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qemu/hw/virtio/virtio-balloon.c
Alexander Bulekov f63192b054 hw: replace most qemu_bh_new calls with qemu_bh_new_guarded 
This protects devices from bh->mmio reentrancy issues.

Thanks: Thomas Huth <thuth@redhat.com> for diagnosing OS X test failure.
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20230427211013.2994127-5-alxndr@bu.edu>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2023-04-28 11:31:54 +02:00

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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 "qemu/madvise.h"
#include "hw/virtio/virtio.h"
#include "hw/mem/pc-dimm.h"
#include "hw/qdev-properties.h"
#include "hw/boards.h"
#include "sysemu/balloon.h"
#include "hw/virtio/virtio-balloon.h"
#include "exec/address-spaces.h"
#include "qapi/error.h"
#include "qapi/qapi-events-machine.h"
#include "qapi/visitor.h"
#include "trace.h"
#include "qemu/error-report.h"
#include "migration/misc.h"
#include "migration/migration.h"
#include "migration/options.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 bool virtio_balloon_inhibited(void)
{
/*
* Postcopy cannot deal with concurrent discards,
* so it's special, as well as background snapshots.
*/
return ram_block_discard_is_disabled() || migration_in_incoming_postcopy() ||
migration_in_bg_snapshot();
}
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_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, 0);
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)
{
VirtIOBalloon *s = VIRTIO_BALLOON(obj);
bool ok = false;
int i;
if (!visit_start_struct(v, name, NULL, 0, errp)) {
return;
}
if (!visit_type_int(v, "last-update", &s->stats_last_update, errp)) {
goto out_end;
}
if (!visit_start_struct(v, "stats", NULL, 0, errp)) {
goto out_end;
}
for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
if (!visit_type_uint64(v, balloon_stat_names[i], &s->stats[i], errp)) {
goto out_nested;
}
}
ok = visit_check_struct(v, errp);
out_nested:
visit_end_struct(v, NULL);
if (ok) {
visit_check_struct(v, errp);
}
out_end:
visit_end_struct(v, NULL);
}
static void balloon_stats_get_poll_interval(Object *obj, Visitor *v,
const char *name, void *opaque,
Error **errp)
{
VirtIOBalloon *s = VIRTIO_BALLOON(obj);
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 = VIRTIO_BALLOON(obj);
int64_t value;
if (!visit_type_int(v, name, &value, errp)) {
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 (virtio_balloon_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 (!virtio_balloon_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, 0);
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;
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;
s->stats_last_update = g_get_real_time() / G_USEC_PER_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;
int i;
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 (dev->free_page_hint_status == FREE_PAGE_HINT_S_REQUESTED &&
id == dev->free_page_hint_cmd_id) {
dev->free_page_hint_status = FREE_PAGE_HINT_S_START;
} else if (dev->free_page_hint_status == FREE_PAGE_HINT_S_START) {
/*
* Stop the optimization only when it has started. This
* avoids a stale stop sign for the previous command.
*/
dev->free_page_hint_status = FREE_PAGE_HINT_S_STOP;
}
}
if (elem->in_num && dev->free_page_hint_status == FREE_PAGE_HINT_S_START) {
for (i = 0; i < elem->in_num; i++) {
qemu_guest_free_page_hint(elem->in_sg[i].iov_base,
elem->in_sg[i].iov_len);
}
}
out:
virtqueue_push(vq, elem, 0);
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 hinting 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_hint_status == FREE_PAGE_HINT_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);
qemu_mutex_lock(&s->free_page_lock);
if (s->free_page_hint_cmd_id == UINT_MAX) {
s->free_page_hint_cmd_id = VIRTIO_BALLOON_FREE_PAGE_HINT_CMD_ID_MIN;
} else {
s->free_page_hint_cmd_id++;
}
s->free_page_hint_status = FREE_PAGE_HINT_S_REQUESTED;
qemu_mutex_unlock(&s->free_page_lock);
virtio_notify_config(vdev);
}
static void virtio_balloon_free_page_stop(VirtIOBalloon *s)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s);
if (s->free_page_hint_status != FREE_PAGE_HINT_S_STOP) {
/*
* The lock also guarantees us that the
* virtio_ballloon_get_free_page_hints exits after the
* free_page_hint_status is set to S_STOP.
*/
qemu_mutex_lock(&s->free_page_lock);
/*
* The guest isn't done hinting, so send a notification
* to the guest to actively stop the hinting.
*/
s->free_page_hint_status = FREE_PAGE_HINT_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);
if (s->free_page_hint_status != FREE_PAGE_HINT_S_DONE) {
/* See virtio_balloon_free_page_stop() */
qemu_mutex_lock(&s->free_page_lock);
s->free_page_hint_status = FREE_PAGE_HINT_S_DONE;
qemu_mutex_unlock(&s->free_page_lock);
virtio_notify_config(vdev);
}
}
static int
virtio_balloon_free_page_hint_notify(NotifierWithReturn *n, void *data)
{
VirtIOBalloon *dev = container_of(n, VirtIOBalloon, free_page_hint_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;
}
/*
* Pages hinted via qemu_guest_free_page_hint() are cleared from the dirty
* bitmap and will not get migrated, especially also not when the postcopy
* destination starts using them and requests migration from the source; the
* faulting thread will stall until postcopy migration finishes and
* all threads are woken up. Let's not start free page hinting if postcopy
* is possible.
*/
if (migrate_postcopy_ram()) {
return 0;
}
switch (pnd->reason) {
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);
break;
}
/*
* Set S_DONE before migrating the vmstate, so the guest will reuse
* all hinted pages once running on the destination. Fall through.
*/
case PRECOPY_NOTIFY_CLEANUP:
/*
* Especially, if something goes wrong during precopy or if migration
* is canceled, we have to properly communicate S_DONE to the VM.
*/
virtio_balloon_free_page_done(dev);
break;
case PRECOPY_NOTIFY_SETUP:
case PRECOPY_NOTIFY_COMPLETE:
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_hint_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_hint_status == FREE_PAGE_HINT_S_REQUESTED) {
config.free_page_hint_cmd_id =
cpu_to_le32(dev->free_page_hint_cmd_id);
} else if (dev->free_page_hint_status == FREE_PAGE_HINT_S_STOP) {
config.free_page_hint_cmd_id =
cpu_to_le32(VIRTIO_BALLOON_CMD_ID_STOP);
} else if (dev->free_page_hint_status == FREE_PAGE_HINT_S_DONE) {
config.free_page_hint_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 ram_addr_t get_current_ram_size(void)
{
MachineState *machine = MACHINE(qdev_get_machine());
if (machine->device_memory) {
return machine->ram_size + machine->device_memory->dimm_size;
} else {
return machine->ram_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_hint = {
.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_hint_cmd_id, VirtIOBalloon),
VMSTATE_UINT32(free_page_hint_status, VirtIOBalloon),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription vmstate_virtio_balloon_page_poison = {
.name = "virtio-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_hint,
&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_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_hint_notify);
object_ref(OBJECT(s->iothread));
s->free_page_bh = aio_bh_new_guarded(iothread_get_aio_context(s->iothread),
virtio_ballloon_get_free_page_hints, s,
&dev->mem_reentrancy_guard);
}
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_hint_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_hint_cmd_id = VIRTIO_BALLOON_FREE_PAGE_HINT_CMD_ID_MIN;
s->free_page_hint_notify.notify = virtio_balloon_free_page_hint_notify;
object_property_add(obj, "guest-stats", "guest statistics",
balloon_stats_get_all, NULL, NULL, NULL);
object_property_add(obj, "guest-stats-polling-interval", "int",
balloon_stats_get_poll_interval,
balloon_stats_set_poll_interval,
NULL, NULL);
}
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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