Re: [PATCH v5 09/13] mailbox: Add Gunyah message queue mailbox

Dmitry Baryshkov
2022-10-12T21:47:38Z

On 11/10/2022 03:08, 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>
> ---
> MAINTAINERS | 2 +
> drivers/mailbox/Kconfig | 10 ++
> drivers/mailbox/Makefile | 2 +
> drivers/mailbox/gunyah-msgq.c | 254 ++++++++++++++++++++++++++++++++++
> drivers/virt/gunyah/Kconfig | 2 +
> include/linux/gunyah.h | 67 +++++++++
> 6 files changed, 337 insertions(+)
> create mode 100644 drivers/mailbox/gunyah-msgq.c
> create mode 100644 include/linux/gunyah.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c5458aeec023..599804836d05 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8888,8 +8888,10 @@ F: Documentation/ABI/testing/sysfs-hypervisor-gunyah
> 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/asm-generic/gunyah.h
> +F: include/linux/gunyah.h
>
> HABANALABS PCI DRIVER
> M: Oded Gabbay <ogabbay@kernel.org>
> 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
> + 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-$(CONFIG_GUNYAH) += gunyah-msgq.o
> +
> obj-$(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..f0cd96920c64
> --- /dev/null
> +++ b/drivers/mailbox/gunyah-msgq.c
> @@ -0,0 +1,254 @@
> +// 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 gunyah_msgq, mbox))
> +
> +static inline bool gh_msgq_has_tx(struct gunyah_msgq *msgq)
> +{
> + return msgq->tx_ghrsc.type == GUNYAH_RESOURCE_TYPE_MSGQ_TX;
> +}
> +
> +static inline bool gh_msgq_has_rx(struct gunyah_msgq *msgq)
> +{
> + return msgq->rx_ghrsc.type == GUNYAH_RESOURCE_TYPE_MSGQ_RX;
> +}
> +
> +static ssize_t __gh_msgq_recv(struct gunyah_msgq *msgq, void *buff, size_t size, bool *ready)
> +{
> + unsigned long gh_err;
> + size_t recv_size;
> + ssize_t ret;
> +
> + gh_err = gh_hypercall_msgq_recv(msgq->rx_ghrsc.capid, (uintptr_t)buff, size,
> + &recv_size, ready);
> + switch (gh_err) {
> + case GH_ERROR_OK:
> + ret = recv_size;
> + break;
> + case GH_ERROR_MSGQUEUE_EMPTY:
> + ret = -EAGAIN;
> + *ready = false;
> + break;
> + default:
> + ret = gh_remap_error(gh_err);
> + break;
> + }
> +
> + return ret;
> +}
> +
> +static irqreturn_t gh_msgq_rx_irq_handler(int irq, void *data)
> +{
> + struct gunyah_msgq *msgq = data;
> + struct gunyah_msgq_rx_data rx_data;
> + ssize_t ret;
> + bool more;
> +
> + do {
> + ret = __gh_msgq_recv(msgq, &rx_data.data, sizeof(rx_data.data), &more);

Inline the call please.

> +
> + if (ret >= 0) {
> + rx_data.length = ret;
> + mbox_chan_received_data(gunyah_msgq_chan(msgq), &rx_data);
> + } else if (ret != -EAGAIN)
> + pr_warn("Failed to receive data from msgq for %s: %ld\n",
> + msgq->mbox.dev ? dev_name(msgq->mbox.dev) : "", ret);
> + } while (ret >= 0);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t gh_msgq_tx_irq_handler(int irq, void *data)
> +{
> + struct gunyah_msgq *msgq = data;
> +
> + mbox_chan_txdone(gunyah_msgq_chan(msgq), 0);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static void gh_msgq_txdone_tasklet(unsigned long data)
> +{
> + struct gunyah_msgq *msgq = (struct gunyah_msgq *)data;
> +
> + mbox_chan_txdone(gunyah_msgq_chan(msgq), msgq->last_status);

I don't quite get this. Why do you need both an IRQ and a tasklet?

> +}
> +
> +static int __gh_msgq_send(struct gunyah_msgq *msgq, void *buff, size_t size, u64 tx_flags)
> +{
> + unsigned long gh_err;
> + ssize_t ret;
> + bool ready;
> +
> + gh_err = gh_hypercall_msgq_send(msgq->tx_ghrsc.capid, size, (uintptr_t)buff, tx_flags,
> + &ready);
> + switch (gh_err) {
> + case GH_ERROR_OK:
> + ret = !ready;
> + break;
> + case GH_ERROR_MSGQUEUE_FULL:
> + ret = -EAGAIN;
> + break;
> + default:
> + /* Not sure how to propagate these out to client. If we get here, nobody is going
> + * to trigger a retry
> + */
> + ret = gh_remap_error(gh_err);
> + break;
> + }
> +
> + return ret;
> +}
> +
> +static int gh_msgq_send_data(struct mbox_chan *chan, void *data)
> +{
> + struct gunyah_msgq *msgq = mbox_chan_to_msgq(chan);
> + struct gunyah_msgq_tx_data *msgq_data = data;
> + u64 tx_flags = 0;
> + int ret;
> +
> + if (msgq_data->push)
> + tx_flags |= GH_HYPERCALL_MSGQ_TX_FLAGS_PUSH;
> +
> + ret = __gh_msgq_send(msgq, msgq_data->data, msgq_data->length, tx_flags);

Inline the call.

> +
> + /**
> + * EAGAIN: message didn't send.
> + * ret = 1: message sent, but now the message queue is full and we can't send any more msgs.
> + * Either way, don't report that this message is done.
> + */
> + if (ret == -EAGAIN || ret == 1)
> + return ret;

'1' doesn't seem to be a valid return code for _send_data.

Also it would be logical to return any error here, not just -EAGAIN.

> +
> + /**
> + * Mailbox framework requires that tx done happens asynchronously to sending the message
> + * IOW, a notification that the message was sent happens after sending the message.
> + * To work around this, defer the txdone to a tasklet.
> + */
> + msgq->last_status = ret;
> + tasklet_schedule(&msgq->txdone_tasklet);
> +
> + return 0;
> +}
> +
> +struct mbox_chan_ops gunyah_msgq_ops = {
> + .send_data = gh_msgq_send_data,
> +};
> +
> +/**
> + * gunyah_msgq_init() - Initialize a Gunyah message queue with an mbox_client
> + * @parent: optional, device parent used for the mailbox controller
> + * @msgq: Pointer to the gunyah_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,
> + * the client can send messages with mbox_send_message(gunyah_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 gunyah_msgq_rx_data will be replaced/destroyed
> + * after the callback.
> + *
> + * Returns - 0 on success, negative otherwise
> + */
> +int gunyah_msgq_init(struct device *parent, struct gunyah_msgq *msgq, struct mbox_client *cl,
> + struct gunyah_resource *tx_ghrsc, struct gunyah_resource *rx_ghrsc)

Are the message queues allocated/created dynamically or statically? If
the later is true, please use devm_request(_threaded)_irq and devm_kzalloc.

> +{
> + 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;
> +
> + msgq->tx_ghrsc = *tx_ghrsc;
> + msgq->rx_ghrsc = *rx_ghrsc;

Why? You can just turn msg->tx_ghrsc/rx_ghrsc into pointers and just
assign them here.

> +
> + msgq->mbox.dev = parent;
> + msgq->mbox.ops = &gunyah_msgq_ops;
> + msgq->mbox.chans = kcalloc(1, sizeof(*msgq->mbox.chans), GFP_KERNEL);

kzalloc?

> + msgq->mbox.num_chans = 1;
> + msgq->mbox.txdone_irq = true;
> +
> + if (gh_msgq_has_tx(msgq)) {
> + ret = request_irq(msgq->tx_ghrsc.irq, gh_msgq_tx_irq_handler, 0, "gh_msgq_tx",
> + msgq);
> + if (ret)
> + goto err_chans;
> + }
> +
> + if (gh_msgq_has_rx(msgq)) {
> + 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_init(&msgq->txdone_tasklet, gh_msgq_txdone_tasklet, (unsigned long)msgq);
> +
> + ret = mbox_controller_register(&msgq->mbox);
> + if (ret)
> + goto err_rx_irq;
> +
> + ret = mbox_bind_client(gunyah_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))
> + free_irq(msgq->rx_ghrsc.irq, msgq);
> +err_tx_irq:
> + if (gh_msgq_has_tx(msgq))
> + free_irq(msgq->tx_ghrsc.irq, msgq);
> +err_chans:
> + kfree(msgq->mbox.chans);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(gunyah_msgq_init);
> +
> +void gunyah_msgq_remove(struct gunyah_msgq *msgq)
> +{
> + if (gh_msgq_has_tx(msgq))
> + free_irq(msgq->tx_ghrsc.irq, msgq);

Missing:

+ if (gh_msgq_has_rx(msgq))
+ free_irq(msgq->rx_ghrsc.irq, msgq);

> +
> + kfree(msgq->mbox.chans);
> +}
> +EXPORT_SYMBOL_GPL(gunyah_msgq_remove);
> +
> +
> +static int __init gh_msgq_init(void)
> +{
> + if (GH_API_INFO_API_VERSION(gunyah_api.api_info) != GUNYAH_API_V1) {
> + pr_warn("Unrecognized gunyah version: %llu. Currently supported: %d\n",
> + GH_API_INFO_API_VERSION(gunyah_api.api_info), GUNYAH_API_V1);
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +module_init(gh_msgq_init);
> +
> +static void __exit gh_msgq_exit(void)
> +{
> +}
> +module_exit(gh_msgq_exit);

Not needed

> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Gunyah Message Queue Driver");
> diff --git a/drivers/virt/gunyah/Kconfig b/drivers/virt/gunyah/Kconfig
> index 7ac917e0aa3f..f4c822a82f1a 100644
> --- a/drivers/virt/gunyah/Kconfig
> +++ b/drivers/virt/gunyah/Kconfig
> @@ -4,6 +4,8 @@ config GUNYAH
> tristate "Gunyah Virtualization drivers"
> depends on ARM64
> select AUXILIARY_BUS
> + select MAILBOX
> + select GUNYAH_MESSAGE_QUEUES
> help
> The Gunyah drivers are the helper interfaces that runs in a guest VM
> such as basic inter-VM IPC and signaling mechanisms, and higher level
> diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
> new file mode 100644
> index 000000000000..0e9709555c79
> --- /dev/null
> +++ b/include/linux/gunyah.h
> @@ -0,0 +1,67 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#ifndef _GUNYAH_H
> +#define _GUNYAH_H
> +
> +#include <linux/mailbox_controller.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/interrupt.h>
> +
> +#include <asm-generic/gunyah.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 gunyah_msgq_tx_data {
> + size_t length;
> + bool push;
> + char data[];
> +};
> +
> +struct gunyah_msgq_rx_data {
> + size_t length;
> + char data[GH_MSGQ_MAX_MSG_SIZE];
> +};
> +
> +struct gunyah_msgq {
> + struct gunyah_resource tx_ghrsc;
> + struct gunyah_resource rx_ghrsc;
> +
> + /* msgq private */
> + int last_status;
> + struct mbox_controller mbox;
> + struct tasklet_struct txdone_tasklet;
> +};
> +
> +
> +int gunyah_msgq_init(struct device *parent, struct gunyah_msgq *msgq, struct mbox_client *cl,
> + struct gunyah_resource *tx_ghrsc, struct gunyah_resource *rx_ghrsc);
> +void gunyah_msgq_remove(struct gunyah_msgq *msgq);
> +
> +static inline struct mbox_chan *gunyah_msgq_chan(struct gunyah_msgq *msgq)
> +{
> + return &msgq->mbox.chans[0];
> +}
> +
> +#endif

--
With best wishes
Dmitry