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SubjectRe: [PATCH v11 08/26] gunyah: rsc_mgr: Add resource manager RPC core
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

> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> ---
> drivers/virt/gunyah/Makefile | 3 +
> drivers/virt/gunyah/rsc_mgr.c | 688 +++++++++++++++++++++++++++++++++
> drivers/virt/gunyah/rsc_mgr.h | 16 +
> include/linux/gunyah_rsc_mgr.h | 21 +
> 4 files changed, 728 insertions(+)
> create mode 100644 drivers/virt/gunyah/rsc_mgr.c
> create mode 100644 drivers/virt/gunyah/rsc_mgr.h
> create mode 100644 include/linux/gunyah_rsc_mgr.h
>
> diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile
> index 34f32110faf9..cc864ff5abbb 100644
> --- a/drivers/virt/gunyah/Makefile
> +++ b/drivers/virt/gunyah/Makefile
> @@ -1,3 +1,6 @@
> # SPDX-License-Identifier: GPL-2.0
>
> obj-$(CONFIG_GUNYAH) += gunyah.o
> +
> +gunyah_rsc_mgr-y += rsc_mgr.o
> +obj-$(CONFIG_GUNYAH) += gunyah_rsc_mgr.o
> diff --git a/drivers/virt/gunyah/rsc_mgr.c b/drivers/virt/gunyah/rsc_mgr.c
> new file mode 100644
> index 000000000000..67813c9a52db
> --- /dev/null
> +++ b/drivers/virt/gunyah/rsc_mgr.c
> @@ -0,0 +1,688 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +

. . .

> +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);

. . .

> diff --git a/include/linux/gunyah_rsc_mgr.h b/include/linux/gunyah_rsc_mgr.h
> new file mode 100644
> index 000000000000..deca9b3da541
> --- /dev/null
> +++ b/include/linux/gunyah_rsc_mgr.h
> @@ -0,0 +1,21 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#ifndef _GUNYAH_RSC_MGR_H
> +#define _GUNYAH_RSC_MGR_H
> +
> +#include <linux/list.h>
> +#include <linux/notifier.h>
> +#include <linux/gunyah.h>
> +
> +#define GH_VMID_INVAL U16_MAX

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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