kvm tools: Add 'kvm stat' command

This patch adds 'kvm stat' command that allows retrieving statistics out of
a running guest.

Currently the only supported statistics are memory statistics, available using the
'--memory' parameter.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

Documentation/kvm-stat.txt

@@ -0,0 +1,19 @@
+kvm-stat(1)
+================
+
+NAME
+----
+kvm-stat - Print statistics about a running instance
+
+SYNOPSIS
+--------
+[verse]
+'kvm [command] [-n instance] [-p instance pid] [--all]'
+
+DESCRIPTION
+-----------
+The command prints statistics about a running instance.
+For a list of running instances see 'kvm list'.
+
+Commands:
+ --memory, -m	Display memory statistics

Makefile

@@ -24,6 +24,7 @@ OBJS	+= builtin-balloon.o
 OBJS	+= builtin-debug.o
 OBJS	+= builtin-help.o
 OBJS	+= builtin-list.o
+OBJS	+= builtin-stat.o
 OBJS	+= builtin-pause.o
 OBJS	+= builtin-resume.o
 OBJS	+= builtin-run.o

builtin-stat.c

@@ -0,0 +1,79 @@
+#include <kvm/util.h>
+#include <kvm/kvm-cmd.h>
+#include <kvm/builtin-stat.h>
+#include <kvm/kvm.h>
+#include <kvm/parse-options.h>
+
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+
+static bool mem;
+static bool all;
+static u64 instance_pid;
+static const char *instance_name;
+
+static const char * const stat_usage[] = {
+	"kvm stat [command] [--all] [-n name] [-p pid]",
+	NULL
+};
+
+static const struct option stat_options[] = {
+	OPT_GROUP("Commands options:"),
+	OPT_BOOLEAN('m', "memory", &mem, "Display memory statistics"),
+	OPT_GROUP("Instance options:"),
+	OPT_BOOLEAN('a', "all", &all, "All instances"),
+	OPT_STRING('n', "name", &instance_name, "name", "Instance name"),
+	OPT_U64('p', "pid", &instance_pid, "Instance pid"),
+	OPT_END()
+};
+
+static void parse_stat_options(int argc, const char **argv)
+{
+	while (argc != 0) {
+		argc = parse_options(argc, argv, stat_options, stat_usage,
+				PARSE_OPT_STOP_AT_NON_OPTION);
+		if (argc != 0)
+			kvm_stat_help();
+	}
+}
+
+void kvm_stat_help(void)
+{
+	usage_with_options(stat_usage, stat_options);
+}
+
+static int do_memstat(const char *name, int pid)
+{
+	printf("Sending memstat command to %s, output should be on the targets' terminal.\n", name);
+	return kill(pid, SIGKVMMEMSTAT);
+}
+
+int kvm_cmd_stat(int argc, const char **argv, const char *prefix)
+{
+	parse_stat_options(argc, argv);
+
+	if (!mem)
+		usage_with_options(stat_usage, stat_options);
+
+	if (mem && all)
+		return kvm__enumerate_instances(do_memstat);
+
+	if (instance_name == NULL &&
+	    instance_pid == 0)
+		kvm_stat_help();
+
+	if (instance_name)
+		instance_pid = kvm__get_pid_by_instance(instance_name);
+
+	if (instance_pid <= 0)
+		die("Failed locating instance");
+
+	if (mem) {
+		printf("Sending memstat command to designated instance, output should be on the targets' terminal.\n");
+
+		return kill(instance_pid, SIGKVMMEMSTAT);
+	}
+
+	return 0;
+}

command-list.txt

@@ -10,3 +10,4 @@ kvm-list			common
 kvm-debug			common
 kvm-balloon			common
 kvm-stop			common
+kvm-stat			common

include/kvm/builtin-stat.h

@@ -0,0 +1,7 @@
+#ifndef KVM__STAT_H
+#define KVM__STAT_H
+
+int kvm_cmd_stat(int argc, const char **argv, const char *prefix);
+void kvm_stat_help(void);
+
+#endif

include/kvm/kvm.h

@@ -22,6 +22,7 @@
 #define SIGKVMDELMEM		(SIGRTMIN + 3)
 #define SIGKVMSTOP		(SIGRTMIN + 4)
 #define SIGKVMRESUME		(SIGRTMIN + 5)
+#define SIGKVMMEMSTAT		(SIGRTMIN + 6)
 
 struct kvm {
 	int			sys_fd;		/* For system ioctls(), i.e. /dev/kvm */

kvm-cmd.c

@@ -12,6 +12,7 @@
 #include "kvm/builtin-list.h"
 #include "kvm/builtin-version.h"
 #include "kvm/builtin-stop.h"
+#include "kvm/builtin-stat.h"
 #include "kvm/builtin-help.h"
 #include "kvm/kvm-cmd.h"
 #include "kvm/builtin-run.h"
@@ -26,6 +27,7 @@ struct cmd_struct kvm_commands[] = {
 	{ "version",	kvm_cmd_version,	NULL,			0 },
 	{ "--version",	kvm_cmd_version,	NULL,			0 },
 	{ "stop",	kvm_cmd_stop,		kvm_stop_help,		0 },
+	{ "stat",	kvm_cmd_stat,		kvm_stat_help,		0 },
 	{ "help",	kvm_cmd_help,		NULL,			0 },
 	{ "run",	kvm_cmd_run,		kvm_run_help,		0 },
 	{ NULL,		NULL,			NULL,			0 },

virtio/balloon.c

@@ -21,10 +21,11 @@
 #include <sys/stat.h>
 #include <pthread.h>
 
-#define NUM_VIRT_QUEUES		2
+#define NUM_VIRT_QUEUES		3
 #define VIRTIO_BLN_QUEUE_SIZE	128
 #define VIRTIO_BLN_INFLATE	0
 #define VIRTIO_BLN_DEFLATE	1
+#define VIRTIO_BLN_STATS	2
 
 struct bln_dev {
 	struct pci_device_header pci_hdr;
@@ -41,6 +42,12 @@ struct bln_dev {
 	struct virt_queue	vqs[NUM_VIRT_QUEUES];
 	struct thread_pool__job	jobs[NUM_VIRT_QUEUES];
 
+	struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
+	struct virtio_balloon_stat *cur_stat;
+	u32			cur_stat_head;
+	u16			stat_count;
+	int			stat_waitfd;
+
 	struct virtio_balloon_config config;
 };
 
@@ -127,7 +134,7 @@ static bool virtio_bln_do_io_request(struct kvm *kvm, struct bln_dev *bdev, stru
 		if (queue == &bdev->vqs[VIRTIO_BLN_INFLATE]) {
 			madvise(guest_ptr, 1 << VIRTIO_BALLOON_PFN_SHIFT, MADV_DONTNEED);
 			bdev->config.actual++;
-		} else {
+		} else if (queue == &bdev->vqs[VIRTIO_BLN_DEFLATE]) {
 			bdev->config.actual--;
 		}
 	}
@@ -137,10 +144,46 @@ static bool virtio_bln_do_io_request(struct kvm *kvm, struct bln_dev *bdev, stru
 	return true;
 }
 
+static bool virtio_bln_do_stat_request(struct kvm *kvm, struct bln_dev *bdev, struct virt_queue *queue)
+{
+	struct iovec iov[VIRTIO_BLN_QUEUE_SIZE];
+	u16 out, in, head;
+	struct virtio_balloon_stat *stat;
+	u64 wait_val = 1;
+
+	head = virt_queue__get_iov(queue, iov, &out, &in, kvm);
+	stat = iov[0].iov_base;
+
+	/* Initial empty stat buffer */
+	if (bdev->cur_stat == NULL) {
+		bdev->cur_stat = stat;
+		bdev->cur_stat_head = head;
+
+		return true;
+	}
+
+	memcpy(bdev->stats, stat, iov[0].iov_len);
+
+	bdev->stat_count = iov[0].iov_len / sizeof(struct virtio_balloon_stat);
+	bdev->cur_stat = stat;
+	bdev->cur_stat_head = head;
+
+	if (write(bdev->stat_waitfd, &wait_val, sizeof(wait_val)) <= 0)
+		return -EFAULT;
+
+	return 1;
+}
+
 static void virtio_bln_do_io(struct kvm *kvm, void *param)
 {
 	struct virt_queue *vq = param;
 
+	if (vq == &bdev.vqs[VIRTIO_BLN_STATS]) {
+		virtio_bln_do_stat_request(kvm, &bdev, vq);
+		virt_queue__trigger_irq(vq, bdev.pci_hdr.irq_line, &bdev.isr, kvm);
+		return;
+	}
+
 	while (virt_queue__available(vq)) {
 		virtio_bln_do_io_request(kvm, &bdev, vq);
 		virt_queue__trigger_irq(vq, bdev.pci_hdr.irq_line, &bdev.isr, kvm);
@@ -218,15 +261,70 @@ static struct ioport_operations virtio_bln_io_ops = {
 	.io_out				= virtio_bln_pci_io_out,
 };
 
+static int virtio_bln__collect_stats(void)
+{
+	u64 tmp;
+
+	virt_queue__set_used_elem(&bdev.vqs[VIRTIO_BLN_STATS], bdev.cur_stat_head,
+				  sizeof(struct virtio_balloon_stat));
+	virt_queue__trigger_irq(&bdev.vqs[VIRTIO_BLN_STATS], bdev.pci_hdr.irq_line,
+				&bdev.isr, kvm);
+
+	if (read(bdev.stat_waitfd, &tmp, sizeof(tmp)) <= 0)
+		return -EFAULT;
+
+	return 0;
+}
+
+static int virtio_bln__print_stats(void)
+{
+	u16 i;
+
+	if (virtio_bln__collect_stats() < 0)
+		return -EFAULT;
+
+	printf("\n\n\t*** Guest memory statistics ***\n\n");
+	for (i = 0; i < bdev.stat_count; i++) {
+		switch (bdev.stats[i].tag) {
+		case VIRTIO_BALLOON_S_SWAP_IN:
+			printf("The amount of memory that has been swapped in (in bytes):");
+			break;
+		case VIRTIO_BALLOON_S_SWAP_OUT:
+			printf("The amount of memory that has been swapped out to disk (in bytes):");
+			break;
+		case VIRTIO_BALLOON_S_MAJFLT:
+			printf("The number of major page faults that have occurred:");
+			break;
+		case VIRTIO_BALLOON_S_MINFLT:
+			printf("The number of minor page faults that have occurred:");
+			break;
+		case VIRTIO_BALLOON_S_MEMFREE:
+			printf("The amount of memory not being used for any purpose (in bytes):");
+			break;
+		case VIRTIO_BALLOON_S_MEMTOT:
+			printf("The total amount of memory available (in bytes):");
+			break;
+		}
+		printf("%llu\n", bdev.stats[i].val);
+	}
+	printf("\n");
+
+	return 0;
+}
+
 static void handle_sigmem(int sig)
 {
 	if (sig == SIGKVMADDMEM) {
 		bdev.config.num_pages += 256;
-	} else {
+	} else if (sig == SIGKVMDELMEM) {
 		if (bdev.config.num_pages < 256)
 			return;
 
 		bdev.config.num_pages -= 256;
+	} else if (sig == SIGKVMMEMSTAT) {
+		virtio_bln__print_stats();
+
+		return;
 	}
 
 	/* Notify that the configuration space has changed */
@@ -241,6 +339,7 @@ void virtio_bln__init(struct kvm *kvm)
 
 	signal(SIGKVMADDMEM, handle_sigmem);
 	signal(SIGKVMDELMEM, handle_sigmem);
+	signal(SIGKVMMEMSTAT, handle_sigmem);
 
 	bdev_base_addr = ioport__register(IOPORT_EMPTY, &virtio_bln_io_ops, IOPORT_SIZE, &bdev);
 
@@ -262,7 +361,8 @@ void virtio_bln__init(struct kvm *kvm)
 
 	bdev.pci_hdr.irq_pin	= pin;
 	bdev.pci_hdr.irq_line	= line;
-	bdev.host_features	= 0;
+	bdev.host_features	= 1 << VIRTIO_BALLOON_F_STATS_VQ;
+	bdev.stat_waitfd	= eventfd(0, 0);
 	memset(&bdev.config, 0, sizeof(struct virtio_balloon_config));
 
 	pci__register(&bdev.pci_hdr, dev);