Re: [Stratos-dev] [PATCH 3/5] vhost-user-rng: backend: Add RNG vhost-user daemon implementation

On Tue, Jun 01, 2021 at 08:03:20PM +0000, Mathieu Poirier via Stratos-dev wrote:

This patch provides the vhost-user backend implementation to work in tandem with the vhost-user-rng implementation of the QEMU VMM.

It uses the vhost-user API so that other VMM can re-use the interface without having to write the driver again.

Signed-off-by: Mathieu Poirier mathieu.poirier@linaro.org

tools/meson.build | 8 + tools/vhost-user-rng/50-qemu-rng.json.in | 5 + tools/vhost-user-rng/main.c | 403 +++++++++++++++++++++++ tools/vhost-user-rng/meson.build | 10 + 4 files changed, 426 insertions(+) create mode 100644 tools/vhost-user-rng/50-qemu-rng.json.in create mode 100644 tools/vhost-user-rng/main.c create mode 100644 tools/vhost-user-rng/meson.build

diff --git a/tools/meson.build b/tools/meson.build index 3e5a0abfa29f..66b0a11fbb45 100644 --- a/tools/meson.build +++ b/tools/meson.build @@ -24,3 +24,11 @@ endif if have_virtiofsd subdir('virtiofsd') endif

+have_virtiorng = (have_system and

• have_tools and
• 'CONFIG_LINUX' in config_host)

+if have_virtiorng

• subdir('vhost-user-rng')

+endif diff --git a/tools/vhost-user-rng/50-qemu-rng.json.in b/tools/vhost-user-rng/50-qemu-rng.json.in new file mode 100644 index 000000000000..9186c3c6fe1d --- /dev/null +++ b/tools/vhost-user-rng/50-qemu-rng.json.in @@ -0,0 +1,5 @@ +{

• "description": "QEMU vhost-user-rng",
• "type": "bridge",
• "binary": "@libexecdir@/vhost-user-rng"

+} diff --git a/tools/vhost-user-rng/main.c b/tools/vhost-user-rng/main.c new file mode 100644 index 000000000000..ba7380b12659 --- /dev/null +++ b/tools/vhost-user-rng/main.c @@ -0,0 +1,403 @@ +/*

• • VIRTIO RNG Emulation via vhost-user
• • Copyright (c) 2021 Mathieu Poirier mathieu.poirier@linaro.org
• • SPDX-License-Identifier: GPL-2.0-or-later
• */

+#define G_LOG_DOMAIN "vhost-user-rng" +#define G_LOG_USE_STRUCTURED 1

+#include <glib.h> +#include <gio/gio.h> +#include <gio/gunixsocketaddress.h> +#include <glib-unix.h> +#include <glib/gstdio.h> +#include <pthread.h> +#include <signal.h> +#include <stdio.h> +#include <stdbool.h> +#include <string.h> +#include <inttypes.h> +#include <fcntl.h> +#include <sys/ioctl.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/mman.h> +#include <time.h> +#include <unistd.h> +#include <endian.h> +#include <assert.h>

+#include "qemu/cutils.h" +#include "subprojects/libvhost-user/libvhost-user-glib.h" +#include "subprojects/libvhost-user/libvhost-user.h"

+#ifndef container_of +#define container_of(ptr, type, member) ({ \

•    const typeof(((type *) 0)->member) * __mptr = (ptr);     \
  

•    (type *) ((char *) __mptr - offsetof(type, member)); })
  

+#endif

+typedef struct {

• VugDev dev;
• struct itimerspec ts;
• timer_t rate_limit_timer;
• pthread_mutex_t rng_mutex;
• pthread_cond_t rng_cond;
• int64_t quota_remaining;
• bool activate_timer;
• GMainLoop *loop;

+} VuRNG;

+static gboolean print_cap, verbose; +static gchar *source_path, *socket_path; +static gint source_fd, socket_fd = -1;

+/* Defaults tailored on virtio-rng.c */ +static uint32_t period_ms = 1 << 16; +static uint64_t max_bytes = INT64_MAX;

+static void check_rate_limit(union sigval sv) +{

• VuRNG *rng = sv.sival_ptr;
• bool wakeup = false;
• pthread_mutex_lock(&rng->rng_mutex);
• /*

• * The timer has expired and the guest has used all available
  

• * antropy, which means function vu_rng_handle_request() is waiting
  

s/antropy/entropy/

I also found 'antropy' at two more locations in this patch (that made me wonder).

• * on us.  As such wake it up once we're done here.
  

• */
  

• if (rng->quota_remaining == 0) {

•    wakeup = true;
  

• }
• /*

• * Reset the antropy available to the guest and tell function
  

• * vu_rng_handle_requests() to start the timer before using it.
  

• */
  

• rng->quota_remaining = max_bytes;
• rng->activate_timer = true;
• pthread_mutex_unlock(&rng->rng_mutex);
• if (wakeup) {

•    pthread_cond_signal(&rng->rng_cond);
  

• }

+}

+static void setup_timer(VuRNG *rng) +{

• struct sigevent sev;
• int ret;
• memset(&rng->ts, 0, sizeof(struct itimerspec));
• rng->ts.it_value.tv_sec = period_ms / 1000;
• rng->ts.it_value.tv_nsec = (period_ms % 1000) * 1000000;
• /*

• * Call function check_rate_limit() as if it was the start of
  

• * a new thread when the timer expires.
  

• */
  

• sev.sigev_notify = SIGEV_THREAD;
• sev.sigev_notify_function = check_rate_limit;
• sev.sigev_value.sival_ptr = rng;
• /* Needs to be NULL if defaults attributes are to be used. */
• sev.sigev_notify_attributes = NULL;
• ret = timer_create(CLOCK_MONOTONIC, &sev, &rng->rate_limit_timer);
• if (ret < 0) {

•    fprintf(stderr, "timer_create() failed\n");
  

• }

+}

+/* Virtio helpers */ +static uint64_t rng_get_features(VuDev *dev) +{

• if (verbose) {

•    g_info("%s: replying", __func__);
  

• }
• return 0;

+}

+static void rng_set_features(VuDev *dev, uint64_t features) +{

• if (verbose && features) {

•    g_autoptr(GString) s = g_string_new("Requested un-handled feature");
  

•    g_string_append_printf(s, " 0x%" PRIx64 "", features);
  

•    g_info("%s: %s", __func__, s->str);
  

• }

+}

+static void vu_rng_handle_requests(VuDev *dev, int qidx) +{

• VuRNG *rng = container_of(dev, VuRNG, dev.parent);
• VuVirtq *vq = vu_get_queue(dev, qidx);
• VuVirtqElement *elem;
• size_t to_read;
• int len, ret;
• for (;;) {

•    /* Get element in the vhost virtqueue */
  

•    elem = vu_queue_pop(dev, vq, sizeof(VuVirtqElement));
  

•    if (!elem) {
  

•        break;
  

•    }
  

•    /* Get the amount of antropy to read from the vhost server */
  

•    to_read = elem->in_sg[0].iov_len;
  

•    pthread_mutex_lock(&rng->rng_mutex);
  

•    /*
  

•     * We have consumed all entropy available for this time slice.
  

•     * Wait for the timer (check_rate_limit()) to tell us about the
  

•     * start of a new time slice.
  

•     */
  

•    if (rng->quota_remaining == 0) {
  

•        pthread_cond_wait(&rng->rng_cond, &rng->rng_mutex);
  

•    }
  

•    /* Start the timer if the last time slice has expired */
  

•    if (rng->activate_timer == true) {
  

•        rng->activate_timer = false;
  

•        ret = timer_settime(rng->rate_limit_timer, 0, &rng->ts, NULL);
  

•        if (ret < 0) {
  

•            fprintf(stderr, "timer_settime() failed\n");
  

•        }
  

•    }
  

•    /* Make sure we don't read more than it's available */
  

•    if (rng->quota_remaining < to_read) {
  

•        to_read = rng->quota_remaining;
  

•    }
  

•    len = read(source_fd, elem->in_sg[0].iov_base, to_read);
  

•    /* Simply return 0 if an error occurs */
  

•    if (len < 0) {
  

•        len = 0;
  

•    }
  

•    rng->quota_remaining -= len;
  

•    pthread_mutex_unlock(&rng->rng_mutex);
  

•    vu_queue_push(dev, vq, elem, len);
  

•    free(elem);
  

• }
• vu_queue_notify(dev, vq);

+}

+static void +vu_rng_queue_set_started(VuDev *dev, int qidx, bool started) +{

• VuVirtq *vq = vu_get_queue(dev, qidx);
• g_debug("queue started %d:%d\n", qidx, started);
• if (!qidx) {

•    vu_set_queue_handler(dev, vq, started ? vu_rng_handle_requests : NULL);
  

• }

+}

+/*

• • Any messages not handled here are processed by the libvhost library
• • itself.
• */

+static int rng_process_msg(VuDev *dev, VhostUserMsg *msg, int *do_reply) +{

• VuRNG *rng = container_of(dev, VuRNG, dev.parent);
• if (msg->request == VHOST_USER_NONE) {

•    g_main_loop_quit(rng->loop);
  

•    return 1;
  

• }
• return 0;

+}

+static const VuDevIface vuiface = {

• .set_features = rng_set_features,
• .get_features = rng_get_features,
• .queue_set_started = vu_rng_queue_set_started,
• .process_msg = rng_process_msg,

+};

+static gboolean hangup(gpointer user_data) +{

• GMainLoop *loop = (GMainLoop *) user_data;
• g_printerr("%s: caught hangup/quit signal, quitting", __func__);
• g_main_loop_quit(loop);
• return true;

+}

+static void panic(VuDev *dev, const char *msg) +{

• g_critical("%s\n", msg);
• exit(EXIT_FAILURE);

+}

+/* Print vhost-user.json backend program capabilities */ +static void print_capabilities(void) +{

• printf("{\n");
• printf(" "type": "RNG"\n");
• printf(" "filename": [ RNG source ]\n");
• printf("}\n");

+}

+static GOptionEntry options[] = {

• { "socket-path", 's', 0, G_OPTION_ARG_FILENAME, &socket_path,

•  "Location of vhost-user Unix domain socket, incompatible with --fd",
  

•  "PATH" },
  

• { "fd", 'f', 0, G_OPTION_ARG_INT, &socket_fd,

•  "Specify the backend file-descriptor, incompatible with --socket-path",
  

•  "FD" },
  

• { "period", 'p', 0, G_OPTION_ARG_INT, &period_ms,

•  "Time needed (in ms) to transfer a maximum amount of byte", NULL },
  

• { "max-bytes", 'm', 0, G_OPTION_ARG_INT64, &max_bytes,

•  "Maximum amount of byte that can be transferred in a period", NULL },
  

• { "filename", 'n', 0, G_OPTION_ARG_FILENAME, &source_path,

•  "RNG source, defaults to /dev/urandom", "PATH" },
  

• { "print-capabilities", 'c', 0, G_OPTION_ARG_NONE, &print_cap,

•  "Output to stdout the backend capabilities in JSON format and exit",
  

•  NULL},
  

• { "verbose", 'v', 0, G_OPTION_ARG_NONE, &verbose,

•  "Be more verbose in output", NULL},
  

• { NULL }

+};

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

• GError *error = NULL;
• GOptionContext *context;
• g_autoptr(GSocket) socket = NULL;
• char default_source[] = "/dev/urandom";
• char *source = default_source;
• VuRNG rng;
• context = g_option_context_new("vhost-user emulation of RNG device");
• g_option_context_add_main_entries(context, options, "vhost-user-rng");
• if (!g_option_context_parse(context, &argc, &argv, &error)) {

•    g_printerr("option parsing failed: %s\n", error->message);
  

•    exit(1);
  

• }
• if (print_cap) {

•    print_capabilities();
  

•    exit(0);
  

• }
• if (!socket_path && socket_fd < 0) {

•    g_printerr("Please specify either --fd or --socket-path\n");
  

•    exit(EXIT_FAILURE);
  

• }
• if (socket_path && socket_fd > 0) {

•    g_printerr("Either --fd or --socket-path, not both\n");
  

•    exit(EXIT_FAILURE);
  

• }
• if (max_bytes > INT64_MAX) {

•    g_printerr("'max-bytes' parameter must be non-negative, "
  

•               "and less than 2^63\n");
  

•    exit(EXIT_FAILURE);
  

• }
• if (period_ms <= 0) {

•    g_printerr("'period' parameter expects a positive integer\n");
  

•    exit(EXIT_FAILURE);
  

• }
• /*

• * Now create a vhost-user socket that we will receive messages
  

• * on. Once we have our handler set up we can enter the glib main
  

• * loop.
  

• */
  

• if (socket_path) {

•    g_autoptr(GSocketAddress) addr = g_unix_socket_address_new(socket_path);
  

•    g_autoptr(GSocket) bind_socket = g_socket_new(G_SOCKET_FAMILY_UNIX,
  

•                                                  G_SOCKET_TYPE_STREAM,
  

•                                                  G_SOCKET_PROTOCOL_DEFAULT,
  

•                                                  &error);
  

•    if (!g_socket_bind(bind_socket, addr, false, &error)) {
  

•        g_printerr("Failed to bind to socket at %s (%s).\n",
  

•                   socket_path, error->message);
  

•        exit(EXIT_FAILURE);
  

•    }
  

•    if (!g_socket_listen(bind_socket, &error)) {
  

•        g_printerr("Failed to listen on socket %s (%s).\n",
  

•                   socket_path, error->message);
  

•    }
  

•    g_message("awaiting connection to %s", socket_path);
  

•    socket = g_socket_accept(bind_socket, NULL, &error);
  

•    if (!socket) {
  

•        g_printerr("Failed to accept on socket %s (%s).\n",
  

•                   socket_path, error->message);
  

•    }
  

• } else {

•    socket = g_socket_new_from_fd(socket_fd, &error);
  

•    if (!socket) {
  

•        g_printerr("Failed to connect to FD %d (%s).\n",
  

•                   socket_fd, error->message);
  

•        exit(EXIT_FAILURE);
  

•    }
  

• }
• /* Overwrite default RNG source with what user provided, if any */
• if (source_path) {

•    source = source_path;
  

• }
• source_fd = open(source, O_RDWR);
• if (source_fd < 0) {

•    g_printerr("Failed to open RNG source %s\n", source);
  

•    g_socket_close(socket, &error);
  

•    unlink(socket_path);
  

•    exit(EXIT_FAILURE);
  

• }
• /* catch exit signals */
• g_unix_signal_add(SIGHUP, hangup, rng.loop);
• g_unix_signal_add(SIGINT, hangup, rng.loop);
• /*

• * Create the main loop first so all the various sources can be
  

• * added. As well as catching signals we need to ensure vug_init
  

• * can add it's GSource watches.
  

• */
  

• rng.loop = g_main_loop_new(NULL, FALSE);
• if (!vug_init(&rng.dev, 1, g_socket_get_fd(socket),

•              panic, &vuiface)) {
  

•    g_printerr("Failed to initialize libvhost-user-glib.\n");
  

•    exit(EXIT_FAILURE);
  

• }
• rng.quota_remaining = max_bytes;
• rng.activate_timer = true;
• pthread_mutex_init(&rng.rng_mutex, NULL);
• pthread_cond_init(&rng.rng_cond, NULL);
• setup_timer(&rng);
• if (verbose) {

•    g_info("period_ms: %d tv_sec: %ld tv_nsec: %lu\n",
  

•           period_ms, rng.ts.it_value.tv_sec, rng.ts.it_value.tv_nsec);
  

• }
• g_message("entering main loop, awaiting messages");
• g_main_loop_run(rng.loop);
• g_message("finished main loop, cleaning up");
• g_main_loop_unref(rng.loop);
• vug_deinit(&rng.dev);
• timer_delete(rng.rate_limit_timer);
• close(source_fd);
• unlink(socket_path);

+} diff --git a/tools/vhost-user-rng/meson.build b/tools/vhost-user-rng/meson.build new file mode 100644 index 000000000000..4dc386daf335 --- /dev/null +++ b/tools/vhost-user-rng/meson.build @@ -0,0 +1,10 @@ +executable('vhost-user-rng', files(

• 'main.c'),
• dependencies: [qemuutil, glib, gio, rt],
• install: true,
• install_dir: get_option('libexecdir'))

+configure_file(input: '50-qemu-rng.json.in',

•           output: '50-qemu-rng.json',
  

•           configuration: config_host,
  

•           install_dir: qemu_datadir / 'vhost-user')
  

-- 2.25.1

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