/* * Virtio Balloon Device * * Copyright IBM, Corp. 2008 * Copyright (C) 2011 Red Hat, Inc. * Copyright (C) 2011 Amit Shah * * Authors: * Anthony Liguori * * 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 "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 */ } } /* * All stats upto VIRTIO_BALLOON_S_NR /must/ have a * non-NULL name declared here, since these are used * as keys for populating the QDict with stats */ 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_OOM_KILL] = "stat-oom-kills", [VIRTIO_BALLOON_S_ALLOC_STALL] = "stat-alloc-stalls", [VIRTIO_BALLOON_S_ASYNC_SCAN] = "stat-async-scans", [VIRTIO_BALLOON_S_DIRECT_SCAN] = "stat-direct-scans", [VIRTIO_BALLOON_S_ASYNC_RECLAIM] = "stat-async-reclaims", [VIRTIO_BALLOON_S_DIRECT_RECLAIM] = "stat-direct-reclaims", }; G_STATIC_ASSERT(G_N_ELEMENTS(balloon_stat_names) == VIRTIO_BALLOON_S_NR); /* * 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, Error **errp) { 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 = (const 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 = (const 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 = (const VMStateField[]) { VMSTATE_UINT32(num_pages, VirtIOBalloon), VMSTATE_UINT32(actual, VirtIOBalloon), VMSTATE_END_OF_LIST() }, .subsections = (const VMStateDescription * const []) { &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 = (const 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)