hw/virtio-balloon.c

   1 /*
   2  * Virtio Balloon Device
   3  *
   4  * Copyright IBM, Corp. 2008
   5  * Copyright (C) 2011 Red Hat, Inc.
   6  * Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>
   7  *
   8  * Authors:
   9  *  Anthony Liguori   <aliguori@us.ibm.com>
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2.  See
  12  * the COPYING file in the top-level directory.
  13  *
  14  */
  15
  16 #include "iov.h"
  17 #include "qemu-common.h"
  18 #include "virtio.h"
  19 #include "pc.h"
  20 #include "cpu.h"
  21 #include "balloon.h"
  22 #include "virtio-balloon.h"
  23 #include "kvm.h"
  24
  25 #if defined(__linux__)
  26 #include <sys/mman.h>
  27 #endif
  28
  29 typedef struct VirtIOBalloon
  30 {
  31     VirtIODevice vdev;
  32     VirtQueue *ivq, *dvq, *svq;
  33     uint32_t num_pages;
  34     uint32_t actual;
  35     uint64_t stats[VIRTIO_BALLOON_S_NR];
  36     VirtQueueElement stats_vq_elem;
  37     size_t stats_vq_offset;
  38     DeviceState *qdev;
  39 } VirtIOBalloon;
  40
  41 static VirtIOBalloon *to_virtio_balloon(VirtIODevice *vdev)
  42 {
  43     return (VirtIOBalloon *)vdev;
  44 }
  45
  46 static void balloon_page(void *addr, int deflate)
  47 {
  48 #if defined(__linux__)
  49     if (!kvm_enabled() || kvm_has_sync_mmu())
  50         qemu_madvise(addr, TARGET_PAGE_SIZE,
  51                 deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);
  52 #endif
  53 }
  54
  55 /*
  56  * reset_stats - Mark all items in the stats array as unset
  57  *
  58  * This function needs to be called at device intialization and before
  59  * before updating to a set of newly-generated stats.  This will ensure that no
  60  * stale values stick around in case the guest reports a subset of the supported
  61  * statistics.
  62  */
  63 static inline void reset_stats(VirtIOBalloon *dev)
  64 {
  65     int i;
  66     for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
  67 }
  68
  69 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
  70 {
  71     VirtIOBalloon *s = to_virtio_balloon(vdev);
  72     VirtQueueElement elem;
  73
  74     while (virtqueue_pop(vq, &elem)) {
  75         size_t offset = 0;
  76         uint32_t pfn;
  77
  78         while (iov_to_buf(elem.out_sg, elem.out_num, &pfn, offset, 4) == 4) {
  79             ram_addr_t pa;
  80             ram_addr_t addr;
  81
  82             pa = (ram_addr_t)ldl_p(&pfn) << VIRTIO_BALLOON_PFN_SHIFT;
  83             offset += 4;
  84
  85             addr = cpu_get_physical_page_desc(pa);
  86             if ((addr & ~TARGET_PAGE_MASK) != IO_MEM_RAM)
  87                 continue;
  88
  89             /* Using qemu_get_ram_ptr is bending the rules a bit, but
  90                should be OK because we only want a single page.  */
  91             balloon_page(qemu_get_ram_ptr(addr), !!(vq == s->dvq));
  92         }
  93
  94         virtqueue_push(vq, &elem, offset);
  95         virtio_notify(vdev, vq);
  96     }
  97 }
  98
  99 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
 100 {
 101     VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
 102     VirtQueueElement *elem = &s->stats_vq_elem;
 103     VirtIOBalloonStat stat;
 104     size_t offset = 0;
 105
 106     if (!virtqueue_pop(vq, elem)) {
 107         return;
 108     }
 109
 110     /* Initialize the stats to get rid of any stale values.  This is only
 111      * needed to handle the case where a guest supports fewer stats than it
 112      * used to (ie. it has booted into an old kernel).
 113      */
 114     reset_stats(s);
 115
 116     while (iov_to_buf(elem->out_sg, elem->out_num, &stat, offset, sizeof(stat))
 117            == sizeof(stat)) {
 118         uint16_t tag = tswap16(stat.tag);
 119         uint64_t val = tswap64(stat.val);
 120
 121         offset += sizeof(stat);
 122         if (tag < VIRTIO_BALLOON_S_NR)
 123             s->stats[tag] = val;
 124     }
 125     s->stats_vq_offset = offset;
 126 }
 127
 128 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
 129 {
 130     VirtIOBalloon *dev = to_virtio_balloon(vdev);
 131     struct virtio_balloon_config config;
 132
 133     config.num_pages = cpu_to_le32(dev->num_pages);
 134     config.actual = cpu_to_le32(dev->actual);
 135
 136     memcpy(config_data, &config, 8);
 137 }
 138
 139 static void virtio_balloon_set_config(VirtIODevice *vdev,
 140                                       const uint8_t *config_data)
 141 {
 142     VirtIOBalloon *dev = to_virtio_balloon(vdev);
 143     struct virtio_balloon_config config;
 144     memcpy(&config, config_data, 8);
 145     dev->actual = le32_to_cpu(config.actual);
 146 }
 147
 148 static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
 149 {
 150     f |= (1 << VIRTIO_BALLOON_F_STATS_VQ);
 151     return f;
 152 }
 153
 154 static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
 155 {
 156     VirtIOBalloon *dev = opaque;
 157
 158 #if 0
 159     /* Disable guest-provided stats for now. For more details please check:
 160      * https://bugzilla.redhat.com/show_bug.cgi?id=623903
 161      *
 162      * If you do enable it (which is probably not going to happen as we
 163      * need a new command for it), remember that you also need to fill the
 164      * appropriate members of the BalloonInfo structure so that the stats
 165      * are returned to the client.
 166      */
 167     if (dev->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ)) {
 168         virtqueue_push(dev->svq, &dev->stats_vq_elem, dev->stats_vq_offset);
 169         virtio_notify(&dev->vdev, dev->svq);
 170         return;
 171     }
 172 #endif
 173
 174     /* Stats are not supported.  Clear out any stale values that might
 175      * have been set by a more featureful guest kernel.
 176      */
 177     reset_stats(dev);
 178
 179     info->actual = ram_size - ((uint64_t) dev->actual <<
 180                                VIRTIO_BALLOON_PFN_SHIFT);
 181 }
 182
 183 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
 184 {
 185     VirtIOBalloon *dev = opaque;
 186
 187     if (target > ram_size) {
 188         target = ram_size;
 189     }
 190     if (target) {
 191         dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
 192         virtio_notify_config(&dev->vdev);
 193     }
 194 }
 195
 196 static void virtio_balloon_save(QEMUFile *f, void *opaque)
 197 {
 198     VirtIOBalloon *s = opaque;
 199
 200     virtio_save(&s->vdev, f);
 201
 202     qemu_put_be32(f, s->num_pages);
 203     qemu_put_be32(f, s->actual);
 204 }
 205
 206 static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
 207 {
 208     VirtIOBalloon *s = opaque;
 209
 210     if (version_id != 1)
 211         return -EINVAL;
 212
 213     virtio_load(&s->vdev, f);
 214
 215     s->num_pages = qemu_get_be32(f);
 216     s->actual = qemu_get_be32(f);
 217     return 0;
 218 }
 219
 220 VirtIODevice *virtio_balloon_init(DeviceState *dev)
 221 {
 222     VirtIOBalloon *s;
 223     int ret;
 224
 225     s = (VirtIOBalloon *)virtio_common_init("virtio-balloon",
 226                                             VIRTIO_ID_BALLOON,
 227                                             8, sizeof(VirtIOBalloon));
 228
 229     s->vdev.get_config = virtio_balloon_get_config;
 230     s->vdev.set_config = virtio_balloon_set_config;
 231     s->vdev.get_features = virtio_balloon_get_features;
 232
 233     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
 234                                    virtio_balloon_stat, s);
 235     if (ret < 0) {
 236         virtio_cleanup(&s->vdev);
 237         return NULL;
 238     }
 239
 240     s->ivq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
 241     s->dvq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
 242     s->svq = virtio_add_queue(&s->vdev, 128, virtio_balloon_receive_stats);
 243
 244     reset_stats(s);
 245
 246     s->qdev = dev;
 247     register_savevm(dev, "virtio-balloon", -1, 1,
 248                     virtio_balloon_save, virtio_balloon_load, s);
 249
 250     return &s->vdev;
 251 }
 252
 253 void virtio_balloon_exit(VirtIODevice *vdev)
 254 {
 255     VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
 256
 257     qemu_remove_balloon_handler(s);
 258     unregister_savevm(s->qdev, "virtio-balloon", s);
 259     virtio_cleanup(vdev);
 260 }