When working with the VM state (for loadvm/savevm and migration), it is not valid to load and store pointers since the validity of those pointers cannot be assured in the new qemu address space. Therefore, virtio_balloon_save() and virtio_balloon_load() must not handle the stats-related fields in struct VirtIOBalloon. If a memory stats request is in-flight at the time of a migration or savevm, the request will not complete and should be resubmitted once migration or loadvm completes. Note that this extremely small race window can only be triggered using QMP so it is not possible to hang the user monitor. Signed-off-by: Adam Litke <agl@us.ibm.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
303 lines
8.5 KiB
C
303 lines
8.5 KiB
C
/*
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* Virtio Block Device
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*
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* Copyright IBM, Corp. 2008
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#include "qemu-common.h"
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#include "virtio.h"
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#include "pc.h"
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#include "sysemu.h"
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#include "cpu.h"
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#include "monitor.h"
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#include "balloon.h"
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#include "virtio-balloon.h"
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#include "kvm.h"
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#include "qlist.h"
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#include "qint.h"
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#include "qstring.h"
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#if defined(__linux__)
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#include <sys/mman.h>
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#endif
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typedef struct VirtIOBalloon
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{
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VirtIODevice vdev;
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VirtQueue *ivq, *dvq, *svq;
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uint32_t num_pages;
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uint32_t actual;
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uint64_t stats[VIRTIO_BALLOON_S_NR];
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VirtQueueElement stats_vq_elem;
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size_t stats_vq_offset;
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MonitorCompletion *stats_callback;
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void *stats_opaque_callback_data;
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} VirtIOBalloon;
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static VirtIOBalloon *to_virtio_balloon(VirtIODevice *vdev)
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{
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return (VirtIOBalloon *)vdev;
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}
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static void balloon_page(void *addr, int deflate)
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{
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#if defined(__linux__)
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if (!kvm_enabled() || kvm_has_sync_mmu())
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madvise(addr, TARGET_PAGE_SIZE,
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deflate ? MADV_WILLNEED : MADV_DONTNEED);
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#endif
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}
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/*
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* reset_stats - Mark all items in the stats array as unset
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*
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* This function needs to be called at device intialization and before
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* before updating to a set of newly-generated stats. This will ensure that no
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* stale values stick around in case the guest reports a subset of the supported
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* statistics.
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*/
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static inline void reset_stats(VirtIOBalloon *dev)
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{
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int i;
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for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
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}
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static void stat_put(QDict *dict, const char *label, uint64_t val)
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{
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if (val != -1)
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qdict_put(dict, label, qint_from_int(val));
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}
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static QObject *get_stats_qobject(VirtIOBalloon *dev)
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{
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QDict *dict = qdict_new();
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uint32_t actual = ram_size - (dev->actual << VIRTIO_BALLOON_PFN_SHIFT);
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stat_put(dict, "actual", actual);
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stat_put(dict, "mem_swapped_in", dev->stats[VIRTIO_BALLOON_S_SWAP_IN]);
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stat_put(dict, "mem_swapped_out", dev->stats[VIRTIO_BALLOON_S_SWAP_OUT]);
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stat_put(dict, "major_page_faults", dev->stats[VIRTIO_BALLOON_S_MAJFLT]);
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stat_put(dict, "minor_page_faults", dev->stats[VIRTIO_BALLOON_S_MINFLT]);
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stat_put(dict, "free_mem", dev->stats[VIRTIO_BALLOON_S_MEMFREE]);
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stat_put(dict, "total_mem", dev->stats[VIRTIO_BALLOON_S_MEMTOT]);
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return QOBJECT(dict);
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}
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/* FIXME: once we do a virtio refactoring, this will get subsumed into common
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* code */
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static size_t memcpy_from_iovector(void *data, size_t offset, size_t size,
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struct iovec *iov, int iovlen)
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{
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int i;
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uint8_t *ptr = data;
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size_t iov_off = 0;
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size_t data_off = 0;
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for (i = 0; i < iovlen && size; i++) {
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if (offset < (iov_off + iov[i].iov_len)) {
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size_t len = MIN((iov_off + iov[i].iov_len) - offset , size);
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memcpy(ptr + data_off, iov[i].iov_base + (offset - iov_off), len);
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data_off += len;
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offset += len;
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size -= len;
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}
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iov_off += iov[i].iov_len;
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}
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return data_off;
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}
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static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
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{
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VirtIOBalloon *s = to_virtio_balloon(vdev);
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VirtQueueElement elem;
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while (virtqueue_pop(vq, &elem)) {
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size_t offset = 0;
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uint32_t pfn;
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while (memcpy_from_iovector(&pfn, offset, 4,
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elem.out_sg, elem.out_num) == 4) {
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ram_addr_t pa;
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ram_addr_t addr;
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pa = (ram_addr_t)ldl_p(&pfn) << VIRTIO_BALLOON_PFN_SHIFT;
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offset += 4;
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addr = cpu_get_physical_page_desc(pa);
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if ((addr & ~TARGET_PAGE_MASK) != IO_MEM_RAM)
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continue;
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/* Using qemu_get_ram_ptr is bending the rules a bit, but
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should be OK because we only want a single page. */
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balloon_page(qemu_get_ram_ptr(addr), !!(vq == s->dvq));
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}
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virtqueue_push(vq, &elem, offset);
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virtio_notify(vdev, vq);
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}
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}
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static void complete_stats_request(VirtIOBalloon *vb)
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{
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QObject *stats;
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if (!vb->stats_opaque_callback_data)
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return;
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stats = get_stats_qobject(vb);
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vb->stats_callback(vb->stats_opaque_callback_data, stats);
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qobject_decref(stats);
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vb->stats_opaque_callback_data = NULL;
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vb->stats_callback = NULL;
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}
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static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
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{
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VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
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VirtQueueElement *elem = &s->stats_vq_elem;
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VirtIOBalloonStat stat;
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size_t offset = 0;
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if (!virtqueue_pop(vq, elem)) {
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return;
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}
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/* Initialize the stats to get rid of any stale values. This is only
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* needed to handle the case where a guest supports fewer stats than it
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* used to (ie. it has booted into an old kernel).
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*/
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reset_stats(s);
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while (memcpy_from_iovector(&stat, offset, sizeof(stat), elem->out_sg,
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elem->out_num) == sizeof(stat)) {
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uint16_t tag = tswap16(stat.tag);
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uint64_t val = tswap64(stat.val);
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offset += sizeof(stat);
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if (tag < VIRTIO_BALLOON_S_NR)
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s->stats[tag] = val;
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}
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s->stats_vq_offset = offset;
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complete_stats_request(s);
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}
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static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
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{
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VirtIOBalloon *dev = to_virtio_balloon(vdev);
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struct virtio_balloon_config config;
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config.num_pages = cpu_to_le32(dev->num_pages);
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config.actual = cpu_to_le32(dev->actual);
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memcpy(config_data, &config, 8);
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}
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static void virtio_balloon_set_config(VirtIODevice *vdev,
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const uint8_t *config_data)
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{
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VirtIOBalloon *dev = to_virtio_balloon(vdev);
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struct virtio_balloon_config config;
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memcpy(&config, config_data, 8);
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dev->actual = config.actual;
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}
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static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
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{
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f |= (1 << VIRTIO_BALLOON_F_STATS_VQ);
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return f;
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}
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static void virtio_balloon_to_target(void *opaque, ram_addr_t target,
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MonitorCompletion cb, void *cb_data)
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{
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VirtIOBalloon *dev = opaque;
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if (target > ram_size)
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target = ram_size;
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if (target) {
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dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
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virtio_notify_config(&dev->vdev);
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} else {
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/* For now, only allow one request at a time. This restriction can be
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* removed later by queueing callback and data pairs.
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*/
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if (dev->stats_callback != NULL) {
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return;
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}
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dev->stats_callback = cb;
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dev->stats_opaque_callback_data = cb_data;
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if (dev->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ)) {
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virtqueue_push(dev->svq, &dev->stats_vq_elem, dev->stats_vq_offset);
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virtio_notify(&dev->vdev, dev->svq);
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} else {
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/* Stats are not supported. Clear out any stale values that might
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* have been set by a more featureful guest kernel.
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*/
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reset_stats(dev);
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complete_stats_request(dev);
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}
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}
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}
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static void virtio_balloon_save(QEMUFile *f, void *opaque)
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{
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VirtIOBalloon *s = opaque;
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virtio_save(&s->vdev, f);
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qemu_put_be32(f, s->num_pages);
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qemu_put_be32(f, s->actual);
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}
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static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
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{
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VirtIOBalloon *s = opaque;
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if (version_id != 1)
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return -EINVAL;
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virtio_load(&s->vdev, f);
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s->num_pages = qemu_get_be32(f);
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s->actual = qemu_get_be32(f);
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return 0;
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}
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VirtIODevice *virtio_balloon_init(DeviceState *dev)
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{
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VirtIOBalloon *s;
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s = (VirtIOBalloon *)virtio_common_init("virtio-balloon",
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VIRTIO_ID_BALLOON,
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8, sizeof(VirtIOBalloon));
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s->vdev.get_config = virtio_balloon_get_config;
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s->vdev.set_config = virtio_balloon_set_config;
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s->vdev.get_features = virtio_balloon_get_features;
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s->ivq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
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s->dvq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
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s->svq = virtio_add_queue(&s->vdev, 128, virtio_balloon_receive_stats);
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reset_stats(s);
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qemu_add_balloon_handler(virtio_balloon_to_target, s);
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register_savevm("virtio-balloon", -1, 1, virtio_balloon_save, virtio_balloon_load, s);
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return &s->vdev;
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}
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