;
+	connection->msg_id = cpu_to_le32(message_id);
+
+	init_completion(&connection->reply.seq_done);

. . .

Add a tab before U16_MAX; it will line up more nicely
when you define GH_MEM_HANDLE_INVAL later.

+
+struct gh_rm;
+int gh_rm_notifier_register(struct gh_rm *rm, struct notifier_block *nb);
+int gh_rm_notifier_unregister(struct gh_rm *rm, struct notifier_block *nb);
+struct device *gh_rm_get(struct gh_rm *rm);
+void gh_rm_put(struct gh_rm *rm);
+
+#endif

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