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qemu/hw/virtio-balloon.c

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/*
* 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);
qemu_remove_balloon_handler(s);
unregister_savevm(s->qdev, "virtio-balloon", s);
virtio_cleanup(vdev);
}
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