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xemu/hw/virtio/virtio-balloon.c
Alexander Duyck 91b867191d virtio-balloon: Provide an interface for free page reporting 
Add support for free page reporting. The idea is to function very similar
to how the balloon works in that we basically end up madvising the page as
not being used. However we don't really need to bother with any deflate
type logic since the page will be faulted back into the guest when it is
read or written to.

This provides a new way of letting the guest proactively report free
pages to the hypervisor, so the hypervisor can reuse them. In contrast to
inflate/deflate that is triggered via the hypervisor explicitly.

Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Message-Id: <20200527041407.12700.73735.stgit@localhost.localdomain>
2020-06-09 14:18:04 -04:00

1063 lines
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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 "qemu/osdep.h"
#include "qemu/iov.h"
#include "qemu/module.h"
#include "qemu/timer.h"
#include "hw/virtio/virtio.h"
#include "hw/mem/pc-dimm.h"
#include "hw/qdev-properties.h"
#include "sysemu/balloon.h"
#include "hw/virtio/virtio-balloon.h"
#include "exec/address-spaces.h"
#include "qapi/error.h"
#include "qapi/qapi-events-misc.h"
#include "qapi/visitor.h"
#include "trace.h"
#include "qemu/error-report.h"
#include "migration/misc.h"
#include "hw/virtio/virtio-bus.h"
#include "hw/virtio/virtio-access.h"
#define BALLOON_PAGE_SIZE (1 << VIRTIO_BALLOON_PFN_SHIFT)
typedef struct PartiallyBalloonedPage {
ram_addr_t base_gpa;
unsigned long *bitmap;
} PartiallyBalloonedPage;
static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
{
if (!pbp->bitmap) {
return;
}
g_free(pbp->bitmap);
pbp->bitmap = NULL;
}
static void virtio_balloon_pbp_alloc(PartiallyBalloonedPage *pbp,
ram_addr_t base_gpa,
long subpages)
{
pbp->base_gpa = base_gpa;
pbp->bitmap = bitmap_new(subpages);
}
static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
ram_addr_t base_gpa)
{
return pbp->base_gpa == base_gpa;
}
static void balloon_inflate_page(VirtIOBalloon *balloon,
MemoryRegion *mr, hwaddr mr_offset,
PartiallyBalloonedPage *pbp)
{
void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
RAMBlock *rb;
size_t rb_page_size;
int subpages;
/* XXX is there a better way to get to the RAMBlock than via a
* host address? */
rb = qemu_ram_block_from_host(addr, false, &rb_offset);
rb_page_size = qemu_ram_pagesize(rb);
if (rb_page_size == BALLOON_PAGE_SIZE) {
/* Easy case */
ram_block_discard_range(rb, rb_offset, rb_page_size);
/* We ignore errors from ram_block_discard_range(), because it
* has already reported them, and failing to discard a balloon
* page is not fatal */
return;
}
/* Hard case
*
* We've put a piece of a larger host page into the balloon - we
* need to keep track until we have a whole host page to
* discard
*/
warn_report_once(
"Balloon used with backing page size > 4kiB, this may not be reliable");
rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
subpages = rb_page_size / BALLOON_PAGE_SIZE;
base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
(rb_offset - rb_aligned_offset);
if (pbp->bitmap && !virtio_balloon_pbp_matches(pbp, base_gpa)) {
/* We've partially ballooned part of a host page, but now
* we're trying to balloon part of a different one. Too hard,
* give up on the old partial page */
virtio_balloon_pbp_free(pbp);
}
if (!pbp->bitmap) {
virtio_balloon_pbp_alloc(pbp, base_gpa, subpages);
}
set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
pbp->bitmap);
if (bitmap_full(pbp->bitmap, subpages)) {
/* We've accumulated a full host page, we can actually discard
* it now */
ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
/* We ignore errors from ram_block_discard_range(), because it
* has already reported them, and failing to discard a balloon
* page is not fatal */
virtio_balloon_pbp_free(pbp);
}
}
static void balloon_deflate_page(VirtIOBalloon *balloon,
MemoryRegion *mr, hwaddr mr_offset)
{
void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
ram_addr_t rb_offset;
RAMBlock *rb;
size_t rb_page_size;
void *host_addr;
int ret;
/* XXX is there a better way to get to the RAMBlock than via a
* host address? */
rb = qemu_ram_block_from_host(addr, false, &rb_offset);
rb_page_size = qemu_ram_pagesize(rb);
host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
/* When a page is deflated, we hint the whole host page it lives
* on, since we can't do anything smaller */
ret = qemu_madvise(host_addr, rb_page_size, QEMU_MADV_WILLNEED);
if (ret != 0) {
warn_report("Couldn't MADV_WILLNEED on balloon deflate: %s",
strerror(errno));
/* Otherwise ignore, failing to page hint shouldn't be fatal */
}
}
static const char *balloon_stat_names[] = {
[VIRTIO_BALLOON_S_SWAP_IN] = "stat-swap-in",
[VIRTIO_BALLOON_S_SWAP_OUT] = "stat-swap-out",
[VIRTIO_BALLOON_S_MAJFLT] = "stat-major-faults",
[VIRTIO_BALLOON_S_MINFLT] = "stat-minor-faults",
[VIRTIO_BALLOON_S_MEMFREE] = "stat-free-memory",
[VIRTIO_BALLOON_S_MEMTOT] = "stat-total-memory",
[VIRTIO_BALLOON_S_AVAIL] = "stat-available-memory",
[VIRTIO_BALLOON_S_CACHES] = "stat-disk-caches",
[VIRTIO_BALLOON_S_HTLB_PGALLOC] = "stat-htlb-pgalloc",
[VIRTIO_BALLOON_S_HTLB_PGFAIL] = "stat-htlb-pgfail",
[VIRTIO_BALLOON_S_NR] = NULL
};
/*
* reset_stats - Mark all items in the stats array as unset
*
* This function needs to be called at device initialization and 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 bool balloon_stats_supported(const VirtIOBalloon *s)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s);
return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_STATS_VQ);
}
static bool balloon_stats_enabled(const VirtIOBalloon *s)
{
return s->stats_poll_interval > 0;
}
static void balloon_stats_destroy_timer(VirtIOBalloon *s)
{
if (balloon_stats_enabled(s)) {
timer_del(s->stats_timer);
timer_free(s->stats_timer);
s->stats_timer = NULL;
s->stats_poll_interval = 0;
}
}
static void balloon_stats_change_timer(VirtIOBalloon *s, int64_t secs)
{
timer_mod(s->stats_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + secs * 1000);
}
static void balloon_stats_poll_cb(void *opaque)
{
VirtIOBalloon *s = opaque;
VirtIODevice *vdev = VIRTIO_DEVICE(s);
if (s->stats_vq_elem == NULL || !balloon_stats_supported(s)) {
/* re-schedule */
balloon_stats_change_timer(s, s->stats_poll_interval);
return;
}
virtqueue_push(s->svq, s->stats_vq_elem, s->stats_vq_offset);
virtio_notify(vdev, s->svq);
g_free(s->stats_vq_elem);
s->stats_vq_elem = NULL;
}
static void balloon_stats_get_all(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
Error *err = NULL;
VirtIOBalloon *s = opaque;
int i;
visit_start_struct(v, name, NULL, 0, &err);
if (err) {
goto out;
}
visit_type_int(v, "last-update", &s->stats_last_update, &err);
if (err) {
goto out_end;
}
visit_start_struct(v, "stats", NULL, 0, &err);
if (err) {
goto out_end;
}
for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
visit_type_uint64(v, balloon_stat_names[i], &s->stats[i], &err);
if (err) {
goto out_nested;
}
}
visit_check_struct(v, &err);
out_nested:
visit_end_struct(v, NULL);
if (!err) {
visit_check_struct(v, &err);
}
out_end:
visit_end_struct(v, NULL);
out:
error_propagate(errp, err);
}
static void balloon_stats_get_poll_interval(Object *obj, Visitor *v,
const char *name, void *opaque,
Error **errp)
{
VirtIOBalloon *s = opaque;
visit_type_int(v, name, &s->stats_poll_interval, errp);
}
static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
const char *name, void *opaque,
Error **errp)
{
VirtIOBalloon *s = opaque;
Error *local_err = NULL;
int64_t value;
visit_type_int(v, name, &value, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
if (value < 0) {
error_setg(errp, "timer value must be greater than zero");
return;
}
if (value > UINT32_MAX) {
error_setg(errp, "timer value is too big");
return;
}
if (value == s->stats_poll_interval) {
return;
}
if (value == 0) {
/* timer=0 disables the timer */
balloon_stats_destroy_timer(s);
return;
}
if (balloon_stats_enabled(s)) {
/* timer interval change */
s->stats_poll_interval = value;
balloon_stats_change_timer(s, value);
return;
}
/* create a new timer */
g_assert(s->stats_timer == NULL);
s->stats_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, balloon_stats_poll_cb, s);
s->stats_poll_interval = value;
balloon_stats_change_timer(s, 0);
}
static void virtio_balloon_handle_report(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
VirtQueueElement *elem;
while ((elem = virtqueue_pop(vq, sizeof(VirtQueueElement)))) {
unsigned int i;
/*
* When we discard the page it has the effect of removing the page
* from the hypervisor itself and causing it to be zeroed when it
* is returned to us. So we must not discard the page if it is
* accessible by another device or process, or if the guest is
* expecting it to retain a non-zero value.
*/
if (qemu_balloon_is_inhibited() || dev->poison_val) {
goto skip_element;
}
for (i = 0; i < elem->in_num; i++) {
void *addr = elem->in_sg[i].iov_base;
size_t size = elem->in_sg[i].iov_len;
ram_addr_t ram_offset;
RAMBlock *rb;
/*
* There is no need to check the memory section to see if
* it is ram/readonly/romd like there is for handle_output
* below. If the region is not meant to be written to then
* address_space_map will have allocated a bounce buffer
* and it will be freed in address_space_unmap and trigger
* and unassigned_mem_write before failing to copy over the
* buffer. If more than one bad descriptor is provided it
* will return NULL after the first bounce buffer and fail
* to map any resources.
*/
rb = qemu_ram_block_from_host(addr, false, &ram_offset);
if (!rb) {
trace_virtio_balloon_bad_addr(elem->in_addr[i]);
continue;
}
/*
* For now we will simply ignore unaligned memory regions, or
* regions that overrun the end of the RAMBlock.
*/
if (!QEMU_IS_ALIGNED(ram_offset | size, qemu_ram_pagesize(rb)) ||
(ram_offset + size) > qemu_ram_get_used_length(rb)) {
continue;
}
ram_block_discard_range(rb, ram_offset, size);
}
skip_element:
virtqueue_push(vq, elem, 0);
virtio_notify(vdev, vq);
g_free(elem);
}
}
static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
VirtQueueElement *elem;
MemoryRegionSection section;
for (;;) {
PartiallyBalloonedPage pbp = {};
size_t offset = 0;
uint32_t pfn;
elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
if (!elem) {
break;
}
while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
unsigned int p = virtio_ldl_p(vdev, &pfn);
hwaddr pa;
pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
offset += 4;
section = memory_region_find(get_system_memory(), pa,
BALLOON_PAGE_SIZE);
if (!section.mr) {
trace_virtio_balloon_bad_addr(pa);
continue;
}
if (!memory_region_is_ram(section.mr) ||
memory_region_is_rom(section.mr) ||
memory_region_is_romd(section.mr)) {
trace_virtio_balloon_bad_addr(pa);
memory_region_unref(section.mr);
continue;
}
trace_virtio_balloon_handle_output(memory_region_name(section.mr),
pa);
if (!qemu_balloon_is_inhibited()) {
if (vq == s->ivq) {
balloon_inflate_page(s, section.mr,
section.offset_within_region, &pbp);
} else if (vq == s->dvq) {
balloon_deflate_page(s, section.mr, section.offset_within_region);
} else {
g_assert_not_reached();
}
}
memory_region_unref(section.mr);
}
virtqueue_push(vq, elem, offset);
virtio_notify(vdev, vq);
g_free(elem);
virtio_balloon_pbp_free(&pbp);
}
}
static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
VirtQueueElement *elem;
VirtIOBalloonStat stat;
size_t offset = 0;
qemu_timeval tv;
elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
if (!elem) {
goto out;
}
if (s->stats_vq_elem != NULL) {
/* This should never happen if the driver follows the spec. */
virtqueue_push(vq, s->stats_vq_elem, 0);
virtio_notify(vdev, vq);
g_free(s->stats_vq_elem);
}
s->stats_vq_elem = elem;
/* 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, offset, &stat, sizeof(stat))
== sizeof(stat)) {
uint16_t tag = virtio_tswap16(vdev, stat.tag);
uint64_t val = virtio_tswap64(vdev, stat.val);
offset += sizeof(stat);
if (tag < VIRTIO_BALLOON_S_NR)
s->stats[tag] = val;
}
s->stats_vq_offset = offset;
if (qemu_gettimeofday(&tv) < 0) {
warn_report("%s: failed to get time of day", __func__);
goto out;
}
s->stats_last_update = tv.tv_sec;
out:
if (balloon_stats_enabled(s)) {
balloon_stats_change_timer(s, s->stats_poll_interval);
}
}
static void virtio_balloon_handle_free_page_vq(VirtIODevice *vdev,
VirtQueue *vq)
{
VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
qemu_bh_schedule(s->free_page_bh);
}
static bool get_free_page_hints(VirtIOBalloon *dev)
{
VirtQueueElement *elem;
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtQueue *vq = dev->free_page_vq;
bool ret = true;
while (dev->block_iothread) {
qemu_cond_wait(&dev->free_page_cond, &dev->free_page_lock);
}
elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
if (!elem) {
return false;
}
if (elem->out_num) {
uint32_t id;
size_t size = iov_to_buf(elem->out_sg, elem->out_num, 0,
&id, sizeof(id));
virtio_tswap32s(vdev, &id);
if (unlikely(size != sizeof(id))) {
virtio_error(vdev, "received an incorrect cmd id");
ret = false;
goto out;
}
if (id == dev->free_page_report_cmd_id) {
dev->free_page_report_status = FREE_PAGE_REPORT_S_START;
} else {
/*
* Stop the optimization only when it has started. This
* avoids a stale stop sign for the previous command.
*/
if (dev->free_page_report_status == FREE_PAGE_REPORT_S_START) {
dev->free_page_report_status = FREE_PAGE_REPORT_S_STOP;
}
}
}
if (elem->in_num) {
if (dev->free_page_report_status == FREE_PAGE_REPORT_S_START) {
qemu_guest_free_page_hint(elem->in_sg[0].iov_base,
elem->in_sg[0].iov_len);
}
}
out:
virtqueue_push(vq, elem, 1);
g_free(elem);
return ret;
}
static void virtio_ballloon_get_free_page_hints(void *opaque)
{
VirtIOBalloon *dev = opaque;
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtQueue *vq = dev->free_page_vq;
bool continue_to_get_hints;
do {
qemu_mutex_lock(&dev->free_page_lock);
virtio_queue_set_notification(vq, 0);
continue_to_get_hints = get_free_page_hints(dev);
qemu_mutex_unlock(&dev->free_page_lock);
virtio_notify(vdev, vq);
/*
* Start to poll the vq once the reporting started. Otherwise, continue
* only when there are entries on the vq, which need to be given back.
*/
} while (continue_to_get_hints ||
dev->free_page_report_status == FREE_PAGE_REPORT_S_START);
virtio_queue_set_notification(vq, 1);
}
static bool virtio_balloon_free_page_support(void *opaque)
{
VirtIOBalloon *s = opaque;
VirtIODevice *vdev = VIRTIO_DEVICE(s);
return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT);
}
static void virtio_balloon_free_page_start(VirtIOBalloon *s)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s);
/* For the stop and copy phase, we don't need to start the optimization */
if (!vdev->vm_running) {
return;
}
if (s->free_page_report_cmd_id == UINT_MAX) {
s->free_page_report_cmd_id =
VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN;
} else {
s->free_page_report_cmd_id++;
}
s->free_page_report_status = FREE_PAGE_REPORT_S_REQUESTED;
virtio_notify_config(vdev);
}
static void virtio_balloon_free_page_stop(VirtIOBalloon *s)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s);
if (s->free_page_report_status != FREE_PAGE_REPORT_S_STOP) {
/*
* The lock also guarantees us that the
* virtio_ballloon_get_free_page_hints exits after the
* free_page_report_status is set to S_STOP.
*/
qemu_mutex_lock(&s->free_page_lock);
/*
* The guest hasn't done the reporting, so host sends a notification
* to the guest to actively stop the reporting.
*/
s->free_page_report_status = FREE_PAGE_REPORT_S_STOP;
qemu_mutex_unlock(&s->free_page_lock);
virtio_notify_config(vdev);
}
}
static void virtio_balloon_free_page_done(VirtIOBalloon *s)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s);
s->free_page_report_status = FREE_PAGE_REPORT_S_DONE;
virtio_notify_config(vdev);
}
static int
virtio_balloon_free_page_report_notify(NotifierWithReturn *n, void *data)
{
VirtIOBalloon *dev = container_of(n, VirtIOBalloon,
free_page_report_notify);
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
PrecopyNotifyData *pnd = data;
if (!virtio_balloon_free_page_support(dev)) {
/*
* This is an optimization provided to migration, so just return 0 to
* have the normal migration process not affected when this feature is
* not supported.
*/
return 0;
}
switch (pnd->reason) {
case PRECOPY_NOTIFY_SETUP:
precopy_enable_free_page_optimization();
break;
case PRECOPY_NOTIFY_COMPLETE:
case PRECOPY_NOTIFY_CLEANUP:
case PRECOPY_NOTIFY_BEFORE_BITMAP_SYNC:
virtio_balloon_free_page_stop(dev);
break;
case PRECOPY_NOTIFY_AFTER_BITMAP_SYNC:
if (vdev->vm_running) {
virtio_balloon_free_page_start(dev);
} else {
virtio_balloon_free_page_done(dev);
}
break;
default:
virtio_error(vdev, "%s: %d reason unknown", __func__, pnd->reason);
}
return 0;
}
static size_t virtio_balloon_config_size(VirtIOBalloon *s)
{
uint64_t features = s->host_features;
if (s->qemu_4_0_config_size) {
return sizeof(struct virtio_balloon_config);
}
if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON)) {
return sizeof(struct virtio_balloon_config);
}
if (virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
return offsetof(struct virtio_balloon_config, poison_val);
}
return offsetof(struct virtio_balloon_config, free_page_report_cmd_id);
}
static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
{
VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
struct virtio_balloon_config config = {};
config.num_pages = cpu_to_le32(dev->num_pages);
config.actual = cpu_to_le32(dev->actual);
config.poison_val = cpu_to_le32(dev->poison_val);
if (dev->free_page_report_status == FREE_PAGE_REPORT_S_REQUESTED) {
config.free_page_report_cmd_id =
cpu_to_le32(dev->free_page_report_cmd_id);
} else if (dev->free_page_report_status == FREE_PAGE_REPORT_S_STOP) {
config.free_page_report_cmd_id =
cpu_to_le32(VIRTIO_BALLOON_CMD_ID_STOP);
} else if (dev->free_page_report_status == FREE_PAGE_REPORT_S_DONE) {
config.free_page_report_cmd_id =
cpu_to_le32(VIRTIO_BALLOON_CMD_ID_DONE);
}
trace_virtio_balloon_get_config(config.num_pages, config.actual);
memcpy(config_data, &config, virtio_balloon_config_size(dev));
}
static int build_dimm_list(Object *obj, void *opaque)
{
GSList **list = opaque;
if (object_dynamic_cast(obj, TYPE_PC_DIMM)) {
DeviceState *dev = DEVICE(obj);
if (dev->realized) { /* only realized DIMMs matter */
*list = g_slist_prepend(*list, dev);
}
}
object_child_foreach(obj, build_dimm_list, opaque);
return 0;
}
static ram_addr_t get_current_ram_size(void)
{
GSList *list = NULL, *item;
ram_addr_t size = ram_size;
build_dimm_list(qdev_get_machine(), &list);
for (item = list; item; item = g_slist_next(item)) {
Object *obj = OBJECT(item->data);
if (!strcmp(object_get_typename(obj), TYPE_PC_DIMM)) {
size += object_property_get_int(obj, PC_DIMM_SIZE_PROP,
&error_abort);
}
}
g_slist_free(list);
return size;
}
static bool virtio_balloon_page_poison_support(void *opaque)
{
VirtIOBalloon *s = opaque;
VirtIODevice *vdev = VIRTIO_DEVICE(s);
return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
}
static void virtio_balloon_set_config(VirtIODevice *vdev,
const uint8_t *config_data)
{
VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
struct virtio_balloon_config config;
uint32_t oldactual = dev->actual;
ram_addr_t vm_ram_size = get_current_ram_size();
memcpy(&config, config_data, virtio_balloon_config_size(dev));
dev->actual = le32_to_cpu(config.actual);
if (dev->actual != oldactual) {
qapi_event_send_balloon_change(vm_ram_size -
((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT));
}
dev->poison_val = 0;
if (virtio_balloon_page_poison_support(dev)) {
dev->poison_val = le32_to_cpu(config.poison_val);
}
trace_virtio_balloon_set_config(dev->actual, oldactual);
}
static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f,
Error **errp)
{
VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
f |= dev->host_features;
virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ);
return f;
}
static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
{
VirtIOBalloon *dev = opaque;
info->actual = get_current_ram_size() - ((uint64_t) dev->actual <<
VIRTIO_BALLOON_PFN_SHIFT);
}
static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
{
VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
ram_addr_t vm_ram_size = get_current_ram_size();
if (target > vm_ram_size) {
target = vm_ram_size;
}
if (target) {
dev->num_pages = (vm_ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
virtio_notify_config(vdev);
}
trace_virtio_balloon_to_target(target, dev->num_pages);
}
static int virtio_balloon_post_load_device(void *opaque, int version_id)
{
VirtIOBalloon *s = VIRTIO_BALLOON(opaque);
if (balloon_stats_enabled(s)) {
balloon_stats_change_timer(s, s->stats_poll_interval);
}
return 0;
}
static const VMStateDescription vmstate_virtio_balloon_free_page_report = {
.name = "virtio-balloon-device/free-page-report",
.version_id = 1,
.minimum_version_id = 1,
.needed = virtio_balloon_free_page_support,
.fields = (VMStateField[]) {
VMSTATE_UINT32(free_page_report_cmd_id, VirtIOBalloon),
VMSTATE_UINT32(free_page_report_status, VirtIOBalloon),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_balloon_page_poison = {
.name = "vitio-balloon-device/page-poison",
.version_id = 1,
.minimum_version_id = 1,
.needed = virtio_balloon_page_poison_support,
.fields = (VMStateField[]) {
VMSTATE_UINT32(poison_val, VirtIOBalloon),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_balloon_device = {
.name = "virtio-balloon-device",
.version_id = 1,
.minimum_version_id = 1,
.post_load = virtio_balloon_post_load_device,
.fields = (VMStateField[]) {
VMSTATE_UINT32(num_pages, VirtIOBalloon),
VMSTATE_UINT32(actual, VirtIOBalloon),
VMSTATE_END_OF_LIST()
},
.subsections = (const VMStateDescription * []) {
&vmstate_virtio_balloon_free_page_report,
&vmstate_virtio_balloon_page_poison,
NULL
}
};
static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIOBalloon *s = VIRTIO_BALLOON(dev);
int ret;
virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON,
virtio_balloon_config_size(s));
ret = qemu_add_balloon_handler(virtio_balloon_to_target,
virtio_balloon_stat, s);
if (ret < 0) {
error_setg(errp, "Only one balloon device is supported");
virtio_cleanup(vdev);
return;
}
if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_FREE_PAGE_HINT) &&
!s->iothread) {
error_setg(errp, "'free-page-hint' requires 'iothread' to be set");
virtio_cleanup(vdev);
return;
}
s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
if (virtio_has_feature(s->host_features,
VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
s->free_page_vq = virtio_add_queue(vdev, VIRTQUEUE_MAX_SIZE,
virtio_balloon_handle_free_page_vq);
precopy_add_notifier(&s->free_page_report_notify);
object_ref(OBJECT(s->iothread));
s->free_page_bh = aio_bh_new(iothread_get_aio_context(s->iothread),
virtio_ballloon_get_free_page_hints, s);
}
if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_REPORTING)) {
s->reporting_vq = virtio_add_queue(vdev, 32,
virtio_balloon_handle_report);
}
reset_stats(s);
}
static void virtio_balloon_device_unrealize(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIOBalloon *s = VIRTIO_BALLOON(dev);
if (s->free_page_bh) {
qemu_bh_delete(s->free_page_bh);
object_unref(OBJECT(s->iothread));
virtio_balloon_free_page_stop(s);
precopy_remove_notifier(&s->free_page_report_notify);
}
balloon_stats_destroy_timer(s);
qemu_remove_balloon_handler(s);
virtio_delete_queue(s->ivq);
virtio_delete_queue(s->dvq);
virtio_delete_queue(s->svq);
if (s->free_page_vq) {
virtio_delete_queue(s->free_page_vq);
}
if (s->reporting_vq) {
virtio_delete_queue(s->reporting_vq);
}
virtio_cleanup(vdev);
}
static void virtio_balloon_device_reset(VirtIODevice *vdev)
{
VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
if (virtio_balloon_free_page_support(s)) {
virtio_balloon_free_page_stop(s);
}
if (s->stats_vq_elem != NULL) {
virtqueue_unpop(s->svq, s->stats_vq_elem, 0);
g_free(s->stats_vq_elem);
s->stats_vq_elem = NULL;
}
s->poison_val = 0;
}
static void virtio_balloon_set_status(VirtIODevice *vdev, uint8_t status)
{
VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
if (!s->stats_vq_elem && vdev->vm_running &&
(status & VIRTIO_CONFIG_S_DRIVER_OK) && virtqueue_rewind(s->svq, 1)) {
/* poll stats queue for the element we have discarded when the VM
* was stopped */
virtio_balloon_receive_stats(vdev, s->svq);
}
if (virtio_balloon_free_page_support(s)) {
/*
* The VM is woken up and the iothread was blocked, so signal it to
* continue.
*/
if (vdev->vm_running && s->block_iothread) {
qemu_mutex_lock(&s->free_page_lock);
s->block_iothread = false;
qemu_cond_signal(&s->free_page_cond);
qemu_mutex_unlock(&s->free_page_lock);
}
/* The VM is stopped, block the iothread. */
if (!vdev->vm_running) {
qemu_mutex_lock(&s->free_page_lock);
s->block_iothread = true;
qemu_mutex_unlock(&s->free_page_lock);
}
}
}
static void virtio_balloon_instance_init(Object *obj)
{
VirtIOBalloon *s = VIRTIO_BALLOON(obj);
qemu_mutex_init(&s->free_page_lock);
qemu_cond_init(&s->free_page_cond);
s->free_page_report_cmd_id = VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN;
s->free_page_report_notify.notify = virtio_balloon_free_page_report_notify;
object_property_add(obj, "guest-stats", "guest statistics",
balloon_stats_get_all, NULL, NULL, s);
object_property_add(obj, "guest-stats-polling-interval", "int",
balloon_stats_get_poll_interval,
balloon_stats_set_poll_interval,
NULL, s);
}
static const VMStateDescription vmstate_virtio_balloon = {
.name = "virtio-balloon",
.minimum_version_id = 1,
.version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_VIRTIO_DEVICE,
VMSTATE_END_OF_LIST()
},
};
static Property virtio_balloon_properties[] = {
DEFINE_PROP_BIT("deflate-on-oom", VirtIOBalloon, host_features,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false),
DEFINE_PROP_BIT("free-page-hint", VirtIOBalloon, host_features,
VIRTIO_BALLOON_F_FREE_PAGE_HINT, false),
DEFINE_PROP_BIT("page-poison", VirtIOBalloon, host_features,
VIRTIO_BALLOON_F_PAGE_POISON, true),
DEFINE_PROP_BIT("free-page-reporting", VirtIOBalloon, host_features,
VIRTIO_BALLOON_F_REPORTING, false),
/* QEMU 4.0 accidentally changed the config size even when free-page-hint
* is disabled, resulting in QEMU 3.1 migration incompatibility. This
* property retains this quirk for QEMU 4.1 machine types.
*/
DEFINE_PROP_BOOL("qemu-4-0-config-size", VirtIOBalloon,
qemu_4_0_config_size, false),
DEFINE_PROP_LINK("iothread", VirtIOBalloon, iothread, TYPE_IOTHREAD,
IOThread *),
DEFINE_PROP_END_OF_LIST(),
};
static void virtio_balloon_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
device_class_set_props(dc, virtio_balloon_properties);
dc->vmsd = &vmstate_virtio_balloon;
set_bit(DEVICE_CATEGORY_MISC, dc->categories);
vdc->realize = virtio_balloon_device_realize;
vdc->unrealize = virtio_balloon_device_unrealize;
vdc->reset = virtio_balloon_device_reset;
vdc->get_config = virtio_balloon_get_config;
vdc->set_config = virtio_balloon_set_config;
vdc->get_features = virtio_balloon_get_features;
vdc->set_status = virtio_balloon_set_status;
vdc->vmsd = &vmstate_virtio_balloon_device;
}
static const TypeInfo virtio_balloon_info = {
.name = TYPE_VIRTIO_BALLOON,
.parent = TYPE_VIRTIO_DEVICE,
.instance_size = sizeof(VirtIOBalloon),
.instance_init = virtio_balloon_instance_init,
.class_init = virtio_balloon_class_init,
};
static void virtio_register_types(void)
{
type_register_static(&virtio_balloon_info);
}
type_init(virtio_register_types)
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