Re: [PATCH v9 08/27] mailbox: Add Gunyah message queue mailbox

Srinivas Kandagatla
2023-02-02T09:59:26Z

On 20/01/2023 22:46, Elliot Berman wrote:
> Gunyah message queues are a unidirectional inter-VM pipe for messages up
> 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@quicinc.com>
> ---
> Documentation/virt/gunyah/message-queue.rst | 8 +
> MAINTAINERS | 1 +
> drivers/mailbox/Makefile | 2 +
> drivers/mailbox/gunyah-msgq.c | 214 ++++++++++++++++++++
> include/linux/gunyah.h | 59 +++++-
> 5 files changed, 283 insertions(+), 1 deletion(-)
> 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 0667b3eb1ff9..082085e981e0 100644
> --- a/Documentation/virt/gunyah/message-queue.rst
> +++ b/Documentation/virt/gunyah/message-queue.rst
> @@ -59,3 +59,11 @@ 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 fe19e71efc6d..d02e8abe6457 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9049,6 +9049,7 @@ 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/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-$(CONFIG_GUNYAH) += gunyah-msgq.o
> +
> obj-$(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..caa283f7248b
> --- /dev/null
> +++ b/drivers/mailbox/gunyah-msgq.c
> @@ -0,0 +1,214 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2022-2023 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 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;
> + bool ready = true;
> +
> + while (ready) {
> + gh_err = gh_hypercall_msgq_recv(msgq->rx_ghrsc->capid,
> + (uintptr_t)&rx_data.data, sizeof(rx_data.data),
you should proabably use GH_MSGQ_MAX_MSG_SIZE instead of calling sizeof
for every loop.

> + &rx_data.length, &ready);
> + if (gh_err == GH_ERROR_OK) {
> + mbox_chan_received_data(gh_msgq_chan(msgq), &rx_data);
> + } else if (gh_err == GH_ERROR_MSGQUEUE_EMPTY) {
> + break;
> + } else {
> + pr_warn("Failed to receive data from msgq for %s: %zd\n",
> + msgq->mbox.dev ? dev_name(msgq->mbox.dev) : "", gh_err);
> + break;
> + }
> + }
> +
> + return IRQ_HANDLED;
> +}
How about making this more readable.
also use of gh_ in local variables is not really adding any value.

while (ready) {
err = gh_hypercall_msgq_recv(...);
if (err) {
if (err != GH_ERROR_MSGQUEUE_EMPTY)
dev_warn(msgq->mbox.dev, "Failed to receive data
%zd\n", err);
break;

}
mbox_chan_received_data(gh_msgq_chan(msgq), &rx_data);
}

> +
> +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);
What is this irq for? Is it for tx done ack?

> +
> + 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_ret);
> +}
> +
> +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;
> +
> + 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.
> + */
> + 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_ret = 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 when
> + * 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 framework requires 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;
> +}
> +
> +static 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 facilitate bidirectional communication. When tx_ghrsc is set,
> + * 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))
> + return -EINVAL;
> +
> + if (gh_api_version() != GUNYAH_API_V1) {
> + pr_warn("Unrecognized gunyah version: %u. Currently supported: %d\n",
> + gh_api_version(), GUNYAH_API_V1);
how about using dev_err here?

> + return -ENODEV;

-EOPNOTSUPP?

> + }
> +
> + if (!gh_api_has_feature(GH_API_FEATURE_MSGQUEUE))
> + return -EOPNOTSUPP;
> +
> + 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;

new line here would be nice.
> + msgq->mbox.txdone_irq = true;
> +
> + if (msgq->tx_ghrsc) {
> + ret = request_irq(msgq->tx_ghrsc->irq, gh_msgq_tx_irq_handler, 0, "gh_msgq_tx",
> + msgq);
> + if (ret)
> + goto err_chans;
> + }
> +
> + if (msgq->rx_ghrsc) {
> + ret = request_threaded_irq(msgq->rx_ghrsc->irq, NULL, gh_msgq_rx_irq_handler,
> + IRQF_ONESHOT, "gh_msgq_rx", msgq);
> + if (ret)
> + goto err_tx_irq;
> + }
> +
> + tasklet_setup(&msgq->txdone_tasklet, gh_msgq_txdone_tasklet);

AFAIU, this looks like duplicating what core already has with
TXDONE_BY_POLL.

can we not use
txdone_poll = true
and implement last_tx_done callback to use hrtimer from the core to tick tx.

--srini
> +
> + 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 (msgq->rx_ghrsc)
> + free_irq(msgq->rx_ghrsc->irq, msgq);
> +err_tx_irq:
> + if (msgq->tx_ghrsc)
> + 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 (msgq->rx_ghrsc)
> + free_irq(msgq->rx_ghrsc->irq, msgq);
> +
> + if (msgq->tx_ghrsc)
> + free_irq(msgq->tx_ghrsc->irq, msgq);
> +
> + kfree(msgq->mbox.chans);
> +}
> +EXPORT_SYMBOL_GPL(gh_msgq_remove);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Gunyah Message Queue Driver");
> diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
> index b5f61c14ec1e..5d6fc9f88718 100644
> --- a/include/linux/gunyah.h
> +++ b/include/linux/gunyah.h
> @@ -8,10 +8,67 @@
>
> #include <linux/bitfield.h>
> #include <linux/errno.h>
> +#include <linux/interrupt.h>
> #include <linux/limits.h>
> +#include <linux/mailbox_controller.h>
> +#include <linux/mailbox_client.h>
> #include <linux/types.h>
>
> -/* Common Gunyah macros */
> +/* 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_ret; /* Linux error, not GH_STATUS_* */
> + 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 */
> +
> #define GH_CAPID_INVAL U64_MAX
> #define GH_VMID_ROOT_VM 0xff
>