tools: Add guest trace agent as a user tool

This patch adds a user tool, "trace agent" for sending trace data of a guest to
a Host in low overhead. This agent has the following functions:
 - splice a page of ring-buffer to read_pipe without memory copying
 - splice the page from write_pipe to virtio-console without memory copying
 - write trace data to stdout by using -o option
 - controlled by start/stop orders from a Host

Changes in v2:
 - Cleanup (change fprintf() to pr_err() and an include guard)

Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

6 files changed, 806 insertions, 0 deletions

diff --git a/tools/virtio/virtio-trace/Makefile b/tools/virtio/virtio-trace/Makefile
new file mode 100644
index 000000000000..ef3adfce594c
--- /dev/null
+++ b/tools/virtio/virtio-trace/Makefile
@@ -0,0 +1,14 @@
+CC = gcc
+CFLAGS = -O2 -Wall
+LFLAG = -lpthread
+
+all: trace-agent
+
+.c.o:
+        $(CC) $(CFLAGS) $(LFLAG) -c $^ -o $@
+
+trace-agent: trace-agent.o trace-agent-ctl.o trace-agent-rw.o
+        $(CC) $(CFLAGS) $(LFLAG) -o $@ $^
+
+clean:
+        rm -f *.o trace-agent
diff --git a/tools/virtio/virtio-trace/README b/tools/virtio/virtio-trace/README
new file mode 100644
index 000000000000..b64845b823ab
--- /dev/null
+++ b/tools/virtio/virtio-trace/README
@@ -0,0 +1,118 @@
+Trace Agent for virtio-trace
+============================
+
+Trace agent is a user tool for sending trace data of a guest to a Host in low
+overhead. Trace agent has the following functions:
+ - splice a page of ring-buffer to read_pipe without memory copying
+ - splice the page from write_pipe to virtio-console without memory copying
+ - write trace data to stdout by using -o option
+ - controlled by start/stop orders from a Host
+
+The trace agent operates as follows:
+ 1) Initialize all structures.
+ 2) Create a read/write thread per CPU. Each thread is bound to a CPU.
+    The read/write threads hold it.
+ 3) A controller thread does poll() for a start order of a host.
+ 4) After the controller of the trace agent receives a start order from a host,
+    the controller wake read/write threads.
+ 5) The read/write threads start to read trace data from ring-buffers and
+    write the data to virtio-serial.
+ 6) If the controller receives a stop order from a host, the read/write threads
+    stop to read trace data.
+
+
+Files
+=====
+
+README: this file
+Makefile: Makefile of trace agent for virtio-trace
+trace-agent.c: includes main function, sets up for operating trace agent
+trace-agent.h: includes all structures and some macros
+trace-agent-ctl.c: includes controller function for read/write threads
+trace-agent-rw.c: includes read/write threads function
+
+
+Setup
+=====
+
+To use this trace agent for virtio-trace, we need to prepare some virtio-serial
+I/Fs.
+
+1) Make FIFO in a host
+ virtio-trace uses virtio-serial pipe as trace data paths as to the number
+of CPUs and a control path, so FIFO (named pipe) should be created as follows:
+        # mkdir /tmp/virtio-trace/
+        # mkfifo /tmp/virtio-trace/trace-path-cpu{0,1,2,...,X}.{in,out}
+        # mkfifo /tmp/virtio-trace/agent-ctl-path.{in,out}
+
+For example, if a guest use three CPUs, the names are
+        trace-path-cpu{0,1,2}.{in.out}
+and
+        agent-ctl-path.{in,out}.
+
+2) Set up of virtio-serial pipe in a host
+ Add qemu option to use virtio-serial pipe.
+
+ ##virtio-serial device##
+     -device virtio-serial-pci,id=virtio-serial0\
+ ##control path##
+     -chardev pipe,id=charchannel0,path=/tmp/virtio-trace/agent-ctl-path\
+     -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,\
+      id=channel0,name=agent-ctl-path\
+ ##data path##
+     -chardev pipe,id=charchannel1,path=/tmp/virtio-trace/trace-path-cpu0\
+     -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel0,\
+      id=channel1,name=trace-path-cpu0\
+      ...
+
+If you manage guests with libvirt, add the following tags to domain XML files.
+Then, libvirt passes the same command option to qemu.
+
+        <channel type='pipe'>
+           <source path='/tmp/virtio-trace/agent-ctl-path'/>
+           <target type='virtio' name='agent-ctl-path'/>
+           <address type='virtio-serial' controller='0' bus='0' port='0'/>
+        </channel>
+        <channel type='pipe'>
+           <source path='/tmp/virtio-trace/trace-path-cpu0'/>
+           <target type='virtio' name='trace-path-cpu0'/>
+           <address type='virtio-serial' controller='0' bus='0' port='1'/>
+        </channel>
+        ...
+Here, chardev names are restricted to trace-path-cpuX and agent-ctl-path. For
+example, if a guest use three CPUs, chardev names should be trace-path-cpu0,
+trace-path-cpu1, trace-path-cpu2, and agent-ctl-path.
+
+3) Boot the guest
+ You can find some chardev in /dev/virtio-ports/ in the guest.
+
+
+Run
+===
+
+0) Build trace agent in a guest
+        $ make
+
+1) Enable ftrace in the guest
+ <Example>
+        # echo 1 > /sys/kernel/debug/tracing/events/sched/enable
+
+2) Run trace agent in the guest
+ This agent must be operated as root.
+        # ./trace-agent
+read/write threads in the agent wait for start order from host. If you add -o
+option, trace data are output via stdout in the guest.
+
+3) Open FIFO in a host
+        # cat /tmp/virtio-trace/trace-path-cpu0.out
+If a host does not open these, trace data get stuck in buffers of virtio. Then,
+the guest will stop by specification of chardev in QEMU. This blocking mode may
+be solved in the future.
+
+4) Start to read trace data by ordering from a host
+ A host injects read start order to the guest via virtio-serial.
+        # echo 1 > /tmp/virtio-trace/agent-ctl-path.in
+
+5) Stop to read trace data by ordering from a host
+ A host injects read stop order to the guest via virtio-serial.
+        # echo 0 > /tmp/virtio-trace/agent-ctl-path.in
diff --git a/tools/virtio/virtio-trace/trace-agent-ctl.c b/tools/virtio/virtio-trace/trace-agent-ctl.c
new file mode 100644
index 000000000000..a2d0403c4f94
--- /dev/null
+++ b/tools/virtio/virtio-trace/trace-agent-ctl.c
@@ -0,0 +1,137 @@
+/*
+ * Controller of read/write threads for virtio-trace
+ *
+ * Copyright (C) 2012 Hitachi, Ltd.
+ * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
+ *            Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
+ *
+ * Licensed under GPL version 2 only.
+ *
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <poll.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "trace-agent.h"
+
+#define HOST_MSG_SIZE           256
+#define EVENT_WAIT_MSEC         100
+
+static volatile sig_atomic_t global_signal_val;
+bool global_sig_receive;        /* default false */
+bool global_run_operation;      /* default false*/
+
+/* Handle SIGTERM/SIGINT/SIGQUIT to exit */
+static void signal_handler(int sig)
+{
+        global_signal_val = sig;
+}
+
+int rw_ctl_init(const char *ctl_path)
+{
+        int ctl_fd;
+
+        ctl_fd = open(ctl_path, O_RDONLY);
+        if (ctl_fd == -1) {
+                pr_err("Cannot open ctl_fd\n");
+                goto error;
+        }
+
+        return ctl_fd;
+
+error:
+        exit(EXIT_FAILURE);
+}
+
+static int wait_order(int ctl_fd)
+{
+        struct pollfd poll_fd;
+        int ret = 0;
+
+        while (!global_sig_receive) {
+                poll_fd.fd = ctl_fd;
+                poll_fd.events = POLLIN;
+
+                ret = poll(&poll_fd, 1, EVENT_WAIT_MSEC);
+
+                if (global_signal_val) {
+                        global_sig_receive = true;
+                        pr_info("Receive interrupt %d\n", global_signal_val);
+
+                        /* Wakes rw-threads when they are sleeping */
+                        if (!global_run_operation)
+                                pthread_cond_broadcast(&cond_wakeup);
+
+                        ret = -1;
+                        break;
+                }
+
+                if (ret < 0) {
+                        pr_err("Polling error\n");
+                        goto error;
+                }
+
+                if (ret)
+                        break;
+        };
+
+        return ret;
+
+error:
+        exit(EXIT_FAILURE);
+}
+
+/*
+ * contol read/write threads by handling global_run_operation
+ */
+void *rw_ctl_loop(int ctl_fd)
+{
+        ssize_t rlen;
+        char buf[HOST_MSG_SIZE];
+        int ret;
+
+        /* Setup signal handlers */
+        signal(SIGTERM, signal_handler);
+        signal(SIGINT, signal_handler);
+        signal(SIGQUIT, signal_handler);
+
+        while (!global_sig_receive) {
+
+                ret = wait_order(ctl_fd);
+                if (ret < 0)
+                        break;
+
+                rlen = read(ctl_fd, buf, sizeof(buf));
+                if (rlen < 0) {
+                        pr_err("read data error in ctl thread\n");
+                        goto error;
+                }
+
+                if (rlen == 2 && buf[0] == '1') {
+                        /*
+                         * If host writes '1' to a control path,
+                         * this controller wakes all read/write threads.
+                         */
+                        global_run_operation = true;
+                        pthread_cond_broadcast(&cond_wakeup);
+                        pr_debug("Wake up all read/write threads\n");
+                } else if (rlen == 2 && buf[0] == '0') {
+                        /*
+                         * If host writes '0' to a control path, read/write
+                         * threads will wait for notification from Host.
+                         */
+                        global_run_operation = false;
+                        pr_debug("Stop all read/write threads\n");
+                } else
+                        pr_info("Invalid host notification: %s\n", buf);
+        }
+
+        return NULL;
+
+error:
+        exit(EXIT_FAILURE);
+}
diff --git a/tools/virtio/virtio-trace/trace-agent-rw.c b/tools/virtio/virtio-trace/trace-agent-rw.c
new file mode 100644
index 000000000000..3aace5ea4842
--- /dev/null
+++ b/tools/virtio/virtio-trace/trace-agent-rw.c
@@ -0,0 +1,192 @@
+/*
+ * Read/write thread of a guest agent for virtio-trace
+ *
+ * Copyright (C) 2012 Hitachi, Ltd.
+ * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
+ *            Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
+ *
+ * Licensed under GPL version 2 only.
+ *
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include "trace-agent.h"
+
+#define READ_WAIT_USEC  100000
+
+void *rw_thread_info_new(void)
+{
+        struct rw_thread_info *rw_ti;
+
+        rw_ti = zalloc(sizeof(struct rw_thread_info));
+        if (rw_ti == NULL) {
+                pr_err("rw_thread_info zalloc error\n");
+                exit(EXIT_FAILURE);
+        }
+
+        rw_ti->cpu_num = -1;
+        rw_ti->in_fd = -1;
+        rw_ti->out_fd = -1;
+        rw_ti->read_pipe = -1;
+        rw_ti->write_pipe = -1;
+        rw_ti->pipe_size = PIPE_INIT;
+
+        return rw_ti;
+}
+
+void *rw_thread_init(int cpu, const char *in_path, const char *out_path,
+                                bool stdout_flag, unsigned long pipe_size,
+                                struct rw_thread_info *rw_ti)
+{
+        int data_pipe[2];
+
+        rw_ti->cpu_num = cpu;
+
+        /* set read(input) fd */
+        rw_ti->in_fd = open(in_path, O_RDONLY);
+        if (rw_ti->in_fd == -1) {
+                pr_err("Could not open in_fd (CPU:%d)\n", cpu);
+                goto error;
+        }
+
+        /* set write(output) fd */
+        if (!stdout_flag) {
+                /* virtio-serial output mode */
+                rw_ti->out_fd = open(out_path, O_WRONLY);
+                if (rw_ti->out_fd == -1) {
+                        pr_err("Could not open out_fd (CPU:%d)\n", cpu);
+                        goto error;
+                }
+        } else
+                /* stdout mode */
+                rw_ti->out_fd = STDOUT_FILENO;
+
+        if (pipe2(data_pipe, O_NONBLOCK) < 0) {
+                pr_err("Could not create pipe in rw-thread(%d)\n", cpu);
+                goto error;
+        }
+
+        /*
+         * Size of pipe is 64kB in default based on fs/pipe.c.
+         * To read/write trace data speedy, pipe size is changed.
+         */
+        if (fcntl(*data_pipe, F_SETPIPE_SZ, pipe_size) < 0) {
+                pr_err("Could not change pipe size in rw-thread(%d)\n", cpu);
+                goto error;
+        }
+
+        rw_ti->read_pipe = data_pipe[1];
+        rw_ti->write_pipe = data_pipe[0];
+        rw_ti->pipe_size = pipe_size;
+
+        return NULL;
+
+error:
+        exit(EXIT_FAILURE);
+}
+
+/* Bind a thread to a cpu */
+static void bind_cpu(int cpu_num)
+{
+        cpu_set_t mask;
+
+        CPU_ZERO(&mask);
+        CPU_SET(cpu_num, &mask);
+
+        /* bind my thread to cpu_num by assigning zero to the first argument */
+        if (sched_setaffinity(0, sizeof(mask), &mask) == -1)
+                pr_err("Could not set CPU#%d affinity\n", (int)cpu_num);
+}
+
+static void *rw_thread_main(void *thread_info)
+{
+        ssize_t rlen, wlen;
+        ssize_t ret;
+        struct rw_thread_info *ts = (struct rw_thread_info *)thread_info;
+
+        bind_cpu(ts->cpu_num);
+
+        while (1) {
+                /* Wait for a read order of trace data by Host OS */
+                if (!global_run_operation) {
+                        pthread_mutex_lock(&mutex_notify);
+                        pthread_cond_wait(&cond_wakeup, &mutex_notify);
+                        pthread_mutex_unlock(&mutex_notify);
+                }
+
+                if (global_sig_receive)
+                        break;
+
+                /*
+                 * Each thread read trace_pipe_raw of each cpu bounding the
+                 * thread, so contention of multi-threads does not occur.
+                 */
+                rlen = splice(ts->in_fd, NULL, ts->read_pipe, NULL,
+                                ts->pipe_size, SPLICE_F_MOVE | SPLICE_F_MORE);
+
+                if (rlen < 0) {
+                        pr_err("Splice_read in rw-thread(%d)\n", ts->cpu_num);
+                        goto error;
+                } else if (rlen == 0) {
+                        /*
+                         * If trace data do not exist or are unreadable not
+                         * for exceeding the page size, splice_read returns
+                         * NULL. Then, this waits for being filled the data in a
+                         * ring-buffer.
+                         */
+                        usleep(READ_WAIT_USEC);
+                        pr_debug("Read retry(cpu:%d)\n", ts->cpu_num);
+                        continue;
+                }
+
+                wlen = 0;
+
+                do {
+                        ret = splice(ts->write_pipe, NULL, ts->out_fd, NULL,
+                                        rlen - wlen,
+                                        SPLICE_F_MOVE | SPLICE_F_MORE);
+
+                        if (ret < 0) {
+                                pr_err("Splice_write in rw-thread(%d)\n",
+                                                                ts->cpu_num);
+                                goto error;
+                        } else if (ret == 0)
+                                /*
+                                 * When host reader is not in time for reading
+                                 * trace data, guest will be stopped. This is
+                                 * because char dev in QEMU is not supported
+                                 * non-blocking mode. Then, writer might be
+                                 * sleep in that case.
+                                 * This sleep will be removed by supporting
+                                 * non-blocking mode.
+                                 */
+                                sleep(1);
+                        wlen += ret;
+                } while (wlen < rlen);
+        }
+
+        return NULL;
+
+error:
+        exit(EXIT_FAILURE);
+}
+
+
+pthread_t rw_thread_run(struct rw_thread_info *rw_ti)
+{
+        int ret;
+        pthread_t rw_thread_per_cpu;
+
+        ret = pthread_create(&rw_thread_per_cpu, NULL, rw_thread_main, rw_ti);
+        if (ret != 0) {
+                pr_err("Could not create a rw thread(%d)\n", rw_ti->cpu_num);
+                exit(EXIT_FAILURE);
+        }
+
+        return rw_thread_per_cpu;
+}
diff --git a/tools/virtio/virtio-trace/trace-agent.c b/tools/virtio/virtio-trace/trace-agent.c
new file mode 100644
index 000000000000..0a0a7dd4eff7
--- /dev/null
+++ b/tools/virtio/virtio-trace/trace-agent.c
@@ -0,0 +1,270 @@
+/*
+ * Guest agent for virtio-trace
+ *
+ * Copyright (C) 2012 Hitachi, Ltd.
+ * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
+ *            Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
+ *
+ * Licensed under GPL version 2 only.
+ *
+ */
+
+#define _GNU_SOURCE
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "trace-agent.h"
+
+#define PAGE_SIZE               (sysconf(_SC_PAGE_SIZE))
+#define PIPE_DEF_BUFS           16
+#define PIPE_MIN_SIZE           (PAGE_SIZE*PIPE_DEF_BUFS)
+#define PIPE_MAX_SIZE           (1024*1024)
+#define READ_PATH_FMT   \
+                "/sys/kernel/debug/tracing/per_cpu/cpu%d/trace_pipe_raw"
+#define WRITE_PATH_FMT          "/dev/virtio-ports/trace-path-cpu%d"
+#define CTL_PATH                "/dev/virtio-ports/agent-ctl-path"
+
+pthread_mutex_t mutex_notify = PTHREAD_MUTEX_INITIALIZER;
+pthread_cond_t cond_wakeup = PTHREAD_COND_INITIALIZER;
+
+static int get_total_cpus(void)
+{
+        int nr_cpus = (int)sysconf(_SC_NPROCESSORS_CONF);
+
+        if (nr_cpus <= 0) {
+                pr_err("Could not read cpus\n");
+                goto error;
+        } else if (nr_cpus > MAX_CPUS) {
+                pr_err("Exceed max cpus(%d)\n", (int)MAX_CPUS);
+                goto error;
+        }
+
+        return nr_cpus;
+
+error:
+        exit(EXIT_FAILURE);
+}
+
+static void *agent_info_new(void)
+{
+        struct agent_info *s;
+        int i;
+
+        s = zalloc(sizeof(struct agent_info));
+        if (s == NULL) {
+                pr_err("agent_info zalloc error\n");
+                exit(EXIT_FAILURE);
+        }
+
+        s->pipe_size = PIPE_INIT;
+        s->use_stdout = false;
+        s->cpus = get_total_cpus();
+        s->ctl_fd = -1;
+
+        /* read/write threads init */
+        for (i = 0; i < s->cpus; i++)
+                s->rw_ti[i] = rw_thread_info_new();
+
+        return s;
+}
+
+static unsigned long parse_size(const char *arg)
+{
+        unsigned long value, round;
+        char *ptr;
+
+        value = strtoul(arg, &ptr, 10);
+        switch (*ptr) {
+        case 'K': case 'k':
+                value <<= 10;
+                break;
+        case 'M': case 'm':
+                value <<= 20;
+                break;
+        default:
+                break;
+        }
+
+        if (value > PIPE_MAX_SIZE) {
+                pr_err("Pipe size must be less than 1MB\n");
+                goto error;
+        } else if (value < PIPE_MIN_SIZE) {
+                pr_err("Pipe size must be over 64KB\n");
+                goto error;
+        }
+
+        /* Align buffer size with page unit */
+        round = value & (PAGE_SIZE - 1);
+        value = value - round;
+
+        return value;
+error:
+        return 0;
+}
+
+static void usage(char const *prg)
+{
+        pr_err("usage: %s [-h] [-o] [-s <size of pipe>]\n", prg);
+}
+
+static const char *make_path(int cpu_num, bool this_is_write_path)
+{
+        int ret;
+        char *buf;
+
+        buf = zalloc(PATH_MAX);
+        if (buf == NULL) {
+                pr_err("Could not allocate buffer\n");
+                goto error;
+        }
+
+        if (this_is_write_path)
+                /* write(output) path */
+                ret = snprintf(buf, PATH_MAX, WRITE_PATH_FMT, cpu_num);
+        else
+                /* read(input) path */
+                ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, cpu_num);
+
+        if (ret <= 0) {
+                pr_err("Failed to generate %s path(CPU#%d):%d\n",
+                        this_is_write_path ? "read" : "write", cpu_num, ret);
+                goto error;
+        }
+
+        return buf;
+
+error:
+        free(buf);
+        return NULL;
+}
+
+static const char *make_input_path(int cpu_num)
+{
+        return make_path(cpu_num, false);
+}
+
+static const char *make_output_path(int cpu_num)
+{
+        return make_path(cpu_num, true);
+}
+
+static void *agent_info_init(struct agent_info *s)
+{
+        int cpu;
+        const char *in_path = NULL;
+        const char *out_path = NULL;
+
+        /* init read/write threads */
+        for (cpu = 0; cpu < s->cpus; cpu++) {
+                /* set read(input) path per read/write thread */
+                in_path = make_input_path(cpu);
+                if (in_path == NULL)
+                        goto error;
+
+                /* set write(output) path per read/write thread*/
+                if (!s->use_stdout) {
+                        out_path = make_output_path(cpu);
+                        if (out_path == NULL)
+                                goto error;
+                } else
+                        /* stdout mode */
+                        pr_debug("stdout mode\n");
+
+                rw_thread_init(cpu, in_path, out_path, s->use_stdout,
+                                                s->pipe_size, s->rw_ti[cpu]);
+        }
+
+        /* init controller of read/write threads */
+        s->ctl_fd = rw_ctl_init((const char *)CTL_PATH);
+
+        return NULL;
+
+error:
+        exit(EXIT_FAILURE);
+}
+
+static void *parse_args(int argc, char *argv[], struct agent_info *s)
+{
+        int cmd;
+        unsigned long size;
+
+        while ((cmd = getopt(argc, argv, "hos:")) != -1) {
+                switch (cmd) {
+                /* stdout mode */
+                case 'o':
+                        s->use_stdout = true;
+                        break;
+                /* size of pipe */
+                case 's':
+                        size = parse_size(optarg);
+                        if (size == 0)
+                                goto error;
+                        s->pipe_size = size;
+                        break;
+                case 'h':
+                default:
+                        usage(argv[0]);
+                        goto error;
+                }
+        }
+
+        agent_info_init(s);
+
+        return NULL;
+
+error:
+        exit(EXIT_FAILURE);
+}
+
+static void agent_main_loop(struct agent_info *s)
+{
+        int cpu;
+        pthread_t rw_thread_per_cpu[MAX_CPUS];
+
+        /* Start all read/write threads */
+        for (cpu = 0; cpu < s->cpus; cpu++)
+                rw_thread_per_cpu[cpu] = rw_thread_run(s->rw_ti[cpu]);
+
+        rw_ctl_loop(s->ctl_fd);
+
+        /* Finish all read/write threads */
+        for (cpu = 0; cpu < s->cpus; cpu++) {
+                int ret;
+
+                ret = pthread_join(rw_thread_per_cpu[cpu], NULL);
+                if (ret != 0) {
+                        pr_err("pthread_join() error:%d (cpu %d)\n", ret, cpu);
+                        exit(EXIT_FAILURE);
+                }
+        }
+}
+
+static void agent_info_free(struct agent_info *s)
+{
+        int i;
+
+        close(s->ctl_fd);
+        for (i = 0; i < s->cpus; i++) {
+                close(s->rw_ti[i]->in_fd);
+                close(s->rw_ti[i]->out_fd);
+                close(s->rw_ti[i]->read_pipe);
+                close(s->rw_ti[i]->write_pipe);
+                free(s->rw_ti[i]);
+        }
+        free(s);
+}
+
+int main(int argc, char *argv[])
+{
+        struct agent_info *s = NULL;
+
+        s = agent_info_new();
+        parse_args(argc, argv, s);
+
+        agent_main_loop(s);
+
+        agent_info_free(s);
+
+        return 0;
+}
diff --git a/tools/virtio/virtio-trace/trace-agent.h b/tools/virtio/virtio-trace/trace-agent.h
new file mode 100644
index 000000000000..8de79bfeaa73
--- /dev/null
+++ b/tools/virtio/virtio-trace/trace-agent.h
@@ -0,0 +1,75 @@
+#ifndef __TRACE_AGENT_H__
+#define __TRACE_AGENT_H__
+#include <pthread.h>
+#include <stdbool.h>
+
+#define MAX_CPUS        256
+#define PIPE_INIT       (1024*1024)
+
+/*
+ * agent_info - structure managing total information of guest agent
+ * @pipe_size:  size of pipe (default 1MB)
+ * @use_stdout: set to true when o option is added (default false)
+ * @cpus:       total number of CPUs
+ * @ctl_fd:     fd of control path, /dev/virtio-ports/agent-ctl-path
+ * @rw_ti:      structure managing information of read/write threads
+ */
+struct agent_info {
+        unsigned long pipe_size;
+        bool use_stdout;
+        int cpus;
+        int ctl_fd;
+        struct rw_thread_info *rw_ti[MAX_CPUS];
+};
+
+/*
+ * rw_thread_info - structure managing a read/write thread a cpu
+ * @cpu_num:    cpu number operating this read/write thread
+ * @in_fd:      fd of reading trace data path in cpu_num
+ * @out_fd:     fd of writing trace data path in cpu_num
+ * @read_pipe:  fd of read pipe
+ * @write_pipe: fd of write pipe
+ * @pipe_size:  size of pipe (default 1MB)
+ */
+struct rw_thread_info {
+        int cpu_num;
+        int in_fd;
+        int out_fd;
+        int read_pipe;
+        int write_pipe;
+        unsigned long pipe_size;
+};
+
+/* use for stopping rw threads */
+extern bool global_sig_receive;
+
+/* use for notification */
+extern bool global_run_operation;
+extern pthread_mutex_t mutex_notify;
+extern pthread_cond_t cond_wakeup;
+
+/* for controller of read/write threads */
+extern int rw_ctl_init(const char *ctl_path);
+extern void *rw_ctl_loop(int ctl_fd);
+
+/* for trace read/write thread */
+extern void *rw_thread_info_new(void);
+extern void *rw_thread_init(int cpu, const char *in_path, const char *out_path,
+                        bool stdout_flag, unsigned long pipe_size,
+                        struct rw_thread_info *rw_ti);
+extern pthread_t rw_thread_run(struct rw_thread_info *rw_ti);
+
+static inline void *zalloc(size_t size)
+{
+        return calloc(1, size);
+}
+
+#define pr_err(format, ...) fprintf(stderr, format, ## __VA_ARGS__)
+#define pr_info(format, ...) fprintf(stdout, format, ## __VA_ARGS__)
+#ifdef DEBUG
+#define pr_debug(format, ...) fprintf(stderr, format, ## __VA_ARGS__)
+#else
+#define pr_debug(format, ...) do {} while (0)
+#endif
+
+#endif /*__TRACE_AGENT_H__*/