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;

        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;
}