examples/vhost_blk/vhost_blk_compat.c

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2010-2019 Intel Corporation
 */

#ifndef _VHOST_BLK_COMPAT_H_
#define _VHOST_BLK_COMPAT_H_

#include <sys/uio.h>
#include <stdint.h>
#include <linux/virtio_blk.h>
#include <linux/virtio_ring.h>

#include <rte_vhost.h>
#include "vhost_blk.h"
#include "blk_spec.h"

#define VHOST_MAX_VQUEUES   256
#define SPDK_VHOST_MAX_VQ_SIZE  1024

#define VHOST_USER_GET_CONFIG   24
#define VHOST_USER_SET_CONFIG   25

static int
vhost_blk_get_config(struct vhost_block_dev *bdev, uint8_t *config,
              uint32_t len)
{
    struct virtio_blk_config blkcfg;
    uint32_t blk_size;
    uint64_t blkcnt;

    if (bdev == NULL) {
        /* We can't just return -1 here as this GET_CONFIG message might
         * be caused by a QEMU VM reboot. Returning -1 will indicate an
         * error to QEMU, who might then decide to terminate itself.
         * We don't want that. A simple reboot shouldn't break the
         * system.
         *
         * Presenting a block device with block size 0 and block count 0
         * doesn't cause any problems on QEMU side and the virtio-pci
         * device is even still available inside the VM, but there will
         * be no block device created for it - the kernel drivers will
         * silently reject it.
         */
        blk_size = 0;
        blkcnt = 0;
    } else {
        blk_size = bdev->blocklen;
        blkcnt = bdev->blockcnt;
    }

    memset(&blkcfg, 0, sizeof(blkcfg));
    blkcfg.blk_size = blk_size;
    /* minimum I/O size in blocks */
    blkcfg.min_io_size = 1;
    /* expressed in 512 Bytes sectors */
    blkcfg.capacity = (blkcnt * blk_size) / 512;
    /* QEMU can overwrite this value when started */
    blkcfg.num_queues = VHOST_MAX_VQUEUES;

    fprintf(stdout, "block device:blk_size = %d, blkcnt = %"PRIx64"\n",
        blk_size, blkcnt);

    memcpy(config, &blkcfg, min(len, sizeof(blkcfg)));

    return 0;
}

static enum rte_vhost_msg_result
extern_vhost_pre_msg_handler(int vid, void *_msg)
{
    char path[PATH_MAX];
    struct vhost_blk_ctrlr *ctrlr;
    struct vhost_user_msg *msg = _msg;
    int ret;

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

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

    switch ((int)msg->request) {
    case VHOST_USER_GET_VRING_BASE:
    case VHOST_USER_SET_VRING_BASE:
    case VHOST_USER_SET_VRING_ADDR:
    case VHOST_USER_SET_VRING_NUM:
    case VHOST_USER_SET_VRING_KICK:
    case VHOST_USER_SET_VRING_CALL:
    case VHOST_USER_SET_MEM_TABLE:
        break;
    case VHOST_USER_GET_CONFIG: {
        int rc = 0;

        rc = vhost_blk_get_config(ctrlr->bdev,
                      msg->payload.cfg.region,
                      msg->payload.cfg.size);
        if (rc != 0)
            msg->size = 0;

        return RTE_VHOST_MSG_RESULT_REPLY;
    }
    case VHOST_USER_SET_CONFIG:
    default:
        break;
    }

    return RTE_VHOST_MSG_RESULT_NOT_HANDLED;
}

static enum rte_vhost_msg_result
extern_vhost_post_msg_handler(int vid, void *_msg)
{
    char path[PATH_MAX];
    struct vhost_blk_ctrlr *ctrlr;
    struct vhost_user_msg *msg = _msg;
    int ret;

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

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

    switch (msg->request) {
    case VHOST_USER_SET_FEATURES:
    case VHOST_USER_SET_VRING_KICK:
    default:
        break;
    }

    return RTE_VHOST_MSG_RESULT_NOT_HANDLED;
}

struct rte_vhost_user_extern_ops g_extern_vhost_ops = {
    .pre_msg_handle = extern_vhost_pre_msg_handler,
    .post_msg_handle = extern_vhost_post_msg_handler,
};

void
vhost_session_install_rte_compat_hooks(uint32_t vid)
{
    int rc;

    rc = rte_vhost_extern_callback_register(vid, &g_extern_vhost_ops, NULL);
    if (rc != 0)
        fprintf(stderr,
            "rte_vhost_extern_callback_register() failed for vid = %d\n",
            vid);
}

void
vhost_dev_install_rte_compat_hooks(const char *path)
{
    uint64_t protocol_features = 0;

    rte_vhost_driver_get_protocol_features(path, &protocol_features);
    protocol_features |= (1ULL << VHOST_USER_PROTOCOL_F_CONFIG);
    protocol_features |= (1ULL << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD);
    rte_vhost_driver_set_protocol_features(path, protocol_features);
}

#endif