virtio-loopback-driver - multi-device supportHEADmaster

Updates [v1]:
- The driver to handle multiple adapter instances.
- The source code is restructured and splitted into:
  "virtio_loopback_driver.c" and "virtio_loopback_device.c".
- Notification mechanism is based on workqueues

Updates [v2]:
- Update module final name to 'virtio_loopback'
- Update the README file, add tested platforms
- Fix indents, typos

Bug-AGL: SPEC-4834

Change-Id: Ifef4cb222652c3e8584849d257d84abc7c7ba1b5
Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>

1 files changed, 253 insertions, 0 deletions

diff --git a/virtio_loopback_driver.h b/virtio_loopback_driver.h
new file mode 100644
index 0000000..d0a744b
--- /dev/null
+++ b/virtio_loopback_driver.h
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2022-2024 Virtual Open Systems SAS.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+#ifndef __LOOPBACK_H__
+#define __LOOPBACK_H__
+
+#define DRIVER  "LOOPBACK"
+
+#include <linux/cdev.h>
+#include <linux/eventfd.h>
+#include <linux/fdtable.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/of_address.h>
+#include <linux/cpumask.h>
+#include <linux/smp.h>
+#include <linux/version.h>
+#include <linux/completion.h>
+
+/* MMIO includes */
+#include <linux/acpi.h>
+#include <linux/dma-mapping.h>
+#include <linux/highmem.h>
+#include <linux/io.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <uapi/linux/virtio_mmio.h>
+#include <linux/virtio_ring.h>
+
+#include <linux/kernel.h>
+#include <linux/pid.h>
+#include <linux/sched.h>
+#include <linux/rcupdate.h>
+#include <linux/kthread.h>
+
+/* mmap includes */
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+
+#include <linux/pagemap.h>
+#include <linux/delay.h>
+
+/* max Minor devices */
+#define MAX_DEV	1
+#define MAX_PDEV 100
+#define PDEV_TYPES 2
+
+/* Define mmap elements limit */
+#define MMAP_LIMIT	200
+
+/*
+ * The alignment to use between consumer and producer parts of vring.
+ * Currently hardcoded to the page size.
+ */
+#define VIRTIO_MMIO_VRING_ALIGN PAGE_SIZE
+
+#define to_virtio_loopback_device(ptr, field) \
+	container_of(ptr, struct virtio_loopback_device, field)
+
+/* mmap functionality */
+#ifndef VM_RESERVED
+#define VM_RESERVED (VM_DONTEXPAND | VM_DONTDUMP)
+#endif
+
+/* IOCTL defines */
+#define EFD_INIT _IOC(_IOC_WRITE, 'k', 1, sizeof(efd_data))
+#define WAKEUP _IOC(_IOC_WRITE, 'k', 2, 0)
+#define START_LOOPBACK _IOC(_IOC_WRITE, 'k', 3, sizeof(struct virtio_device_info_struct))
+#define IRQ _IOC(_IOC_WRITE, 'k', 4, sizeof(int))
+#define SHARE_VQS _IOC(_IOC_WRITE, 'k', 5, sizeof(uint32_t))
+#define SHARE_COM_STRUCT _IOC(_IOC_WRITE, 'k', 7, 0)
+
+/* Data structures */
+struct virtio_device_info_struct {
+	unsigned long magic;
+	unsigned long version;
+	unsigned long device_id;
+	unsigned long vendor;
+};
+
+struct virtio_neg {
+	uint64_t notification;
+	uint64_t data;
+	uint64_t size;
+	bool read;
+	atomic_t done;
+};
+
+struct share_mmap {
+	uint64_t pfn;
+	uint64_t vm_start;
+	uint32_t size;
+	uint32_t uid;
+	struct page *page;
+};
+
+struct mmap_data {
+	int mmap_index;
+	bool share_communication_struct;
+	bool share_vqs;
+	struct share_mmap share_mmap_list[MMAP_LIMIT];
+	int cur_ram_idx;
+	uint64_t sum_pgfaults;
+};
+
+/* vq related data */
+struct vq_data {
+	uint32_t vq_index;
+	uint64_t vq_pfns[16];
+	uint64_t vq_pfn;
+};
+
+/* Data describing each device private status */
+struct device_data {
+	/* Info needed for adapter ops */
+	struct mmap_info *info;
+	/* Waitqueue for the adapter */
+	wait_queue_head_t wq;
+	struct mutex read_write_lock;
+	struct eventfd_ctx *efd_ctx;
+	/*
+	 * If this variable is true then read/write should wait
+	 * the adapter to unlock this operation by sending an
+	 * eventfd. If it's equal to "false" then the operation
+	 * does not wait for adapter's confirmation.
+	 */
+	bool valid_eventfd;
+	/* vq data */
+	struct vq_data vq_data;
+};
+
+/* Data describing each entry of the driver */
+struct loopback_devices_array {
+	/* Array of probed devices */
+	struct virtio_loopback_device *devices[MAX_PDEV];
+	/* Number of available devices */
+	atomic_t device_num;
+	/* Registration completion */
+	struct completion reg_vl_dev_completion[MAX_PDEV];
+};
+
+/* Data concealed in the file private pointer */
+struct file_priv_data {
+	/* Device needed data */
+	struct device_data *dev_data;
+	/* mmap needed data */
+	struct mmap_data *mm_data;
+	/* Device info! */
+	struct virtio_device_info_struct device_info;
+	/* The vl_dev pointer for the irq */
+	struct virtio_loopback_device *vl_dev_irq;
+};
+
+struct virtio_loopback_device {
+	struct virtio_device vdev;
+	struct platform_device *pdev;
+	/* Corresponding data pointer */
+	struct device_data *data;
+
+	/* Status: -1 not initialized, 0 running, 1 paused */
+	int status;
+
+	void __iomem *base;
+	unsigned long version;
+
+	/* A list of queues so we can dispatch IRQs */
+	spinlock_t lock;
+	struct list_head virtqueues;
+
+	/* Notify list and work struct */
+	spinlock_t notify_q_lock;
+	struct list_head notify_list;
+	struct work_struct notify_work;
+};
+
+struct virtio_loopback_vq_info {
+	/* the actual virtqueue */
+	struct virtqueue *vq;
+	/* the list node for the virtqueues list */
+	struct list_head node;
+};
+
+/* Notify data*/
+struct notify_data {
+	uint32_t index;
+	struct list_head list;
+};
+
+/* Shared data structure between driver and user-space application */
+struct mmap_info {
+	void *data;
+	int reference;
+};
+
+/*
+ * This structure holds the eventfds shared between the driver
+ * and the user-space application.
+ */
+struct efd_data {
+	int efd[2];
+	int pid;
+};
+
+/* device data holder, this structure may be extended to hold additional data */
+struct loopback_device_data {
+	/*device Major number */
+	int dev_major;
+	/* sysfs class structure */
+	struct class *class;
+	struct cdev cdev;
+	/* Define workqueue for notifications */
+	struct workqueue_struct *notify_workqueue;
+};
+
+/* Global variables */
+extern struct loopback_device_data loopback_data;
+extern struct loopback_devices_array loopback_devices;
+extern struct platform_driver virtio_loopback_driver;
+
+/* Global functions */
+int insert_entry_data(struct virtio_loopback_device *vl_dev, int id);
+int loopback_register_virtio_dev(struct virtio_loopback_device *vl_dev);
+bool vl_interrupt(struct virtio_loopback_device *vl_dev, int irq);
+#if LINUX_VERSION_CODE > KERNEL_VERSION(6, 10, 8)
+void virtio_loopback_remove(struct platform_device *pdev);
+#else
+int virtio_loopback_remove(struct platform_device *pdev);
+#endif
+
+#endif /* __LOOPBACK_H__ */