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 + * 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')