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Message-ID: <b4a96d07-d788-93b4-eb23-217dce1fb56e@quicinc.com>
Date: Mon, 3 Apr 2023 13:34:54 -0700
From: Elliot Berman <quic_eberman@...cinc.com>
To: Alex Elder <elder@...aro.org>,
Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
Prakruthi Deepak Heragu <quic_pheragu@...cinc.com>
CC: Murali Nalajala <quic_mnalajal@...cinc.com>,
Trilok Soni <quic_tsoni@...cinc.com>,
Srivatsa Vaddagiri <quic_svaddagi@...cinc.com>,
Carl van Schaik <quic_cvanscha@...cinc.com>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Bjorn Andersson <andersson@...nel.org>,
"Konrad Dybcio" <konrad.dybcio@...aro.org>,
Arnd Bergmann <arnd@...db.de>,
"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Jonathan Corbet <corbet@....net>,
Bagas Sanjaya <bagasdotme@...il.com>,
Will Deacon <will@...nel.org>, Andy Gross <agross@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Jassi Brar <jassisinghbrar@...il.com>,
<linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v11 08/26] gunyah: rsc_mgr: Add resource manager RPC core
On 3/31/2023 7:25 AM, Alex Elder wrote:
> 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@...cinc.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.
>
I think you might be referencing the memcpy in
gh_rm_init_connection_payload. In the gh_rm_init_connection_payload,
hdr_size is not fixed: for notifications, it's just the RPC header. For
responses, there is the RPC header + the "RM error code". To be able to
re-use same header processing, I'd have to do byte arithmetic rather
than the "hdr + 1" way. I also prefer the "hdr + 1" way, but if I am
going to be consistent, need to stick with byte arithmetic.
>> + 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.
>
Not intentional -- will make it consistent.
>> + *
>> + * 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?
>
I can!
>> +{
>> + 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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