examples/vhost_scsi/vhost_scsi.c

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2010-2017 Intel Corporation
 */

#include <stdint.h>
#include <unistd.h>
#include <stdbool.h>
#include <signal.h>
#include <assert.h>
#include <semaphore.h>
#include <linux/virtio_scsi.h>
#include <linux/virtio_ring.h>

#include <rte_atomic.h>
#include <rte_cycles.h>
#include <rte_log.h>
#include <rte_malloc.h>
#include <rte_vhost.h>

#include "vhost_scsi.h"
#include "scsi_spec.h"

#define VIRTIO_SCSI_FEATURES ((1 << VIRTIO_F_NOTIFY_ON_EMPTY) |\
                  (1 << VIRTIO_SCSI_F_INOUT) |\
                  (1 << VIRTIO_SCSI_F_CHANGE))

/* Path to folder where character device will be created. Can be set by user. */
static char dev_pathname[PATH_MAX] = "";

static struct vhost_scsi_ctrlr *g_vhost_ctrlr;
static int g_should_stop;
static sem_t exit_sem;

static struct vhost_scsi_ctrlr *
vhost_scsi_ctrlr_find(__rte_unused const char *ctrlr_name)
{
    /* currently we only support 1 socket file fd */
    return g_vhost_ctrlr;
}

static uint64_t gpa_to_vva(int vid, uint64_t gpa, uint64_t *len)
{
    char path[PATH_MAX];
    struct vhost_scsi_ctrlr *ctrlr;
    int ret = 0;

    ret = rte_vhost_get_ifname(vid, path, PATH_MAX);
    if (ret) {
        fprintf(stderr, "Cannot get socket name\n");
        assert(ret != 0);
    }

    ctrlr = vhost_scsi_ctrlr_find(path);
    if (!ctrlr) {
        fprintf(stderr, "Controller is not ready\n");
        assert(ctrlr != NULL);
    }

    assert(ctrlr->mem != NULL);

    return rte_vhost_va_from_guest_pa(ctrlr->mem, gpa, len);
}

static struct vring_desc *
descriptor_get_next(struct vring_desc *vq_desc, struct vring_desc *cur_desc)
{
    return &vq_desc[cur_desc->next];
}

static bool
descriptor_has_next(struct vring_desc *cur_desc)
{
    return !!(cur_desc->flags & VRING_DESC_F_NEXT);
}

static bool
descriptor_is_wr(struct vring_desc *cur_desc)
{
    return !!(cur_desc->flags & VRING_DESC_F_WRITE);
}

static void
submit_completion(struct vhost_scsi_task *task, uint32_t q_idx)
{
    struct rte_vhost_vring *vq;
    struct vring_used *used;

    vq = task->vq;
    used = vq->used;
    /* Fill out the next entry in the "used" ring.  id = the
     * index of the descriptor that contained the SCSI request.
     * len = the total amount of data transferred for the SCSI
     * request. We must report the correct len, for variable
     * length SCSI CDBs, where we may return less data than
     * allocated by the guest VM.
     */
    used->ring[used->idx & (vq->size - 1)].id = task->req_idx;
    used->ring[used->idx & (vq->size - 1)].len = task->data_len;
    used->idx++;

    /* Send an interrupt back to the guest VM so that it knows
     * a completion is ready to be processed.
     */
    rte_vhost_vring_call(task->bdev->vid, q_idx);
}

static void
vhost_process_read_payload_chain(struct vhost_scsi_task *task)
{
    void *data;
    uint64_t chunck_len;

    task->iovs_cnt = 0;
    chunck_len = task->desc->len;
    task->resp = (void *)(uintptr_t)gpa_to_vva(task->bdev->vid,
                           task->desc->addr,
                           &chunck_len);
    if (!task->resp || chunck_len != task->desc->len) {
        fprintf(stderr, "failed to translate desc address.\n");
        return;
    }

    while (descriptor_has_next(task->desc)) {
        task->desc = descriptor_get_next(task->vq->desc, task->desc);
        chunck_len = task->desc->len;
        data = (void *)(uintptr_t)gpa_to_vva(task->bdev->vid,
                             task->desc->addr,
                             &chunck_len);
        if (!data || chunck_len != task->desc->len) {
            fprintf(stderr, "failed to translate desc address.\n");
            return;
        }

        task->iovs[task->iovs_cnt].iov_base = data;
        task->iovs[task->iovs_cnt].iov_len = task->desc->len;
        task->data_len += task->desc->len;
        task->iovs_cnt++;
    }
}

static void
vhost_process_write_payload_chain(struct vhost_scsi_task *task)
{
    void *data;
    uint64_t chunck_len;

    task->iovs_cnt = 0;

    do {
        chunck_len = task->desc->len;
        data = (void *)(uintptr_t)gpa_to_vva(task->bdev->vid,
                             task->desc->addr,
                             &chunck_len);
        if (!data || chunck_len != task->desc->len) {
            fprintf(stderr, "failed to translate desc address.\n");
            return;
        }

        task->iovs[task->iovs_cnt].iov_base = data;
        task->iovs[task->iovs_cnt].iov_len = task->desc->len;
        task->data_len += task->desc->len;
        task->iovs_cnt++;
        task->desc = descriptor_get_next(task->vq->desc, task->desc);
    } while (descriptor_has_next(task->desc));

    chunck_len = task->desc->len;
    task->resp = (void *)(uintptr_t)gpa_to_vva(task->bdev->vid,
                           task->desc->addr,
                           &chunck_len);
    if (!task->resp || chunck_len != task->desc->len)
        fprintf(stderr, "failed to translate desc address.\n");
}

static struct vhost_block_dev *
vhost_scsi_bdev_construct(const char *bdev_name, const char *bdev_serial,
              uint32_t blk_size, uint64_t blk_cnt,
              bool wce_enable)
{
    struct vhost_block_dev *bdev;

    bdev = rte_zmalloc(NULL, sizeof(*bdev), RTE_CACHE_LINE_SIZE);
    if (!bdev)
        return NULL;

    strncpy(bdev->name, bdev_name, sizeof(bdev->name));
    strncpy(bdev->product_name, bdev_serial, sizeof(bdev->product_name));
    bdev->blocklen = blk_size;
    bdev->blockcnt = blk_cnt;
    bdev->write_cache = wce_enable;

    /* use memory as disk storage space */
    bdev->data = rte_zmalloc(NULL, blk_cnt * blk_size, 0);
    if (!bdev->data) {
        fprintf(stderr, "no enough reseverd huge memory for disk\n");
        return NULL;
    }

    return bdev;
}

static void
process_requestq(struct vhost_scsi_ctrlr *ctrlr, uint32_t q_idx)
{
    int ret;
    struct vhost_scsi_queue *scsi_vq;
    struct rte_vhost_vring *vq;

    scsi_vq = &ctrlr->bdev->queues[q_idx];
    vq = &scsi_vq->vq;
    ret = rte_vhost_get_vhost_vring(ctrlr->bdev->vid, q_idx, vq);
    assert(ret == 0);

    while (vq->avail->idx != scsi_vq->last_used_idx) {
        int req_idx;
        uint16_t last_idx;
        struct vhost_scsi_task *task;
        uint64_t chunck_len;

        last_idx = scsi_vq->last_used_idx & (vq->size - 1);
        req_idx = vq->avail->ring[last_idx];

        task = rte_zmalloc(NULL, sizeof(*task), 0);
        assert(task != NULL);

        task->ctrlr = ctrlr;
        task->bdev = ctrlr->bdev;
        task->vq = vq;
        task->req_idx = req_idx;
        task->desc = &task->vq->desc[task->req_idx];

        /* does not support indirect descriptors */
        assert((task->desc->flags & VRING_DESC_F_INDIRECT) == 0);
        scsi_vq->last_used_idx++;

        chunck_len = task->desc->len;
        task->req = (void *)(uintptr_t)gpa_to_vva(task->bdev->vid,
                              task->desc->addr,
                              &chunck_len);
        if (!task->req || chunck_len != task->desc->len) {
            fprintf(stderr, "failed to translate desc address.\n");
            return;
        }

        task->desc = descriptor_get_next(task->vq->desc, task->desc);
        if (!descriptor_has_next(task->desc)) {
            task->dxfer_dir = SCSI_DIR_NONE;
            chunck_len = task->desc->len;
            task->resp = (void *)(uintptr_t)
                          gpa_to_vva(task->bdev->vid,
                             task->desc->addr,
                             &chunck_len);
            if (!task->resp || chunck_len != task->desc->len) {
                fprintf(stderr, "failed to translate desc address.\n");
                return;
            }
        } else if (!descriptor_is_wr(task->desc)) {
            task->dxfer_dir = SCSI_DIR_TO_DEV;
            vhost_process_write_payload_chain(task);
        } else {
            task->dxfer_dir = SCSI_DIR_FROM_DEV;
            vhost_process_read_payload_chain(task);
        }

        ret = vhost_bdev_process_scsi_commands(ctrlr->bdev, task);
        if (ret) {
            /* invalid response */
            task->resp->response = VIRTIO_SCSI_S_BAD_TARGET;
        } else {
            /* successfully */
            task->resp->response = VIRTIO_SCSI_S_OK;
            task->resp->status = 0;
            task->resp->resid = 0;
        }
        submit_completion(task, q_idx);
        rte_free(task);
    }
}

/* Main framework for processing IOs */
static void *
ctrlr_worker(void *arg)
{
    uint32_t idx, num;
    struct vhost_scsi_ctrlr *ctrlr = (struct vhost_scsi_ctrlr *)arg;
    cpu_set_t cpuset;
    pthread_t thread;

    if (ctrlr == NULL || ctrlr->bdev == NULL) {
        fprintf(stderr, "%s: Error, invalid argument passed to worker thread\n",
                __func__);
        exit(0);
    }

    thread = pthread_self();
    CPU_ZERO(&cpuset);
    CPU_SET(0, &cpuset);
    pthread_setaffinity_np(thread, sizeof(cpu_set_t), &cpuset);

    num =  rte_vhost_get_vring_num(ctrlr->bdev->vid);
    fprintf(stdout, "Ctrlr Worker Thread Started with %u Vring\n", num);

    if (num != NUM_OF_SCSI_QUEUES) {
        fprintf(stderr, "Only 1 IO queue are supported\n");
        exit(0);
    }

    while (!g_should_stop && ctrlr->bdev != NULL) {
        /* At least 3 vrings, currently only can support 1 IO queue
         * Queue 2 for IO queue, does not support TMF and hotplug
         * for the example application now
         */
        for (idx = 2; idx < num; idx++)
            process_requestq(ctrlr, idx);
    }

    fprintf(stdout, "Ctrlr Worker Thread Exiting\n");
    sem_post(&exit_sem);
    return NULL;
}

static int
new_device(int vid)
{
    char path[PATH_MAX];
    struct vhost_scsi_ctrlr *ctrlr;
    struct vhost_scsi_queue *scsi_vq;
    struct rte_vhost_vring *vq;
    pthread_t tid;
    int i, ret;

    ret = rte_vhost_get_ifname(vid, path, PATH_MAX);
    if (ret) {
        fprintf(stderr, "Cannot get socket name\n");
        return -1;
    }

    ctrlr = vhost_scsi_ctrlr_find(path);
    if (!ctrlr) {
        fprintf(stderr, "Controller is not ready\n");
        return -1;
    }

    ret = rte_vhost_get_mem_table(vid, &ctrlr->mem);
    if (ret) {
        fprintf(stderr, "Get Controller memory region failed\n");
        return -1;
    }
    assert(ctrlr->mem != NULL);

    /* hardcoded block device information with 128MiB */
    ctrlr->bdev = vhost_scsi_bdev_construct("malloc0", "vhost_scsi_malloc0",
                        4096, 32768, 0);
    if (!ctrlr->bdev)
        return -1;

    ctrlr->bdev->vid = vid;

    /* Disable Notifications */
    for (i = 0; i < NUM_OF_SCSI_QUEUES; i++) {
        rte_vhost_enable_guest_notification(vid, i, 0);
        /* restore used index */
        scsi_vq = &ctrlr->bdev->queues[i];
        vq = &scsi_vq->vq;
        ret = rte_vhost_get_vhost_vring(ctrlr->bdev->vid, i, vq);
        assert(ret == 0);
        scsi_vq->last_used_idx = vq->used->idx;
        scsi_vq->last_avail_idx = vq->used->idx;
    }

    g_should_stop = 0;
    fprintf(stdout, "New Device %s, Device ID %d\n", path, vid);
    if (pthread_create(&tid, NULL, &ctrlr_worker, ctrlr) < 0) {
        fprintf(stderr, "Worker Thread Started Failed\n");
        return -1;
    }
    pthread_detach(tid);
    return 0;
}

static void
destroy_device(int vid)
{
    char path[PATH_MAX];
    struct vhost_scsi_ctrlr *ctrlr;

    rte_vhost_get_ifname(vid, path, PATH_MAX);
    fprintf(stdout, "Destroy %s Device ID %d\n", path, vid);
    ctrlr = vhost_scsi_ctrlr_find(path);
    if (!ctrlr) {
        fprintf(stderr, "Destroy Ctrlr Failed\n");
        return;
    }
    ctrlr->bdev = NULL;
    g_should_stop = 1;

    sem_wait(&exit_sem);
}

static const struct vhost_device_ops vhost_scsi_device_ops = {
    .new_device =  new_device,
    .destroy_device = destroy_device,
};

static struct vhost_scsi_ctrlr *
vhost_scsi_ctrlr_construct(const char *ctrlr_name)
{
    int ret;
    struct vhost_scsi_ctrlr *ctrlr;
    char *path;
    char cwd[PATH_MAX];

    /* always use current directory */
    path = getcwd(cwd, PATH_MAX);
    if (!path) {
        fprintf(stderr, "Cannot get current working directory\n");
        return NULL;
    }
    snprintf(dev_pathname, sizeof(dev_pathname), "%s/%s", path, ctrlr_name);

    if (access(dev_pathname, F_OK) != -1) {
        if (unlink(dev_pathname) != 0)
            rte_exit(EXIT_FAILURE, "Cannot remove %s.\n",
                 dev_pathname);
    }

    if (rte_vhost_driver_register(dev_pathname, 0) != 0) {
        fprintf(stderr, "socket %s already exists\n", dev_pathname);
        return NULL;
    }

    fprintf(stdout, "socket file: %s created\n", dev_pathname);

    ret = rte_vhost_driver_set_features(dev_pathname, VIRTIO_SCSI_FEATURES);
    if (ret != 0) {
        fprintf(stderr, "Set vhost driver features failed\n");
        return NULL;
    }

    ctrlr = rte_zmalloc(NULL, sizeof(*ctrlr), RTE_CACHE_LINE_SIZE);
    if (!ctrlr)
        return NULL;

    rte_vhost_driver_callback_register(dev_pathname,
                       &vhost_scsi_device_ops);

    return ctrlr;
}

static void
signal_handler(__rte_unused int signum)
{

    if (access(dev_pathname, F_OK) == 0)
        unlink(dev_pathname);
    exit(0);
}

int main(int argc, char *argv[])
{
    int ret;

    signal(SIGINT, signal_handler);

    /* init EAL */
    ret = rte_eal_init(argc, argv);
    if (ret < 0)
        rte_exit(EXIT_FAILURE, "Error with EAL initialization\n");

    g_vhost_ctrlr = vhost_scsi_ctrlr_construct("vhost.socket");
    if (g_vhost_ctrlr == NULL) {
        fprintf(stderr, "Construct vhost scsi controller failed\n");
        return 0;
    }

    if (sem_init(&exit_sem, 0, 0) < 0) {
        fprintf(stderr, "Error init exit_sem\n");
        return -1;
    }

    rte_vhost_driver_start(dev_pathname);

    /* loop for exit the application */
    while (1)
        sleep(1);

    return 0;
}