1 files changed, 388 insertions, 0 deletions
diff --git a/tracecmd/trace-vm.c b/tracecmd/trace-vm.c
new file mode 100644
index 00000000..57dbef8d
--- /dev/null
+++ b/tracecmd/trace-vm.c
@@ -0,0 +1,388 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2008, 2009, 2010 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2020, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <limits.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "trace-local.h"
+#include "trace-msg.h"
+
+static struct trace_guest *guests;
+static size_t guests_len;
+
+static struct trace_guest *get_guest_by_cid(unsigned int guest_cid)
+{
+	int i;
+
+	if (!guests)
+		return NULL;
+
+	for (i = 0; i < guests_len; i++)
+		if (guest_cid == guests[i].cid)
+			return guests + i;
+	return NULL;
+}
+
+static struct trace_guest *get_guest_by_name(const char *name)
+{
+	int i;
+
+	if (!guests)
+		return NULL;
+
+	for (i = 0; i < guests_len; i++)
+		if (strcmp(name, guests[i].name) == 0)
+			return guests + i;
+	return NULL;
+}
+
+bool trace_have_guests_pid(void)
+{
+	for (int i = 0; i < guests_len; i++) {
+		if (guests[i].pid < 0)
+			return false;
+	}
+
+	return true;
+}
+
+static struct trace_guest *add_guest(unsigned int cid, const char *name)
+{
+	guests = realloc(guests, (guests_len + 1) * sizeof(*guests));
+	if (!guests)
+		die("allocating new guest");
+	memset(&guests[guests_len], 0, sizeof(struct trace_guest));
+	guests[guests_len].name = strdup(name);
+	if (!guests[guests_len].name)
+		die("allocating guest name");
+	guests[guests_len].cid = cid;
+	guests[guests_len].pid = -1;
+	guests_len++;
+
+	return &guests[guests_len - 1];
+}
+
+static struct tracefs_instance *start_trace_connect(void)
+{
+	struct tracefs_instance *open_instance;
+
+	open_instance = tracefs_instance_create("vsock_find_pid");
+	if (!open_instance)
+		return NULL;
+
+	tracefs_event_enable(open_instance, "sched", "sched_waking");
+	tracefs_event_enable(open_instance, "kvm", "kvm_exit");
+	tracefs_trace_on(open_instance);
+	return open_instance;
+}
+
+struct pids {
+	struct pids		*next;
+	int			pid;
+};
+
+struct trace_fields {
+	struct tep_event		*sched_waking;
+	struct tep_event		*kvm_exit;
+	struct tep_format_field		*common_pid;
+	struct tep_format_field		*sched_next;
+	struct pids			*pids;
+	int				found_pid;
+};
+
+static void free_pids(struct pids *pids)
+{
+	struct pids *next;
+
+	while (pids) {
+		next = pids;
+		pids = pids->next;
+		free(next);
+	}
+}
+
+static void add_pid(struct pids **pids, int pid)
+{
+	struct pids *new_pid;
+
+	new_pid = malloc(sizeof(*new_pid));
+	if (!new_pid)
+		return;
+
+	new_pid->pid = pid;
+	new_pid->next = *pids;
+	*pids = new_pid;
+}
+
+static bool match_pid(struct pids *pids, int pid)
+{
+	while (pids) {
+		if (pids->pid == pid)
+			return true;
+		pids = pids->next;
+	}
+	return false;
+}
+
+static int callback(struct tep_event *event, struct tep_record *record, int cpu,
+		    void *data)
+{
+	struct trace_fields *fields = data;
+	struct tep_handle *tep = event->tep;
+	unsigned long long val;
+	int flags;
+	int type;
+	int pid;
+	int ret;
+
+	ret = tep_read_number_field(fields->common_pid, record->data, &val);
+	if (ret < 0)
+		return 0;
+
+	flags = tep_data_flags(tep, record);
+
+	/* Ignore events in interrupts */
+	if (flags & (TRACE_FLAG_HARDIRQ | TRACE_FLAG_SOFTIRQ))
+		return 0;
+
+	/*
+	 * First make sure that this event comes from a PID from
+	 * this task (or a task woken by this task)
+	 */
+	pid = val;
+	if (!match_pid(fields->pids, pid))
+		return 0;
+
+	type = tep_data_type(tep, record);
+
+	/*
+	 * If this event is a kvm_exit, we have our PID
+	 * and we can stop processing.
+	 */
+	if (type == fields->kvm_exit->id) {
+		fields->found_pid = pid;
+		return -1;
+	}
+
+	if (type != fields->sched_waking->id)
+		return 0;
+
+	ret = tep_read_number_field(fields->sched_next, record->data, &val);
+	if (ret < 0)
+		return 0;
+
+	/* This is a task woken by our task or a chain of wake ups */
+	add_pid(&fields->pids, (int)val);
+	return 0;
+}
+
+static int find_tgid(int pid)
+{
+	FILE *fp;
+	char *path;
+	char *buf = NULL;
+	char *save;
+	size_t l = 0;
+	int tgid = -1;
+
+	if (asprintf(&path, "/proc/%d/status", pid) < 0)
+		return -1;
+
+	fp = fopen(path, "r");
+	free(path);
+	if (!fp)
+		return -1;
+
+	while (getline(&buf, &l, fp) > 0) {
+		char *tok;
+
+		if (strncmp(buf, "Tgid:", 5) != 0)
+			continue;
+		tok = strtok_r(buf, ":", &save);
+		if (!tok)
+			continue;
+		tok = strtok_r(NULL, ":", &save);
+		if (!tok)
+			continue;
+		while (isspace(*tok))
+			tok++;
+		tgid = strtol(tok, NULL, 0);
+		break;
+	}
+	free(buf);
+	fclose(fp);
+
+	return tgid;
+}
+
+static int stop_trace_connect(struct tracefs_instance *open_instance)
+{
+	const char *systems[] = { "kvm", "sched", NULL};
+	struct tep_handle *tep;
+	struct trace_fields trace_fields;
+	int tgid = -1;
+
+	if (!open_instance)
+		return -1;
+
+	/* The connection is finished, stop tracing, we have what we want */
+	tracefs_trace_off(open_instance);
+	tracefs_event_disable(open_instance, NULL, NULL);
+
+	tep = tracefs_local_events_system(NULL, systems);
+
+	trace_fields.sched_waking = tep_find_event_by_name(tep, "sched", "sched_waking");
+	if (!trace_fields.sched_waking)
+		goto out;
+	trace_fields.kvm_exit = tep_find_event_by_name(tep, "kvm", "kvm_exit");
+	if (!trace_fields.kvm_exit)
+		goto out;
+	trace_fields.common_pid = tep_find_common_field(trace_fields.sched_waking,
+							"common_pid");
+	if (!trace_fields.common_pid)
+		goto out;
+	trace_fields.sched_next = tep_find_any_field(trace_fields.sched_waking,
+							"pid");
+	if (!trace_fields.sched_next)
+		goto out;
+
+	trace_fields.found_pid = -1;
+	trace_fields.pids = NULL;
+	add_pid(&trace_fields.pids, getpid());
+	tracefs_iterate_raw_events(tep, open_instance, NULL, 0, callback, &trace_fields);
+	free_pids(trace_fields.pids);
+ out:
+	tracefs_instance_destroy(open_instance);
+	tracefs_instance_free(open_instance);
+
+	if (trace_fields.found_pid > 0)
+		tgid = find_tgid(trace_fields.found_pid);
+
+	return tgid;
+}
+
+/*
+ * In order to find the guest that is associated to the given cid,
+ * trace the sched_waking and kvm_exit events, connect to the cid
+ * (doesn't matter what port, use -1 to not connect to anything)
+ * and find what task gets woken up from this code and calls kvm_exit,
+ * then that is the task that is running the guest.
+ * Then look at the /proc/<guest-pid>/status file to find the task group
+ * id (Tgid), and this is the PID of the task running all the threads.
+ */
+static void find_pid_by_cid(struct trace_guest *guest)
+{
+	struct tracefs_instance *instance;
+	int fd;
+
+	instance = start_trace_connect();
+	fd = trace_vsock_open(guest->cid, -1);
+	guest->pid = stop_trace_connect(instance);
+	/* Just in case! */
+	if (fd >= 0)
+		close(fd);
+}
+
+struct trace_guest *trace_get_guest(unsigned int cid, const char *name)
+{
+	struct trace_guest *guest = NULL;
+
+	if (name) {
+		guest = get_guest_by_name(name);
+		if (guest)
+			return guest;
+	}
+
+	if (cid > 0) {
+		guest = get_guest_by_cid(cid);
+		if (!guest && name) {
+			guest = add_guest(cid, name);
+			if (guest)
+				find_pid_by_cid(guest);
+		}
+	}
+	return guest;
+}
+
+#define VM_CID_CMD	"virsh dumpxml"
+#define VM_CID_LINE	"<cid auto="
+#define VM_CID_ID	"address='"
+static void read_guest_cid(char *name)
+{
+	struct trace_guest *guest;
+	char *cmd = NULL;
+	char line[512];
+	char *cid;
+	unsigned int cid_id = 0;
+	FILE *f;
+
+	asprintf(&cmd, "%s %s", VM_CID_CMD, name);
+	f = popen(cmd, "r");
+	free(cmd);
+	if (f == NULL)
+		return;
+
+	while (fgets(line, sizeof(line), f) != NULL) {
+		if (!strstr(line, VM_CID_LINE))
+			continue;
+		cid = strstr(line, VM_CID_ID);
+		if (!cid)
+			continue;
+		cid_id = strtol(cid + strlen(VM_CID_ID), NULL, 10);
+		if ((cid_id == INT_MIN || cid_id == INT_MAX) && errno == ERANGE)
+			continue;
+		guest = add_guest(cid_id, name);
+		if (guest)
+			find_pid_by_cid(guest);
+		break;
+	}
+
+	/* close */
+	pclose(f);
+}
+
+#define VM_NAME_CMD	"virsh list --name"
+void read_qemu_guests(void)
+{
+	char name[256];
+	FILE *f;
+
+	f = popen(VM_NAME_CMD, "r");
+	if (f == NULL)
+		return;
+
+	while (fgets(name, sizeof(name), f) != NULL) {
+		if (name[0] == '\n')
+			continue;
+		if (name[strlen(name) - 1] == '\n')
+			name[strlen(name) - 1] = '\0';
+		read_guest_cid(name);
+	}
+
+	/* close */
+	pclose(f);
+}
+
+int get_guest_vcpu_pid(unsigned int guest_cid, unsigned int guest_vcpu)
+{
+	int i;
+
+	if (!guests)
+		return -1;
+
+	for (i = 0; i < guests_len; i++) {
+		if (guests[i].cpu_pid < 0 || guest_vcpu >= guests[i].cpu_max)
+			continue;
+		if (guest_cid == guests[i].cid)
+			return guests[i].cpu_pid[guest_vcpu];
+	}
+	return -1;
+}