Re: [PATCH v4 12/14] gunyah: rsc_mgr: Add RPC for console services

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Sep 28, 2022 at 12:56:31PM -0700, Elliot Berman wrote:
> Gunyah resource manager defines a simple API for virtual machine log
> sharing with the console service. A VM's own log can be opened by using
> GH_VMID_SELF. Another VM's log can be accessed via its VMID. Once
> opened, characters can be written to the log with a write command.
> Characters are received with resource manager notifications (using ID
> GH_RM_NOTIF_VM_CONSOLE_CHARS).
> 
> These high level rpc calls are kept in
> drivers/virt/gunyah/rsc_mgr_rpc.c. Future RPC calls, e.g. to launch a VM
> will also be maintained in this file.
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> ---
>  drivers/virt/gunyah/Makefile      |   2 +-
>  drivers/virt/gunyah/rsc_mgr.h     |  22 +++++
>  drivers/virt/gunyah/rsc_mgr_rpc.c | 151 ++++++++++++++++++++++++++++++
>  include/linux/gunyah_rsc_mgr.h    |  16 ++++
>  4 files changed, 190 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/virt/gunyah/rsc_mgr_rpc.c
> 
> diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile
> index 7c512490f921..73339ed445b3 100644
> --- a/drivers/virt/gunyah/Makefile
> +++ b/drivers/virt/gunyah/Makefile
> @@ -1,5 +1,5 @@
>  gunyah-y += sysfs.o
>  obj-$(CONFIG_GUNYAH) += gunyah.o
>  
> -gunyah_rsc_mgr-y += rsc_mgr.o
> +gunyah_rsc_mgr-y += rsc_mgr.o rsc_mgr_rpc.o
>  obj-$(CONFIG_GUNYAH_RESORUCE_MANAGER) += gunyah_rsc_mgr.o
> diff --git a/drivers/virt/gunyah/rsc_mgr.h b/drivers/virt/gunyah/rsc_mgr.h
> index e4f2499267bf..deb884979209 100644
> --- a/drivers/virt/gunyah/rsc_mgr.h
> +++ b/drivers/virt/gunyah/rsc_mgr.h
> @@ -28,6 +28,28 @@
>  #define GH_RM_ERROR_IRQ_INUSE		0x10
>  #define GH_RM_ERROR_IRQ_RELEASED	0x11
>  
> +/* Message IDs: VM Management */
> +#define GH_RM_RPC_VM_GET_VMID			0x56000024
> +
> +/* Message IDs: VM Services */
> +#define GH_RM_RPC_VM_CONSOLE_OPEN_ID		0x56000081
> +#define GH_RM_RPC_VM_CONSOLE_CLOSE_ID		0x56000082
> +#define GH_RM_RPC_VM_CONSOLE_WRITE_ID		0x56000083
> +#define GH_RM_RPC_VM_CONSOLE_FLUSH_ID		0x56000084
> +
> +/* Call: CONSOLE_OPEN, CONSOLE_CLOSE, CONSOLE_FLUSH */
> +struct gh_vm_console_common_req {
> +	u16 vmid;
> +	u16 reserved0;
> +} __packed;
> +
> +/* Call: CONSOLE_WRITE */
> +struct gh_vm_console_write_req {
> +	u16 vmid;
> +	u16 num_bytes;
> +	u8 data[0];
> +} __packed;
> +
>  int gh_rm_call(u32 message_id, void *req_buff, size_t req_buff_size,
>  		void **resp_buf, size_t *resp_buff_size);
>  
> diff --git a/drivers/virt/gunyah/rsc_mgr_rpc.c b/drivers/virt/gunyah/rsc_mgr_rpc.c
> new file mode 100644
> index 000000000000..8238c6ef301f
> --- /dev/null
> +++ b/drivers/virt/gunyah/rsc_mgr_rpc.c
> @@ -0,0 +1,151 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#define pr_fmt(fmt) "gh_rsc_mgr: " fmt
> +
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <linux/printk.h>
> +#include <linux/gunyah_rsc_mgr.h>
> +
> +#include "rsc_mgr.h"
> +
> +/**
> + * gh_rm_get_vmid() - Retrieve VMID of this virtual machine
> + * @vmid: Filled with the VMID of this VM
> + */
> +int gh_rm_get_vmid(u16 *vmid)
> +{
> +	void *resp;
> +	size_t resp_size;
> +	int ret;
> +	int payload = 0;
> +
> +	ret = gh_rm_call(GH_RM_RPC_VM_GET_VMID, &payload, sizeof(payload), &resp, &resp_size);
> +	if (ret)
> +		return ret;
> +
> +	if (resp_size != sizeof(*vmid))
> +		return -EIO;
> +	*vmid = *(u16 *)resp;
> +	kfree(resp);
> +
> +	return ret;
> +}
> +
> +/**
> + * gh_rm_console_open() - Open a console with a VM
> + * @vmid: VMID of the other VM whose console to open. If VMID is GH_VMID_SELF, the
> + *        console associated with this VM is opened.
> + */
> +int gh_rm_console_open(u16 vmid)
> +{
> +	void *resp;
> +	struct gh_vm_console_common_req req_payload = {0};
> +	size_t resp_size;
> +	int ret;
> +
> +	req_payload.vmid = vmid;
> +
> +	ret = gh_rm_call(GH_RM_RPC_VM_CONSOLE_OPEN_ID,
> +			  &req_payload, sizeof(req_payload),
> +			  &resp, &resp_size);
> +	kfree(resp);
> +
> +	if (!ret && resp_size)
> +		pr_warn("Received unexpected payload for CONSOLE_OPEN: %lu\n", resp_size);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(gh_rm_console_open);
> +
> +/**
> + * gh_rm_console_close() - Close a console with a VM
> + * @vmid: The vmid of the vm whose console to close.
> + */
> +int gh_rm_console_close(u16 vmid)
> +{
> +	void *resp;
> +	struct gh_vm_console_common_req req_payload = {0};
> +	size_t resp_size;
> +	int ret;
> +
> +	req_payload.vmid = vmid;
> +
> +	ret = gh_rm_call(GH_RM_RPC_VM_CONSOLE_CLOSE_ID,
> +			  &req_payload, sizeof(req_payload),
> +			  &resp, &resp_size);
> +	kfree(resp);
> +
> +	if (!ret && resp_size)
> +		pr_warn("Received unexpected payload for CONSOLE_CLOSE: %lu\n", resp_size);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(gh_rm_console_close);
> +
> +/**
> + * gh_rm_console_write() - Write to a VM's console
> + * @vmid: The vmid of the vm whose console to write to.
> + * @buf: Buffer to write to the VM's console
> + * @size: Size of the buffer
> + */
> +int gh_rm_console_write(u16 vmid, const char *buf, size_t size)
> +{
> +	void *resp;
> +	struct gh_vm_console_write_req *req_payload;
> +	size_t resp_size;
> +	int ret = 0;
> +	size_t req_payload_size = sizeof(*req_payload) + size;
> +
> +	if (size < 1 || size > (U32_MAX - sizeof(*req_payload)))
> +		return -EINVAL;
> +
> +	req_payload = kzalloc(req_payload_size, GFP_KERNEL);
> +
> +	if (!req_payload)
> +		return -ENOMEM;
> +
> +	req_payload->vmid = vmid;
> +	req_payload->num_bytes = size;
> +	memcpy(req_payload->data, buf, size);
> +
> +	ret = gh_rm_call(GH_RM_RPC_VM_CONSOLE_WRITE_ID,
> +		   req_payload, req_payload_size,
> +		   &resp, &resp_size);
> +	kfree(req_payload);
> +	kfree(resp);
> +
> +	if (!ret && resp_size)
> +		pr_warn("Received unexpected payload for CONSOLE_WRITE: %lu\n", resp_size);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(gh_rm_console_write);
> +
> +/**
> + * gh_rm_console_flush() - Flush a console with a VM
> + * @vmid: The vmid of the vm whose console to flush
> + */
> +int gh_rm_console_flush(u16 vmid)
> +{
> +	void *resp;
> +	struct gh_vm_console_common_req req_payload = {0};
> +	size_t resp_size;
> +	int ret;
> +
> +	req_payload.vmid = vmid;
> +
> +	ret = gh_rm_call(GH_RM_RPC_VM_CONSOLE_FLUSH_ID,
> +			  &req_payload, sizeof(req_payload),
> +			  &resp, &resp_size);
> +	kfree(resp);
> +
> +	if (!ret && resp_size)
> +		pr_warn("Received unexpected payload for CONSOLE_FLUSH: %lu\n", resp_size);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(gh_rm_console_flush);
> diff --git a/include/linux/gunyah_rsc_mgr.h b/include/linux/gunyah_rsc_mgr.h
> index b3b37225b7fb..f831ca921c26 100644
> --- a/include/linux/gunyah_rsc_mgr.h
> +++ b/include/linux/gunyah_rsc_mgr.h
> @@ -23,4 +23,20 @@ struct gh_rm_notification {
>  int gh_rm_register_notifier(struct notifier_block *nb);
>  int gh_rm_unregister_notifier(struct notifier_block *nb);
>  
> +/* Notification type Message IDs */
> +#define GH_RM_NOTIF_VM_CONSOLE_CHARS	0x56100080
> +
> +struct gh_rm_notif_vm_console_chars {
> +	u16 vmid;
> +	u16 num_bytes;
> +	u8 bytes[0];

Please do not use [0] for new structures, otherwise we will just have to
fix them up again as we are trying to get rid of all of these from the
kernel. Just use "bytes[];" instead.

thanks,

greg k-h