contrib: add vhost-user-input

Add a vhost-user input backend example, based on virtio-input-host
device. It takes an evdev path as argument, and can be associated with
a vhost-user-input device via a UNIX socket:

$ vhost-user-input -p /dev/input/eventX -s /tmp/vui.sock

$ qemu ... -chardev socket,id=vuic,path=/tmp/vui.sock
  -device vhost-user-input-pci,chardev=vuic

This example is intentionally not included in $TOOLS, and not
installed by default.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20190514104126.6294-4-marcandre.lureau@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

2 files changed, 394 insertions, 0 deletions

diff --git a/contrib/vhost-user-input/Makefile.objs b/contrib/vhost-user-input/Makefile.objs
new file mode 100644
index 0000000..b1fad90
--- /dev/null
+++ b/contrib/vhost-user-input/Makefile.objs
@@ -0,0 +1 @@
+vhost-user-input-obj-y = main.o
diff --git a/contrib/vhost-user-input/main.c b/contrib/vhost-user-input/main.c
new file mode 100644
index 0000000..8d493f5
--- /dev/null
+++ b/contrib/vhost-user-input/main.c
@@ -0,0 +1,393 @@
+/*
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * (at your option) any later version.  See the COPYING file in the
+ * top-level directory.
+ */
+
+#include "qemu/osdep.h"
+
+#include <glib.h>
+#include <linux/input.h>
+
+#include "qemu/iov.h"
+#include "qemu/bswap.h"
+#include "qemu/sockets.h"
+#include "contrib/libvhost-user/libvhost-user.h"
+#include "contrib/libvhost-user/libvhost-user-glib.h"
+#include "standard-headers/linux/virtio_input.h"
+#include "qapi/error.h"
+
+typedef struct virtio_input_event virtio_input_event;
+typedef struct virtio_input_config virtio_input_config;
+
+typedef struct VuInput {
+    VugDev dev;
+    GSource *evsrc;
+    int evdevfd;
+    GArray *config;
+    virtio_input_config *sel_config;
+    struct {
+        virtio_input_event event;
+        VuVirtqElement *elem;
+    } *queue;
+    uint32_t qindex, qsize;
+} VuInput;
+
+static void vi_input_send(VuInput *vi, struct virtio_input_event *event)
+{
+    VuDev *dev = &vi->dev.parent;
+    VuVirtq *vq = vu_get_queue(dev, 0);
+    VuVirtqElement *elem;
+    int i, len;
+
+    /* queue up events ... */
+    if (vi->qindex == vi->qsize) {
+        vi->qsize++;
+        vi->queue = g_realloc_n(vi->queue, vi->qsize, sizeof(vi->queue[0]));
+    }
+    vi->queue[vi->qindex++].event = *event;
+
+    /* ... until we see a report sync ... */
+    if (event->type != htole16(EV_SYN) ||
+        event->code != htole16(SYN_REPORT)) {
+        return;
+    }
+
+    /* ... then check available space ... */
+    for (i = 0; i < vi->qindex; i++) {
+        elem = vu_queue_pop(dev, vq, sizeof(VuVirtqElement));
+        if (!elem) {
+            while (--i >= 0) {
+                vu_queue_unpop(dev, vq, vi->queue[i].elem, 0);
+            }
+            vi->qindex = 0;
+            g_warning("virtio-input queue full");
+            return;
+        }
+        vi->queue[i].elem = elem;
+    }
+
+    /* ... and finally pass them to the guest */
+    for (i = 0; i < vi->qindex; i++) {
+        elem = vi->queue[i].elem;
+        len = iov_from_buf(elem->in_sg, elem->in_num,
+                           0, &vi->queue[i].event, sizeof(virtio_input_event));
+        vu_queue_push(dev, vq, elem, len);
+        g_free(elem);
+    }
+
+    vu_queue_notify(&vi->dev.parent, vq);
+    vi->qindex = 0;
+}
+
+static void
+vi_evdev_watch(VuDev *dev, int condition, void *data)
+{
+    VuInput *vi = data;
+    int fd = vi->evdevfd;
+
+    g_debug("Got evdev condition %x", condition);
+
+    struct virtio_input_event virtio;
+    struct input_event evdev;
+    int rc;
+
+    for (;;) {
+        rc = read(fd, &evdev, sizeof(evdev));
+        if (rc != sizeof(evdev)) {
+            break;
+        }
+
+        g_debug("input %d %d %d", evdev.type, evdev.code, evdev.value);
+
+        virtio.type  = htole16(evdev.type);
+        virtio.code  = htole16(evdev.code);
+        virtio.value = htole32(evdev.value);
+        vi_input_send(vi, &virtio);
+    }
+}
+
+
+static void vi_handle_status(VuInput *vi, virtio_input_event *event)
+{
+    struct input_event evdev;
+    int rc;
+
+    if (gettimeofday(&evdev.time, NULL)) {
+        perror("vi_handle_status: gettimeofday");
+        return;
+    }
+
+    evdev.type = le16toh(event->type);
+    evdev.code = le16toh(event->code);
+    evdev.value = le32toh(event->value);
+
+    rc = write(vi->evdevfd, &evdev, sizeof(evdev));
+    if (rc == -1) {
+        perror("vi_host_handle_status: write");
+    }
+}
+
+static void vi_handle_sts(VuDev *dev, int qidx)
+{
+    VuInput *vi = container_of(dev, VuInput, dev.parent);
+    VuVirtq *vq = vu_get_queue(dev, qidx);
+    virtio_input_event event;
+    VuVirtqElement *elem;
+    int len;
+
+    g_debug("%s", G_STRFUNC);
+
+    for (;;) {
+        elem = vu_queue_pop(dev, vq, sizeof(VuVirtqElement));
+        if (!elem) {
+            break;
+        }
+
+        memset(&event, 0, sizeof(event));
+        len = iov_to_buf(elem->out_sg, elem->out_num,
+                         0, &event, sizeof(event));
+        vi_handle_status(vi, &event);
+        vu_queue_push(dev, vq, elem, len);
+        g_free(elem);
+    }
+
+    vu_queue_notify(&vi->dev.parent, vq);
+}
+
+static void
+vi_panic(VuDev *dev, const char *msg)
+{
+    g_critical("%s\n", msg);
+    exit(EXIT_FAILURE);
+}
+
+static void
+vi_queue_set_started(VuDev *dev, int qidx, bool started)
+{
+    VuInput *vi = container_of(dev, VuInput, dev.parent);
+    VuVirtq *vq = vu_get_queue(dev, qidx);
+
+    g_debug("queue started %d:%d", qidx, started);
+
+    if (qidx == 1) {
+        vu_set_queue_handler(dev, vq, started ? vi_handle_sts : NULL);
+    }
+
+    started = vu_queue_started(dev, vu_get_queue(dev, 0)) &&
+        vu_queue_started(dev, vu_get_queue(dev, 1));
+
+    if (started && !vi->evsrc) {
+        vi->evsrc = vug_source_new(&vi->dev, vi->evdevfd,
+                                   G_IO_IN, vi_evdev_watch, vi);
+    }
+
+    if (!started && vi->evsrc) {
+        g_source_destroy(vi->evsrc);
+        vi->evsrc = NULL;
+    }
+}
+
+static virtio_input_config *
+vi_find_config(VuInput *vi, uint8_t select, uint8_t subsel)
+{
+    virtio_input_config *cfg;
+    int i;
+
+    for (i = 0; i < vi->config->len; i++) {
+        cfg = &g_array_index(vi->config, virtio_input_config, i);
+        if (select == cfg->select && subsel == cfg->subsel) {
+            return cfg;
+        }
+    }
+
+    return NULL;
+}
+
+static int vi_get_config(VuDev *dev, uint8_t *config, uint32_t len)
+{
+    VuInput *vi = container_of(dev, VuInput, dev.parent);
+
+    g_return_val_if_fail(len <= sizeof(*vi->sel_config), -1);
+
+    if (vi->sel_config) {
+        memcpy(config, vi->sel_config, len);
+    } else {
+        memset(config, 0, len);
+    }
+
+    return 0;
+}
+
+static int vi_set_config(VuDev *dev, const uint8_t *data,
+                         uint32_t offset, uint32_t size,
+                         uint32_t flags)
+{
+    VuInput *vi = container_of(dev, VuInput, dev.parent);
+    virtio_input_config *config = (virtio_input_config *)data;
+
+    vi->sel_config = vi_find_config(vi, config->select, config->subsel);
+
+    return 0;
+}
+
+static const VuDevIface vuiface = {
+    .queue_set_started = vi_queue_set_started,
+    .get_config = vi_get_config,
+    .set_config = vi_set_config,
+};
+
+static void
+vi_bits_config(VuInput *vi, int type, int count)
+{
+    virtio_input_config bits;
+    int rc, i, size = 0;
+
+    memset(&bits, 0, sizeof(bits));
+    rc = ioctl(vi->evdevfd, EVIOCGBIT(type, count / 8), bits.u.bitmap);
+    if (rc < 0) {
+        return;
+    }
+
+    for (i = 0; i < count / 8; i++) {
+        if (bits.u.bitmap[i]) {
+            size = i + 1;
+        }
+    }
+    if (size == 0) {
+        return;
+    }
+
+    bits.select = VIRTIO_INPUT_CFG_EV_BITS;
+    bits.subsel = type;
+    bits.size   = size;
+    g_array_append_val(vi->config, bits);
+}
+
+static char *opt_evdev;
+static int opt_fdnum = -1;
+static char *opt_socket_path;
+static gboolean opt_nograb;
+static gboolean opt_print_caps;
+
+static GOptionEntry entries[] = {
+    { "print-capabilities", 'c', 0, G_OPTION_ARG_NONE, &opt_print_caps,
+      "Print capabilities", NULL },
+    { "no-grab", 'n', 0, G_OPTION_ARG_NONE, &opt_nograb,
+      "Don't grab device", NULL },
+    { "fd", 'f', 0, G_OPTION_ARG_INT, &opt_fdnum,
+      "Use inherited fd socket", "FDNUM" },
+    { "socket-path", 's', 0, G_OPTION_ARG_FILENAME, &opt_socket_path,
+      "Use UNIX socket path", "PATH" },
+    { "evdev-path", 'p', 0, G_OPTION_ARG_FILENAME, &opt_evdev,
+      "evdev input device path", "PATH" },
+    { NULL, }
+};
+
+int
+main(int argc, char *argv[])
+{
+    GMainLoop *loop = NULL;
+    VuInput vi = { 0, };
+    int rc, ver, fd;
+    virtio_input_config id;
+    struct input_id ids;
+    GError *error = NULL;
+    GOptionContext *context;
+
+    context = g_option_context_new(NULL);
+    g_option_context_add_main_entries(context, entries, NULL);
+    if (!g_option_context_parse(context, &argc, &argv, &error)) {
+        g_printerr("Option parsing failed: %s\n", error->message);
+        exit(EXIT_FAILURE);
+    }
+    if (opt_print_caps) {
+        g_print("{\n");
+        g_print("  \"type\": \"input\",\n");
+        g_print("  \"features\": [\n");
+        g_print("    \"evdev-path\",\n");
+        g_print("    \"no-grab\"\n");
+        g_print("  ]\n");
+        g_print("}\n");
+        exit(EXIT_SUCCESS);
+    }
+    if (!opt_evdev) {
+        g_printerr("Please specify an evdev path\n");
+        exit(EXIT_FAILURE);
+    }
+    if ((!!opt_socket_path + (opt_fdnum != -1)) != 1) {
+        g_printerr("Please specify either --fd or --socket-path\n");
+        exit(EXIT_FAILURE);
+    }
+
+    vi.evdevfd = open(opt_evdev, O_RDWR);
+    if (vi.evdevfd < 0) {
+        g_printerr("Failed to open evdev: %s\n", g_strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+
+    rc = ioctl(vi.evdevfd, EVIOCGVERSION, &ver);
+    if (rc < 0) {
+        g_printerr("%s: is not an evdev device\n", argv[1]);
+        exit(EXIT_FAILURE);
+    }
+
+    if (!opt_nograb) {
+        rc = ioctl(vi.evdevfd, EVIOCGRAB, 1);
+        if (rc < 0) {
+            g_printerr("Failed to grab device\n");
+            exit(EXIT_FAILURE);
+        }
+    }
+
+    vi.config = g_array_new(false, false, sizeof(virtio_input_config));
+    memset(&id, 0, sizeof(id));
+    ioctl(vi.evdevfd, EVIOCGNAME(sizeof(id.u.string) - 1), id.u.string);
+    id.select = VIRTIO_INPUT_CFG_ID_NAME;
+    id.size = strlen(id.u.string);
+    g_array_append_val(vi.config, id);
+
+    if (ioctl(vi.evdevfd, EVIOCGID, &ids) == 0) {
+        memset(&id, 0, sizeof(id));
+        id.select = VIRTIO_INPUT_CFG_ID_DEVIDS;
+        id.size = sizeof(struct virtio_input_devids);
+        id.u.ids.bustype = cpu_to_le16(ids.bustype);
+        id.u.ids.vendor  = cpu_to_le16(ids.vendor);
+        id.u.ids.product = cpu_to_le16(ids.product);
+        id.u.ids.version = cpu_to_le16(ids.version);
+        g_array_append_val(vi.config, id);
+    }
+
+    vi_bits_config(&vi, EV_KEY, KEY_CNT);
+    vi_bits_config(&vi, EV_REL, REL_CNT);
+    vi_bits_config(&vi, EV_ABS, ABS_CNT);
+    vi_bits_config(&vi, EV_MSC, MSC_CNT);
+    vi_bits_config(&vi, EV_SW,  SW_CNT);
+    g_debug("config length: %u", vi.config->len);
+
+    if (opt_socket_path) {
+        int lsock = unix_listen(opt_socket_path, &error_fatal);
+        fd = accept(lsock, NULL, NULL);
+        close(lsock);
+    } else {
+        fd = opt_fdnum;
+    }
+    if (fd == -1) {
+        g_printerr("Invalid socket");
+        exit(EXIT_FAILURE);
+    }
+    vug_init(&vi.dev, fd, vi_panic, &vuiface);
+
+    loop = g_main_loop_new(NULL, FALSE);
+    g_main_loop_run(loop);
+    g_main_loop_unref(loop);
+
+    vug_deinit(&vi.dev);
+
+    if (vi.evsrc) {
+        g_source_unref(vi.evsrc);
+    }
+    g_array_free(vi.config, TRUE);
+    g_free(vi.queue);
+    return 0;
+}