[PATCH v8 09/28] mailbox: Add Gunyah message queue mailbox
Elliot Berman
quic_eberman at quicinc.com
Tue Jan 10 10:16:50 PST 2023
On 1/9/2023 1:34 PM, Alex Elder wrote:
> On 12/19/22 4:58 PM, Elliot Berman wrote:
>> Gunyah message queues are a unidirectional inter-VM pipe for messages up
>
> s/Gunyah message queues are/A Gunyah message queue is/
>
>> to 1024 bytes. This driver supports pairing a receiver message queue and
>> a transmitter message queue to expose a single mailbox channel.
>>
>> Signed-off-by: Elliot Berman <quic_eberman at quicinc.com>
>> ---
>> Documentation/virt/gunyah/message-queue.rst | 8 +
>> MAINTAINERS | 1 +
>> drivers/mailbox/Kconfig | 10 +
>> drivers/mailbox/Makefile | 2 +
>> drivers/mailbox/gunyah-msgq.c | 229 ++++++++++++++++++++
>> include/linux/gunyah.h | 61 +++++-
>> 6 files changed, 309 insertions(+), 2 deletions(-)
>> create mode 100644 drivers/mailbox/gunyah-msgq.c
>>
>> diff --git a/Documentation/virt/gunyah/message-queue.rst
>> b/Documentation/virt/gunyah/message-queue.rst
>> index be4ab289236a..9245dbe6dd8a 100644
>> --- a/Documentation/virt/gunyah/message-queue.rst
>> +++ b/Documentation/virt/gunyah/message-queue.rst
>> @@ -54,3 +54,11 @@ vIRQ: two TX message queues will have two vIRQs
>> (and two capability IDs).
>> | | | |
>> | |
>> | | | |
>> | |
>> +---------------+ +-----------------+
>> +---------------+
>> +
>> +Gunyah message queues are exposed as mailboxes. To create the
>> mailbox, create
>> +a mbox_client and call `gh_msgq_init`. On receipt of the RX_READY
>> interrupt,
>> +all messages in the RX message queue are read and pushed via the
>> `rx_callback`
>> +of the registered mbox_client.
>> +
>> +.. kernel-doc:: drivers/mailbox/gunyah-msgq.c
>> + :identifiers: gh_msgq_init
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 36698df6b0e5..667480bfd387 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -8942,6 +8942,7 @@ S: Supported
>> F: Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
>> F: Documentation/virt/gunyah/
>> F: arch/arm64/gunyah/
>> +F: drivers/mailbox/gunyah-msgq.c
>> F: drivers/virt/gunyah/
>> F: include/linux/gunyah.h
>> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
>> index 05d6fae800e3..baf9451c5f04 100644
>> --- a/drivers/mailbox/Kconfig
>> +++ b/drivers/mailbox/Kconfig
>> @@ -41,6 +41,16 @@ config IMX_MBOX
>> help
>> Mailbox implementation for i.MX Messaging Unit (MU).
>> +config GUNYAH_MESSAGE_QUEUES
>
> Is Gunyah useful without message queues? Are Gunyah message
> queues useful without the rest of Gunyah? Are there other
> possible message queue implementations? My point is that
> maybe this isn't a necessary kernel config option.
>
I can drop this.
>> + tristate "Gunyah Message Queue Mailbox"
>> + depends on GUNYAH
>> + help
>> + Mailbox implementation for Gunyah Message Queues. Gunyah
>> message queues
>> + are an IPC mechanism to pass short messages between virtual
>> machines
>> + running under the Gunyah hypervisor.
>> +
>> + Say Y here if you run Linux as a Gunyah virtual machine.
>> +
>> config PLATFORM_MHU
>> tristate "Platform MHU Mailbox"
>> depends on OF
>> diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
>> index fc9376117111..5f929bb55e9a 100644
>> --- a/drivers/mailbox/Makefile
>> +++ b/drivers/mailbox/Makefile
>> @@ -55,6 +55,8 @@ obj-$(CONFIG_MTK_CMDQ_MBOX) += mtk-cmdq-mailbox.o
>> obj-$(CONFIG_ZYNQMP_IPI_MBOX) += zynqmp-ipi-mailbox.o
>> +obj-$(CONFIG_GUNYAH) += gunyah-msgq.o
>
> Assuming you keep the Kconfig option, should this be
> referring to CONFIG_GUNYAH_MESSAGE_QUEUES?
>
>> +
>> obj-$(CONFIG_SUN6I_MSGBOX) += sun6i-msgbox.o
>> obj-$(CONFIG_SPRD_MBOX) += sprd-mailbox.o
>> diff --git a/drivers/mailbox/gunyah-msgq.c
>> b/drivers/mailbox/gunyah-msgq.c
>> new file mode 100644
>> index 000000000000..d5a324e85428
>> --- /dev/null
>> +++ b/drivers/mailbox/gunyah-msgq.c
>> @@ -0,0 +1,229 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights
>> reserved.
>> + */
>> +
>> +#include <linux/mailbox_controller.h>
>> +#include <linux/module.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/gunyah.h>
>> +#include <linux/printk.h>
>> +#include <linux/init.h>
>> +#include <linux/slab.h>
>> +#include <linux/wait.h>
>> +
>> +#define mbox_chan_to_msgq(chan) (container_of(chan->mbox, struct
>> gh_msgq, mbox))
>> +
>> +static inline bool gh_msgq_has_tx(struct gh_msgq *msgq)
>> +{
>> + return msgq->tx_ghrsc->type == GUNYAH_RESOURCE_TYPE_MSGQ_TX;
>
> I think this was pointed out elsewhere; I think msgq->tx_ghrsc
> can be null. Same for msgq->rx_ghrsc below.
>
>> +}
>> +
>> +static inline bool gh_msgq_has_rx(struct gh_msgq *msgq)
>> +{
>> + return msgq->rx_ghrsc->type == GUNYAH_RESOURCE_TYPE_MSGQ_RX;
>
> Is there any chance that a message queue would be created whose
> type was anything other than MSGQ_RX? It's possible that there
> is some generic resource code that needs this type field, but
> in this case I don't see why it's important.
>
> And... If that's the case, I think it's perhaps clearer to
> just replace calls to gs_msgq_has_rx(msgq) with:
>
> if (msgq->rx_ghrsc)
> /* there is an RX message queue */
>
Yep, that's what I've done for v9.
>> +}
>> +
>> +static irqreturn_t gh_msgq_rx_irq_handler(int irq, void *data)
>> +{
>> + struct gh_msgq *msgq = data;
>> + struct gh_msgq_rx_data rx_data;
>> + unsigned long gh_err;
>> + ssize_t ret;
>> + bool ready = false;
>> +
>> + do {
>
> Maybe: bool ready = true;
>
> while (ready) {
>> + gh_err = gh_hypercall_msgq_recv(msgq->rx_ghrsc->capid,
>> + (uintptr_t)&rx_data.data, sizeof(rx_data.data),
>> + &rx_data.length, &ready);
>> + if (gh_err == GH_ERROR_OK) {
>> + mbox_chan_received_data(gh_msgq_chan(msgq), &rx_data);
>
> Maybe continue;
> }
>
> if (gh_err != GH_ERROR_MSGQUEUE_EMPTY)
> pr_warn(...);
>
> break;
>
>> + } else if (GH_ERROR_MSGQUEUE_EMPTY) {
>> + break;
>> + } else {
>> + pr_warn("Failed to receive data from msgq for %s: %ld\n",
>
> s/%ld/%zd/
>
>> + msgq->mbox.dev ? dev_name(msgq->mbox.dev) : "", ret);
>> + break;
>> + }
>> + } while (ready);
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static irqreturn_t gh_msgq_tx_irq_handler(int irq, void *data)
>> +{
>> + struct gh_msgq *msgq = data;
>> +
>> + mbox_chan_txdone(gh_msgq_chan(msgq), 0);
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static void gh_msgq_txdone_tasklet(struct tasklet_struct *tasklet)
>> +{
>> + struct gh_msgq *msgq = container_of(tasklet, struct gh_msgq,
>> txdone_tasklet);
>> +
>> + mbox_chan_txdone(gh_msgq_chan(msgq), msgq->last_status);
>> +}
>> +
>> +static int gh_msgq_send_data(struct mbox_chan *chan, void *data)
>> +{
>> + struct gh_msgq *msgq = mbox_chan_to_msgq(chan);
>> + struct gh_msgq_tx_data *msgq_data = data;
>> + u64 tx_flags = 0;
>> + unsigned long ret;
>> + bool ready;
>> +
>> + if (msgq_data->push)
>> + tx_flags |= GH_HYPERCALL_MSGQ_TX_FLAGS_PUSH;
>> +
>
> I probably missed something, but where is gh_hypercall_msgq_send()
> defined? I'm interested in what the ready flag is used for.
> (Can the return value encode that?)
>
It's in arch/arm64/gunyah/gunyah_hypercall.c. The return values of
encode whether more data can be received (ready flag).
>> + ret = gh_hypercall_msgq_send(msgq->tx_ghrsc->capid,
>> msgq_data->length,
>> + (uintptr_t)msgq_data->data, tx_flags, &ready);
>> +
>> + /**
>> + * unlikely because Linux tracks state of msgq and should not try to
>> + * send message when msgq is full.
>> + */
>
> Is it just unlikely, or is it impossible?
>
This would require multiple mailbox controllers interacting with the
same message queue.
The only way I can think this is possible is if the Gunyah drivers are
unloaded when the message queue is full; drivers are then re-loaded
before the receiver processes the messages. The initial internal state
of the message queue controller assumes that there is space in the
message queue. We would get a Tx vIRQ once space becomes available and
the message would then be attempted to sent again. Since there's a safe
flow to recover from a inconsistent internal state and it's very
unlikely to start in that state, I don't think we need to add calls to
check if the message queue is full during initialization.
>> + if (unlikely(ret == GH_ERROR_MSGQUEUE_FULL))
>> + return -EAGAIN;
>> +
>> + /**
>> + * Propagate all other errors to client. If we return error to
>> mailbox
>> + * framework, then no other messages can be sent and nobody will
>> know
>> + * to retry this message.
>> + */
>> + msgq->last_status = gh_remap_error(ret);
>> +
>> + /**
>> + * This message was successfully sent, but message queue isn't
>> ready to
>> + * receive more messages because it's now full.Mailbox framework
>> + * requires that we only report that message was transmitted only
>> when
>
> s/only // (for one of them)
>
>> + * we're ready to transmit another message. We'll get that in the
>> form
>> + * of tx IRQ once the other side starts to drain the msgq.
>> + */
>> + if (ret == GH_ERROR_OK && !ready)
>> + return 0;
>> +
>> + /**
>> + * We can send more messages. Mailbox frameworkrequires that tx
>> done
>> + * happens asynchronously to sending the message. Gunyah message
>> queues
>> + * tell us right away on the hypercall return whether we can send
>> more
>> + * messages. To work around this, defer the txdone to a tasklet.
>> + */
>> + tasklet_schedule(&msgq->txdone_tasklet);
>> +
>> + return 0;
>> +}
>> +
>> +struct mbox_chan_ops gh_msgq_ops = {
>> + .send_data = gh_msgq_send_data,
>> +};
>> +
>> +/**
>> + * gh_msgq_init() - Initialize a Gunyah message queue with an
>> mbox_client
>> + * @parent: optional, device parent used for the mailbox controller
>> + * @msgq: Pointer to the gh_msgq to initialize
>> + * @cl: A mailbox client to bind to the mailbox channel that the
>> message queue creates
>> + * @tx_ghrsc: optional, the transmission side of the message queue
>> + * @rx_ghrsc: optional, the receiving side of the message queue
>> + *
>> + * At least one of tx_ghrsc and rx_ghrsc should be not NULL. Most
>> message queue use cases come with
>> + * a pair of message queues to facilitiate bidirectional
>> communication. When tx_ghrsc is set,
>
> s/facilitiate/facilitate/
>
>> + * the client can send messages with
>> mbox_send_message(gh_msgq_chan(msgq), msg). When rx_ghrsc
>> + * is set, the mbox_client should register an .rx_callback() and the
>> message queue driver will
>> + * push all available messages upon receiving the RX ready interrupt.
>> The messages should be
>> + * consumed or copied by the client right away as the gh_msgq_rx_data
>> will be replaced/destroyed
>> + * after the callback.
>> + *
>> + * Returns - 0 on success, negative otherwise
>> + */
>> +int gh_msgq_init(struct device *parent, struct gh_msgq *msgq, struct
>> mbox_client *cl,
>> + struct gunyah_resource *tx_ghrsc, struct gunyah_resource
>> *rx_ghrsc)
>> +{
>> + int ret;
>> +
>> + /* Must have at least a tx_ghrsc or rx_ghrsc and that they are
>> the right device types */
>> + if ((!tx_ghrsc && !rx_ghrsc) ||
>> + (tx_ghrsc && tx_ghrsc->type != GUNYAH_RESOURCE_TYPE_MSGQ_TX) ||
>> + (rx_ghrsc && rx_ghrsc->type != GUNYAH_RESOURCE_TYPE_MSGQ_RX))
>
> The internal parenthesis pairs above aren't really required.
>
>
I think it's cleaner/easier to read this way.
>> + return -EINVAL;
>> +
>> + msgq->tx_ghrsc = tx_ghrsc;
>> + msgq->rx_ghrsc = rx_ghrsc;
>> +
>> + msgq->mbox.dev = parent;
>> + msgq->mbox.ops = &gh_msgq_ops;
>> + msgq->mbox.num_chans = 1;
>> + msgq->mbox.chans = kcalloc(msgq->mbox.num_chans,
>> sizeof(*msgq->mbox.chans), GFP_KERNEL);
>> + if (!msgq->mbox.chans)
>> + return -ENOMEM;
>> + msgq->mbox.txdone_irq = true;
>> +
>> + if (gh_msgq_has_tx(msgq)) {
>
> Maybe if (tx_ghrsc) {
>
>> + ret = request_irq(msgq->tx_ghrsc->irq,
>> gh_msgq_tx_irq_handler, 0, "gh_msgq_tx",
>> + msgq);
>> + if (ret)
>> + gotoerr_chans;
>> + }
>> +
>> + if (gh_msgq_has_rx(msgq)) {
>
> Maybe if (rx_ghrsc) {
>
>> + ret = request_threaded_irq(msgq->rx_ghrsc->irq, NULL,
>> gh_msgq_rx_irq_handler,
>> + IRQF_ONESHOT, "gh_msgq_rx", msgq);
>> + if (ret)
>> + gotoerr_tx_irq;
>> + }
>> +
>> + tasklet_setup(&msgq->txdone_tasklet, gh_msgq_txdone_tasklet);
>> +
>> + ret = mbox_controller_register(&msgq->mbox);
>> + if (ret)
>> + goto err_rx_irq;
>> +
>> + ret = mbox_bind_client(gh_msgq_chan(msgq), cl);
>> + if (ret)
>> + goto err_mbox;
>> +
>> + return 0;
>> +err_mbox:
>> + mbox_controller_unregister(&msgq->mbox);
>> +err_rx_irq:
>> + if (gh_msgq_has_rx(msgq))
>
> if (rx_ghrsc)
>
>> + free_irq(msgq->rx_ghrsc->irq, msgq);
>> +err_tx_irq:
>> + if (gh_msgq_has_tx(msgq))
>
> if (tx_ghrsc)
>
Applied for the suggestions above.
>> + free_irq(msgq->tx_ghrsc->irq, msgq);
>> +err_chans:
>> + kfree(msgq->mbox.chans);
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(gh_msgq_init);
>> +
>> +void gh_msgq_remove(struct gh_msgq *msgq)
>> +{
>> + mbox_controller_unregister(&msgq->mbox);
>> +
>> + if (gh_msgq_has_rx(msgq))
>> + free_irq(msgq->rx_ghrsc->irq, msgq);
>> +
>> + if (gh_msgq_has_tx(msgq))
>> + free_irq(msgq->tx_ghrsc->irq, msgq);
>> +
>> + kfree(msgq->mbox.chans);
>> +}
>> +EXPORT_SYMBOL_GPL(gh_msgq_remove);
>> +
>> +
>> +static int __init gh_msgq_init_module(void)
>> +{
>> + if (gh_api_version() != GUNYAH_API_V1) {
>> + pr_warn("Unrecognized gunyahversion: %u. Currently
>> supported: %d\n",
>> + gh_api_version(), GUNYAH_API_V1);
>> + return -ENODEV;
>> + }
>> +
>> + return 0;
>> +}
>> +module_init(gh_msgq_init_module);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_DESCRIPTION("Gunyah Message Queue Driver");
>> diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
>> index c863cac4a3cf..e317d7ac938f 100644
>> --- a/include/linux/gunyah.h
>> +++ b/include/linux/gunyah.h
>> @@ -7,10 +7,67 @@
>> #define _GUNYAH_H
>> #include <linux/bitfield.h>
>> -#include <linux/types.h>
>> #include <linux/errno.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/mailbox_controller.h>
>> +#include <linux/mailbox_client.h>
>> +#include <linux/types.h>
>> +
>> +/* Follows resource manager's resource types for VM_GET_HYP_RESOURCES */
>> +enum gunyah_resource_type {
>> + GUNYAH_RESOURCE_TYPE_BELL_TX = 0,
>> + GUNYAH_RESOURCE_TYPE_BELL_RX = 1,
>> + GUNYAH_RESOURCE_TYPE_MSGQ_TX = 2,
>> + GUNYAH_RESOURCE_TYPE_MSGQ_RX = 3,
>> + GUNYAH_RESOURCE_TYPE_VCPU = 4,
>> +};
>> +
>> +struct gunyah_resource {
>> + enum gunyah_resource_type type;
>> + u64 capid;
>> + int irq;
>> +};
>> +
>> +/**
>> + * Gunyah Message Queues
>> + */
>> +
>> +#define GH_MSGQ_MAX_MSG_SIZE 240
>> +
>> +struct gh_msgq_tx_data {
>> + size_t length;
>> + bool push;
>> + char data[];
>> +};
>> +
>> +struct gh_msgq_rx_data {
>> + size_t length;
>> + char data[GH_MSGQ_MAX_MSG_SIZE];
>> +};
>> +
>> +struct gh_msgq {
>> + struct gunyah_resource *tx_ghrsc;
>> + struct gunyah_resource *rx_ghrsc;
>> +
>> + /* msgq private */
>> + int last_status;
>
> Maybe note that last_status is an errno (and not GH_ERROR_*)
>
Done, renamed to "last_ret".
> -Alex
>
>> + struct mbox_controller mbox;
>> + struct tasklet_struct txdone_tasklet;
>> +};
>> +
>> +
>> +int gh_msgq_init(struct device *parent, struct gh_msgq *msgq, struct
>> mbox_client *cl,
>> + struct gunyah_resource *tx_ghrsc, struct gunyah_resource
>> *rx_ghrsc);
>> +void gh_msgq_remove(struct gh_msgq *msgq);
>> +
>> +static inline struct mbox_chan *gh_msgq_chan(struct gh_msgq *msgq)
>> +{
>> + return &msgq->mbox.chans[0];
>> +}
>> +
>> +/******************************************************************************/
>> +/* Common arch-independent macros and definitions for Gunyah
>> hypercalls */
>> -/* Common Gunyah macros */
>> #define GH_CAPID_INVAL U64_MAX
>> #define GH_VMID_ROOT_VM 0xff
>
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