hw/virtio-balloon.c - third_party/qemu - Git at Google

 /*
  * Virtio Balloon Device
  *
  * Copyright IBM, Corp. 2008
  * Copyright (C) 2011 Red Hat, Inc.
  * Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>
  *
  * Authors:
  *  Anthony Liguori   <aliguori@us.ibm.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
  *
  */

 #include "iov.h"
 #include "qemu-common.h"
 #include "virtio.h"
 #include "pc.h"
 #include "cpu.h"
 #include "monitor.h"
 #include "balloon.h"
 #include "virtio-balloon.h"
 #include "kvm.h"
 #include "qlist.h"
 #include "qint.h"
 #include "qstring.h"

 #if defined(__linux__)
 #include <sys/mman.h>
 #endif

 /* Disable guest-provided stats by now (https://bugzilla.redhat.com/show_bug.cgi?id=623903) */
 #define ENABLE_GUEST_STATS   0


 typedef struct VirtIOBalloon
 {
     VirtIODevice vdev;
     VirtQueue *ivq, *dvq, *svq;
     uint32_t num_pages;
     uint32_t actual;
     uint64_t stats[VIRTIO_BALLOON_S_NR];
     VirtQueueElement stats_vq_elem;
     size_t stats_vq_offset;
     MonitorCompletion *stats_callback;
     void *stats_opaque_callback_data;
     DeviceState *qdev;
 } VirtIOBalloon;

 static VirtIOBalloon *to_virtio_balloon(VirtIODevice *vdev)
 {
     return (VirtIOBalloon *)vdev;
 }

 static void balloon_page(void *addr, int deflate)
 {
 #if defined(__linux__)
     if (!kvm_enabled() || kvm_has_sync_mmu())
         qemu_madvise(addr, TARGET_PAGE_SIZE,
                 deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
 #endif
 }

 /*
  * reset_stats - Mark all items in the stats array as unset
  *
  * This function needs to be called at device intialization and before
  * before updating to a set of newly-generated stats.  This will ensure that no
  * stale values stick around in case the guest reports a subset of the supported
  * statistics.
  */
 static inline void reset_stats(VirtIOBalloon *dev)
 {
     int i;
     for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
 }

 static void stat_put(QDict *dict, const char *label, uint64_t val)
 {
     if (val != -1)
         qdict_put(dict, label, qint_from_int(val));
 }

 static QObject *get_stats_qobject(VirtIOBalloon *dev)
 {
     QDict *dict = qdict_new();
     uint64_t actual = ram_size - ((uint64_t) dev->actual <<
                                   VIRTIO_BALLOON_PFN_SHIFT);

     stat_put(dict, "actual", actual);
 #if ENABLE_GUEST_STATS
     stat_put(dict, "mem_swapped_in", dev->stats[VIRTIO_BALLOON_S_SWAP_IN]);
     stat_put(dict, "mem_swapped_out", dev->stats[VIRTIO_BALLOON_S_SWAP_OUT]);
     stat_put(dict, "major_page_faults", dev->stats[VIRTIO_BALLOON_S_MAJFLT]);
     stat_put(dict, "minor_page_faults", dev->stats[VIRTIO_BALLOON_S_MINFLT]);
     stat_put(dict, "free_mem", dev->stats[VIRTIO_BALLOON_S_MEMFREE]);
     stat_put(dict, "total_mem", dev->stats[VIRTIO_BALLOON_S_MEMTOT]);
 #endif

     return QOBJECT(dict);
 }

 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOBalloon *s = to_virtio_balloon(vdev);
     VirtQueueElement elem;

     while (virtqueue_pop(vq, &elem)) {
         size_t offset = 0;
         uint32_t pfn;

         while (iov_to_buf(elem.out_sg, elem.out_num, &pfn, offset, 4) == 4) {
             ram_addr_t pa;
             ram_addr_t addr;

             pa = (ram_addr_t)ldl_p(&pfn) << VIRTIO_BALLOON_PFN_SHIFT;
             offset += 4;

             addr = cpu_get_physical_page_desc(pa);
             if ((addr & ~TARGET_PAGE_MASK) != IO_MEM_RAM)
                 continue;

             /* Using qemu_get_ram_ptr is bending the rules a bit, but
                should be OK because we only want a single page.  */
             balloon_page(qemu_get_ram_ptr(addr), !!(vq == s->dvq));
         }

         virtqueue_push(vq, &elem, offset);
         virtio_notify(vdev, vq);
     }
 }

 static void complete_stats_request(VirtIOBalloon *vb)
 {
     QObject *stats;

     if (!vb->stats_opaque_callback_data)
         return;

     stats = get_stats_qobject(vb);
     vb->stats_callback(vb->stats_opaque_callback_data, stats);
     qobject_decref(stats);
     vb->stats_opaque_callback_data = NULL;
     vb->stats_callback = NULL;
 }

 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
     VirtQueueElement *elem = &s->stats_vq_elem;
     VirtIOBalloonStat stat;
     size_t offset = 0;

     if (!virtqueue_pop(vq, elem)) {
         return;
     }

     /* Initialize the stats to get rid of any stale values.  This is only
      * needed to handle the case where a guest supports fewer stats than it
      * used to (ie. it has booted into an old kernel).
      */
     reset_stats(s);

     while (iov_to_buf(elem->out_sg, elem->out_num, &stat, offset, sizeof(stat))
            == sizeof(stat)) {
         uint16_t tag = tswap16(stat.tag);
         uint64_t val = tswap64(stat.val);

         offset += sizeof(stat);
         if (tag < VIRTIO_BALLOON_S_NR)
             s->stats[tag] = val;
     }
     s->stats_vq_offset = offset;

     complete_stats_request(s);
 }

 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
 {
     VirtIOBalloon *dev = to_virtio_balloon(vdev);
     struct virtio_balloon_config config;

     config.num_pages = cpu_to_le32(dev->num_pages);
     config.actual = cpu_to_le32(dev->actual);

     memcpy(config_data, &config, 8);
 }

 static void virtio_balloon_set_config(VirtIODevice *vdev,
                                       const uint8_t *config_data)
 {
     VirtIOBalloon *dev = to_virtio_balloon(vdev);
     struct virtio_balloon_config config;
     memcpy(&config, config_data, 8);
     dev->actual = le32_to_cpu(config.actual);
 }

 static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
 {
     f |= (1 << VIRTIO_BALLOON_F_STATS_VQ);
     return f;
 }

 static void virtio_balloon_stat(void *opaque, MonitorCompletion cb,
                                 void *cb_data)
 {
     VirtIOBalloon *dev = opaque;

     /* For now, only allow one request at a time.  This restriction can be
      * removed later by queueing callback and data pairs.
      */
     if (dev->stats_callback != NULL) {
         return;
     }
     dev->stats_callback = cb;
     dev->stats_opaque_callback_data = cb_data;

     if (ENABLE_GUEST_STATS
         && (dev->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ))) {
         virtqueue_push(dev->svq, &dev->stats_vq_elem, dev->stats_vq_offset);
         virtio_notify(&dev->vdev, dev->svq);
         return;
     }

     /* Stats are not supported.  Clear out any stale values that might
      * have been set by a more featureful guest kernel.
      */
     reset_stats(dev);
     complete_stats_request(dev);
 }

 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
 {
     VirtIOBalloon *dev = opaque;

     if (target > ram_size) {
         target = ram_size;
     }
     if (target) {
         dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
         virtio_notify_config(&dev->vdev);
     }
 }

 static void virtio_balloon_save(QEMUFile *f, void *opaque)
 {
     VirtIOBalloon *s = opaque;

     virtio_save(&s->vdev, f);

     qemu_put_be32(f, s->num_pages);
     qemu_put_be32(f, s->actual);
 }

 static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIOBalloon *s = opaque;

     if (version_id != 1)
         return -EINVAL;

     virtio_load(&s->vdev, f);

     s->num_pages = qemu_get_be32(f);
     s->actual = qemu_get_be32(f);
     return 0;
 }

 VirtIODevice *virtio_balloon_init(DeviceState *dev)
 {
     VirtIOBalloon *s;
     int ret;

     s = (VirtIOBalloon *)virtio_common_init("virtio-balloon",
                                             VIRTIO_ID_BALLOON,
                                             8, sizeof(VirtIOBalloon));

     s->vdev.get_config = virtio_balloon_get_config;
     s->vdev.set_config = virtio_balloon_set_config;
     s->vdev.get_features = virtio_balloon_get_features;

     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
                                    virtio_balloon_stat, s);
     if (ret < 0) {
         virtio_cleanup(&s->vdev);
         return NULL;
     }

     s->ivq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
     s->dvq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
     s->svq = virtio_add_queue(&s->vdev, 128, virtio_balloon_receive_stats);

     reset_stats(s);

     s->qdev = dev;
     register_savevm(dev, "virtio-balloon", -1, 1,
                     virtio_balloon_save, virtio_balloon_load, s);

     return &s->vdev;
 }

 void virtio_balloon_exit(VirtIODevice *vdev)
 {
     VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
     unregister_savevm(s->qdev, "virtio-balloon", s);
     virtio_cleanup(vdev);
 }
	/*
	* Virtio Balloon Device
	*
	* Copyright IBM, Corp. 2008
	* Copyright (C) 2011 Red Hat, Inc.
	* Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>
	*
	* Authors:
	* Anthony Liguori <aliguori@us.ibm.com>
	*
	* This work is licensed under the terms of the GNU GPL, version 2. See
	* the COPYING file in the top-level directory.
	*
	*/

	#include "iov.h"
	#include "qemu-common.h"
	#include "virtio.h"
	#include "pc.h"
	#include "cpu.h"
	#include "monitor.h"
	#include "balloon.h"
	#include "virtio-balloon.h"
	#include "kvm.h"
	#include "qlist.h"
	#include "qint.h"
	#include "qstring.h"

	#if defined(__linux__)
	#include <sys/mman.h>
	#endif

	/* Disable guest-provided stats by now (https://bugzilla.redhat.com/show_bug.cgi?id=623903) */
	#define ENABLE_GUEST_STATS 0


	typedef struct VirtIOBalloon
	{
	VirtIODevice vdev;
	VirtQueue ivq, dvq, *svq;
	uint32_t num_pages;
	uint32_t actual;
	uint64_t stats[VIRTIO_BALLOON_S_NR];
	VirtQueueElement stats_vq_elem;
	size_t stats_vq_offset;
	MonitorCompletion *stats_callback;
	void *stats_opaque_callback_data;
	DeviceState *qdev;
	} VirtIOBalloon;

	static VirtIOBalloon to_virtio_balloon(VirtIODevice vdev)
	{
	return (VirtIOBalloon *)vdev;
	}

	static void balloon_page(void *addr, int deflate)
	{
	#if defined(__linux__)
	if (!kvm_enabled() \|\| kvm_has_sync_mmu())
	qemu_madvise(addr, TARGET_PAGE_SIZE,
	deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
	#endif
	}

	/*
	* reset_stats - Mark all items in the stats array as unset
	*
	* This function needs to be called at device intialization and before
	* before updating to a set of newly-generated stats. This will ensure that no
	* stale values stick around in case the guest reports a subset of the supported
	* statistics.
	*/
	static inline void reset_stats(VirtIOBalloon *dev)
	{
	int i;
	for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
	}

	static void stat_put(QDict dict, const char label, uint64_t val)
	{
	if (val != -1)
	qdict_put(dict, label, qint_from_int(val));
	}

	static QObject get_stats_qobject(VirtIOBalloon dev)
	{
	QDict *dict = qdict_new();
	uint64_t actual = ram_size - ((uint64_t) dev->actual <<
	VIRTIO_BALLOON_PFN_SHIFT);

	stat_put(dict, "actual", actual);
	#if ENABLE_GUEST_STATS
	stat_put(dict, "mem_swapped_in", dev->stats[VIRTIO_BALLOON_S_SWAP_IN]);
	stat_put(dict, "mem_swapped_out", dev->stats[VIRTIO_BALLOON_S_SWAP_OUT]);
	stat_put(dict, "major_page_faults", dev->stats[VIRTIO_BALLOON_S_MAJFLT]);
	stat_put(dict, "minor_page_faults", dev->stats[VIRTIO_BALLOON_S_MINFLT]);
	stat_put(dict, "free_mem", dev->stats[VIRTIO_BALLOON_S_MEMFREE]);
	stat_put(dict, "total_mem", dev->stats[VIRTIO_BALLOON_S_MEMTOT]);
	#endif

	return QOBJECT(dict);
	}

	static void virtio_balloon_handle_output(VirtIODevice vdev, VirtQueue vq)
	{
	VirtIOBalloon *s = to_virtio_balloon(vdev);
	VirtQueueElement elem;

	while (virtqueue_pop(vq, &elem)) {
	size_t offset = 0;
	uint32_t pfn;

	while (iov_to_buf(elem.out_sg, elem.out_num, &pfn, offset, 4) == 4) {
	ram_addr_t pa;
	ram_addr_t addr;

	pa = (ram_addr_t)ldl_p(&pfn) << VIRTIO_BALLOON_PFN_SHIFT;
	offset += 4;

	addr = cpu_get_physical_page_desc(pa);
	if ((addr & ~TARGET_PAGE_MASK) != IO_MEM_RAM)
	continue;

	/* Using qemu_get_ram_ptr is bending the rules a bit, but
	should be OK because we only want a single page. */
	balloon_page(qemu_get_ram_ptr(addr), !!(vq == s->dvq));
	}

	virtqueue_push(vq, &elem, offset);
	virtio_notify(vdev, vq);
	}
	}

	static void complete_stats_request(VirtIOBalloon *vb)
	{
	QObject *stats;

	if (!vb->stats_opaque_callback_data)
	return;

	stats = get_stats_qobject(vb);
	vb->stats_callback(vb->stats_opaque_callback_data, stats);
	qobject_decref(stats);
	vb->stats_opaque_callback_data = NULL;
	vb->stats_callback = NULL;
	}

	static void virtio_balloon_receive_stats(VirtIODevice vdev, VirtQueue vq)
	{
	VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
	VirtQueueElement *elem = &s->stats_vq_elem;
	VirtIOBalloonStat stat;
	size_t offset = 0;

	if (!virtqueue_pop(vq, elem)) {
	return;
	}

	/* Initialize the stats to get rid of any stale values. This is only
	* needed to handle the case where a guest supports fewer stats than it
	* used to (ie. it has booted into an old kernel).
	*/
	reset_stats(s);

	while (iov_to_buf(elem->out_sg, elem->out_num, &stat, offset, sizeof(stat))
	== sizeof(stat)) {
	uint16_t tag = tswap16(stat.tag);
	uint64_t val = tswap64(stat.val);

	offset += sizeof(stat);
	if (tag < VIRTIO_BALLOON_S_NR)
	s->stats[tag] = val;
	}
	s->stats_vq_offset = offset;

	complete_stats_request(s);
	}

	static void virtio_balloon_get_config(VirtIODevice vdev, uint8_t config_data)
	{
	VirtIOBalloon *dev = to_virtio_balloon(vdev);
	struct virtio_balloon_config config;

	config.num_pages = cpu_to_le32(dev->num_pages);
	config.actual = cpu_to_le32(dev->actual);

	memcpy(config_data, &config, 8);
	}

	static void virtio_balloon_set_config(VirtIODevice *vdev,
	const uint8_t *config_data)
	{
	VirtIOBalloon *dev = to_virtio_balloon(vdev);
	struct virtio_balloon_config config;
	memcpy(&config, config_data, 8);
	dev->actual = le32_to_cpu(config.actual);
	}

	static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
	{
	f \|= (1 << VIRTIO_BALLOON_F_STATS_VQ);
	return f;
	}

	static void virtio_balloon_stat(void *opaque, MonitorCompletion cb,
	void *cb_data)
	{
	VirtIOBalloon *dev = opaque;

	/* For now, only allow one request at a time. This restriction can be
	* removed later by queueing callback and data pairs.
	*/
	if (dev->stats_callback != NULL) {
	return;
	}
	dev->stats_callback = cb;
	dev->stats_opaque_callback_data = cb_data;

	if (ENABLE_GUEST_STATS
	&& (dev->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ))) {
	virtqueue_push(dev->svq, &dev->stats_vq_elem, dev->stats_vq_offset);
	virtio_notify(&dev->vdev, dev->svq);
	return;
	}

	/* Stats are not supported. Clear out any stale values that might
	* have been set by a more featureful guest kernel.
	*/
	reset_stats(dev);
	complete_stats_request(dev);
	}

	static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
	{
	VirtIOBalloon *dev = opaque;

	if (target > ram_size) {
	target = ram_size;
	}
	if (target) {
	dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
	virtio_notify_config(&dev->vdev);
	}
	}

	static void virtio_balloon_save(QEMUFile f, void opaque)
	{
	VirtIOBalloon *s = opaque;

	virtio_save(&s->vdev, f);

	qemu_put_be32(f, s->num_pages);
	qemu_put_be32(f, s->actual);
	}

	static int virtio_balloon_load(QEMUFile f, void opaque, int version_id)
	{
	VirtIOBalloon *s = opaque;

	if (version_id != 1)
	return -EINVAL;

	virtio_load(&s->vdev, f);

	s->num_pages = qemu_get_be32(f);
	s->actual = qemu_get_be32(f);
	return 0;
	}

	VirtIODevice virtio_balloon_init(DeviceState dev)
	{
	VirtIOBalloon *s;
	int ret;

	s = (VirtIOBalloon *)virtio_common_init("virtio-balloon",
	VIRTIO_ID_BALLOON,
	8, sizeof(VirtIOBalloon));

	s->vdev.get_config = virtio_balloon_get_config;
	s->vdev.set_config = virtio_balloon_set_config;
	s->vdev.get_features = virtio_balloon_get_features;

	ret = qemu_add_balloon_handler(virtio_balloon_to_target,
	virtio_balloon_stat, s);
	if (ret < 0) {
	virtio_cleanup(&s->vdev);
	return NULL;
	}

	s->ivq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
	s->dvq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
	s->svq = virtio_add_queue(&s->vdev, 128, virtio_balloon_receive_stats);

	reset_stats(s);

	s->qdev = dev;
	register_savevm(dev, "virtio-balloon", -1, 1,
	virtio_balloon_save, virtio_balloon_load, s);

	return &s->vdev;
	}

	void virtio_balloon_exit(VirtIODevice *vdev)
	{
	VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
	unregister_savevm(s->qdev, "virtio-balloon", s);
	virtio_cleanup(vdev);
	}