contrib/vhost-user-blk: introduce a vhost-user-blk sample application

This commit introduces a vhost-user-blk backend device, it uses UNIX
domain socket to communicate with QEMU. The vhost-user-blk sample
application should be used with QEMU vhost-user-blk-pci device.

To use it, complie with:
make vhost-user-blk

and start like this:
vhost-user-blk -b /dev/sdb -s /path/vhost.socket

Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 546 insertions, 0 deletions

diff --git a/contrib/vhost-user-blk/Makefile.objs b/contrib/vhost-user-blk/Makefile.objs
new file mode 100644
index 0000000..72e2cdc
--- /dev/null
+++ b/contrib/vhost-user-blk/Makefile.objs
@@ -0,0 +1 @@
+vhost-user-blk-obj-y = vhost-user-blk.o
diff --git a/contrib/vhost-user-blk/vhost-user-blk.c b/contrib/vhost-user-blk/vhost-user-blk.c
new file mode 100644
index 0000000..67dac81
--- /dev/null
+++ b/contrib/vhost-user-blk/vhost-user-blk.c
@@ -0,0 +1,545 @@
+/*
+ * vhost-user-blk sample application
+ *
+ * Copyright (c) 2017 Intel Corporation. All rights reserved.
+ *
+ * Author:
+ *  Changpeng Liu <changpeng.liu@intel.com>
+ *
+ * This work is based on the "vhost-user-scsi" sample and "virtio-blk" driver
+ * implementation by:
+ *  Felipe Franciosi <felipe@nutanix.com>
+ *  Anthony Liguori <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 only.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "standard-headers/linux/virtio_blk.h"
+#include "contrib/libvhost-user/libvhost-user-glib.h"
+#include "contrib/libvhost-user/libvhost-user.h"
+
+#include <glib.h>
+
+struct virtio_blk_inhdr {
+    unsigned char status;
+};
+
+/* vhost user block device */
+typedef struct VubDev {
+    VugDev parent;
+    int blk_fd;
+    struct virtio_blk_config blkcfg;
+    char *blk_name;
+    GMainLoop *loop;
+} VubDev;
+
+typedef struct VubReq {
+    VuVirtqElement *elem;
+    int64_t sector_num;
+    size_t size;
+    struct virtio_blk_inhdr *in;
+    struct virtio_blk_outhdr *out;
+    VubDev *vdev_blk;
+    struct VuVirtq *vq;
+} VubReq;
+
+/* refer util/iov.c */
+static size_t vub_iov_size(const struct iovec *iov,
+                              const unsigned int iov_cnt)
+{
+    size_t len;
+    unsigned int i;
+
+    len = 0;
+    for (i = 0; i < iov_cnt; i++) {
+        len += iov[i].iov_len;
+    }
+    return len;
+}
+
+static void vub_panic_cb(VuDev *vu_dev, const char *buf)
+{
+    VugDev *gdev;
+    VubDev *vdev_blk;
+
+    assert(vu_dev);
+
+    gdev = container_of(vu_dev, VugDev, parent);
+    vdev_blk = container_of(gdev, VubDev, parent);
+    if (buf) {
+        g_warning("vu_panic: %s", buf);
+    }
+
+    g_main_loop_quit(vdev_blk->loop);
+}
+
+static void vub_req_complete(VubReq *req)
+{
+    VugDev *gdev = &req->vdev_blk->parent;
+    VuDev *vu_dev = &gdev->parent;
+
+    /* IO size with 1 extra status byte */
+    vu_queue_push(vu_dev, req->vq, req->elem,
+                  req->size + 1);
+    vu_queue_notify(vu_dev, req->vq);
+
+    if (req->elem) {
+        free(req->elem);
+    }
+
+    g_free(req);
+}
+
+static int vub_open(const char *file_name, bool wce)
+{
+    int fd;
+    int flags = O_RDWR;
+
+    if (!wce) {
+        flags |= O_DIRECT;
+    }
+
+    fd = open(file_name, flags);
+    if (fd < 0) {
+        fprintf(stderr, "Cannot open file %s, %s\n", file_name,
+                strerror(errno));
+        return -1;
+    }
+
+    return fd;
+}
+
+static ssize_t
+vub_readv(VubReq *req, struct iovec *iov, uint32_t iovcnt)
+{
+    VubDev *vdev_blk = req->vdev_blk;
+    ssize_t rc;
+
+    if (!iovcnt) {
+        fprintf(stderr, "Invalid Read IOV count\n");
+        return -1;
+    }
+
+    req->size = vub_iov_size(iov, iovcnt);
+    rc = preadv(vdev_blk->blk_fd, iov, iovcnt, req->sector_num * 512);
+    if (rc < 0) {
+        fprintf(stderr, "%s, Sector %"PRIu64", Size %lu failed with %s\n",
+                vdev_blk->blk_name, req->sector_num, req->size,
+                strerror(errno));
+        return -1;
+    }
+
+    return rc;
+}
+
+static ssize_t
+vub_writev(VubReq *req, struct iovec *iov, uint32_t iovcnt)
+{
+    VubDev *vdev_blk = req->vdev_blk;
+    ssize_t rc;
+
+    if (!iovcnt) {
+        fprintf(stderr, "Invalid Write IOV count\n");
+        return -1;
+    }
+
+    req->size = vub_iov_size(iov, iovcnt);
+    rc = pwritev(vdev_blk->blk_fd, iov, iovcnt, req->sector_num * 512);
+    if (rc < 0) {
+        fprintf(stderr, "%s, Sector %"PRIu64", Size %lu failed with %s\n",
+                vdev_blk->blk_name, req->sector_num, req->size,
+                strerror(errno));
+        return -1;
+    }
+
+    return rc;
+}
+
+static void
+vub_flush(VubReq *req)
+{
+    VubDev *vdev_blk = req->vdev_blk;
+
+    fdatasync(vdev_blk->blk_fd);
+}
+
+static int vub_virtio_process_req(VubDev *vdev_blk,
+                                     VuVirtq *vq)
+{
+    VugDev *gdev = &vdev_blk->parent;
+    VuDev *vu_dev = &gdev->parent;
+    VuVirtqElement *elem;
+    uint32_t type;
+    unsigned in_num;
+    unsigned out_num;
+    VubReq *req;
+
+    elem = vu_queue_pop(vu_dev, vq, sizeof(VuVirtqElement) + sizeof(VubReq));
+    if (!elem) {
+        return -1;
+    }
+
+    /* refer to hw/block/virtio_blk.c */
+    if (elem->out_num < 1 || elem->in_num < 1) {
+        fprintf(stderr, "virtio-blk request missing headers\n");
+        free(elem);
+        return -1;
+    }
+
+    req = g_new0(VubReq, 1);
+    req->vdev_blk = vdev_blk;
+    req->vq = vq;
+    req->elem = elem;
+
+    in_num = elem->in_num;
+    out_num = elem->out_num;
+
+    /* don't support VIRTIO_F_ANY_LAYOUT and virtio 1.0 only */
+    if (elem->out_sg[0].iov_len < sizeof(struct virtio_blk_outhdr)) {
+        fprintf(stderr, "Invalid outhdr size\n");
+        goto err;
+    }
+    req->out = (struct virtio_blk_outhdr *)elem->out_sg[0].iov_base;
+    out_num--;
+
+    if (elem->in_sg[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) {
+        fprintf(stderr, "Invalid inhdr size\n");
+        goto err;
+    }
+    req->in = (struct virtio_blk_inhdr *)elem->in_sg[in_num - 1].iov_base;
+    in_num--;
+
+    type = le32toh(req->out->type);
+    switch (type & ~(VIRTIO_BLK_T_OUT | VIRTIO_BLK_T_BARRIER)) {
+        case VIRTIO_BLK_T_IN: {
+            ssize_t ret = 0;
+            bool is_write = type & VIRTIO_BLK_T_OUT;
+            req->sector_num = le64toh(req->out->sector);
+            if (is_write) {
+                ret  = vub_writev(req, &elem->out_sg[1], out_num);
+            } else {
+                ret = vub_readv(req, &elem->in_sg[0], in_num);
+            }
+            if (ret >= 0) {
+                req->in->status = VIRTIO_BLK_S_OK;
+            } else {
+                req->in->status = VIRTIO_BLK_S_IOERR;
+            }
+            vub_req_complete(req);
+            break;
+        }
+        case VIRTIO_BLK_T_FLUSH: {
+            vub_flush(req);
+            req->in->status = VIRTIO_BLK_S_OK;
+            vub_req_complete(req);
+            break;
+        }
+        case VIRTIO_BLK_T_GET_ID: {
+            size_t size = MIN(vub_iov_size(&elem->in_sg[0], in_num),
+                              VIRTIO_BLK_ID_BYTES);
+            snprintf(elem->in_sg[0].iov_base, size, "%s", "vhost_user_blk");
+            req->in->status = VIRTIO_BLK_S_OK;
+            req->size = elem->in_sg[0].iov_len;
+            vub_req_complete(req);
+            break;
+        }
+        default: {
+            req->in->status = VIRTIO_BLK_S_UNSUPP;
+            vub_req_complete(req);
+            break;
+        }
+    }
+
+    return 0;
+
+err:
+    free(elem);
+    g_free(req);
+    return -1;
+}
+
+static void vub_process_vq(VuDev *vu_dev, int idx)
+{
+    VugDev *gdev;
+    VubDev *vdev_blk;
+    VuVirtq *vq;
+    int ret;
+
+    if ((idx < 0) || (idx >= VHOST_MAX_NR_VIRTQUEUE)) {
+        fprintf(stderr, "VQ Index out of range: %d\n", idx);
+        vub_panic_cb(vu_dev, NULL);
+        return;
+    }
+
+    gdev = container_of(vu_dev, VugDev, parent);
+    vdev_blk = container_of(gdev, VubDev, parent);
+    assert(vdev_blk);
+
+    vq = vu_get_queue(vu_dev, idx);
+    assert(vq);
+
+    while (1) {
+        ret = vub_virtio_process_req(vdev_blk, vq);
+        if (ret) {
+            break;
+        }
+    }
+}
+
+static void vub_queue_set_started(VuDev *vu_dev, int idx, bool started)
+{
+    VuVirtq *vq;
+
+    assert(vu_dev);
+
+    vq = vu_get_queue(vu_dev, idx);
+    vu_set_queue_handler(vu_dev, vq, started ? vub_process_vq : NULL);
+}
+
+static uint64_t
+vub_get_features(VuDev *dev)
+{
+    return 1ull << VIRTIO_BLK_F_SIZE_MAX |
+           1ull << VIRTIO_BLK_F_SEG_MAX |
+           1ull << VIRTIO_BLK_F_TOPOLOGY |
+           1ull << VIRTIO_BLK_F_BLK_SIZE |
+           1ull << VIRTIO_BLK_F_FLUSH |
+           1ull << VIRTIO_BLK_F_CONFIG_WCE |
+           1ull << VIRTIO_F_VERSION_1 |
+           1ull << VHOST_USER_F_PROTOCOL_FEATURES;
+}
+
+static int
+vub_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
+{
+    VugDev *gdev;
+    VubDev *vdev_blk;
+
+    gdev = container_of(vu_dev, VugDev, parent);
+    vdev_blk = container_of(gdev, VubDev, parent);
+    memcpy(config, &vdev_blk->blkcfg, len);
+
+    return 0;
+}
+
+static int
+vub_set_config(VuDev *vu_dev, const uint8_t *data,
+               uint32_t offset, uint32_t size, uint32_t flags)
+{
+    VugDev *gdev;
+    VubDev *vdev_blk;
+    uint8_t wce;
+    int fd;
+
+    /* don't support live migration */
+    if (flags != VHOST_SET_CONFIG_TYPE_MASTER) {
+        return -1;
+    }
+
+    gdev = container_of(vu_dev, VugDev, parent);
+    vdev_blk = container_of(gdev, VubDev, parent);
+
+    if (offset != offsetof(struct virtio_blk_config, wce) ||
+        size != 1) {
+        return -1;
+    }
+
+    wce = *data;
+    if (wce == vdev_blk->blkcfg.wce) {
+        /* Do nothing as same with old configuration */
+        return 0;
+    }
+
+    vdev_blk->blkcfg.wce = wce;
+    fprintf(stdout, "Write Cache Policy Changed\n");
+    if (vdev_blk->blk_fd >= 0) {
+        close(vdev_blk->blk_fd);
+        vdev_blk->blk_fd = -1;
+    }
+
+    fd = vub_open(vdev_blk->blk_name, wce);
+    if (fd < 0) {
+        fprintf(stderr, "Error to open block device %s\n", vdev_blk->blk_name);
+        vdev_blk->blk_fd = -1;
+        return -1;
+    }
+    vdev_blk->blk_fd = fd;
+
+    return 0;
+}
+
+static const VuDevIface vub_iface = {
+    .get_features = vub_get_features,
+    .queue_set_started = vub_queue_set_started,
+    .get_config = vub_get_config,
+    .set_config = vub_set_config,
+};
+
+static int unix_sock_new(char *unix_fn)
+{
+    int sock;
+    struct sockaddr_un un;
+    size_t len;
+
+    assert(unix_fn);
+
+    sock = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (sock <= 0) {
+        perror("socket");
+        return -1;
+    }
+
+    un.sun_family = AF_UNIX;
+    (void)snprintf(un.sun_path, sizeof(un.sun_path), "%s", unix_fn);
+    len = sizeof(un.sun_family) + strlen(un.sun_path);
+
+    (void)unlink(unix_fn);
+    if (bind(sock, (struct sockaddr *)&un, len) < 0) {
+        perror("bind");
+        goto fail;
+    }
+
+    if (listen(sock, 1) < 0) {
+        perror("listen");
+        goto fail;
+    }
+
+    return sock;
+
+fail:
+    (void)close(sock);
+
+    return -1;
+}
+
+static void vub_free(struct VubDev *vdev_blk)
+{
+    if (!vdev_blk) {
+        return;
+    }
+
+    g_main_loop_unref(vdev_blk->loop);
+    if (vdev_blk->blk_fd >= 0) {
+        close(vdev_blk->blk_fd);
+    }
+    g_free(vdev_blk);
+}
+
+static uint32_t
+vub_get_blocksize(int fd)
+{
+    uint32_t blocksize = 512;
+
+#if defined(__linux__) && defined(BLKSSZGET)
+    if (ioctl(fd, BLKSSZGET, &blocksize) == 0) {
+        return blocklen;
+    }
+#endif
+
+    return blocksize;
+}
+
+static void
+vub_initialize_config(int fd, struct virtio_blk_config *config)
+{
+    off64_t capacity;
+
+    capacity = lseek64(fd, 0, SEEK_END);
+    config->capacity = capacity >> 9;
+    config->blk_size = vub_get_blocksize(fd);
+    config->size_max = 65536;
+    config->seg_max = 128 - 2;
+    config->min_io_size = 1;
+    config->opt_io_size = 1;
+    config->num_queues = 1;
+}
+
+static VubDev *
+vub_new(char *blk_file)
+{
+    VubDev *vdev_blk;
+
+    vdev_blk = g_new0(VubDev, 1);
+    vdev_blk->loop = g_main_loop_new(NULL, FALSE);
+    vdev_blk->blk_fd = vub_open(blk_file, 0);
+    if (vdev_blk->blk_fd  < 0) {
+        fprintf(stderr, "Error to open block device %s\n", blk_file);
+        vub_free(vdev_blk);
+        return NULL;
+    }
+    vdev_blk->blkcfg.wce = 0;
+    vdev_blk->blk_name = blk_file;
+
+    /* fill virtio_blk_config with block parameters */
+    vub_initialize_config(vdev_blk->blk_fd, &vdev_blk->blkcfg);
+
+    return vdev_blk;
+}
+
+int main(int argc, char **argv)
+{
+    int opt;
+    char *unix_socket = NULL;
+    char *blk_file = NULL;
+    int lsock = -1, csock = -1;
+    VubDev *vdev_blk = NULL;
+
+    while ((opt = getopt(argc, argv, "b:s:h")) != -1) {
+        switch (opt) {
+        case 'b':
+            blk_file = g_strdup(optarg);
+            break;
+        case 's':
+            unix_socket = g_strdup(optarg);
+            break;
+        case 'h':
+        default:
+            printf("Usage: %s [-b block device or file, -s UNIX domain socket]"
+                   " | [ -h ]\n", argv[0]);
+            return 0;
+        }
+    }
+
+    if (!unix_socket || !blk_file) {
+        printf("Usage: %s [-b block device or file, -s UNIX domain socket] |"
+               " [ -h ]\n", argv[0]);
+        return -1;
+    }
+
+    lsock = unix_sock_new(unix_socket);
+    if (lsock < 0) {
+        goto err;
+    }
+
+    csock = accept(lsock, (void *)0, (void *)0);
+    if (csock < 0) {
+        fprintf(stderr, "Accept error %s\n", strerror(errno));
+        goto err;
+    }
+
+    vdev_blk = vub_new(blk_file);
+    if (!vdev_blk) {
+        goto err;
+    }
+
+    vug_init(&vdev_blk->parent, csock, vub_panic_cb, &vub_iface);
+
+    g_main_loop_run(vdev_blk->loop);
+
+    vug_deinit(&vdev_blk->parent);
+
+err:
+    vub_free(vdev_blk);
+    if (csock >= 0) {
+        close(csock);
+    }
+    if (lsock >= 0) {
+        close(lsock);
+    }
+    g_free(unix_socket);
+    g_free(blk_file);
+
+    return 0;
+}