hw/virtio-balloon.c

   1 /*
   2  * Virtio Block Device
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu-common.h"
  15 #include "virtio.h"
  16 #include "pc.h"
  17 #include "sysemu.h"
  18 #include "cpu.h"
  19 #include "balloon.h"
  20 #include "virtio-balloon.h"
  21 #include "kvm.h"
  22 #include "qemu-kvm.h"
  23
  24 #if defined(__linux__)
  25 #include <sys/mman.h>
  26 #endif
  27
  28 typedef struct VirtIOBalloon
  29 {
  30     VirtIODevice vdev;
  31     VirtQueue *ivq, *dvq;
  32     uint32_t num_pages;
  33     uint32_t actual;
  34 } VirtIOBalloon;
  35
  36 static VirtIOBalloon *to_virtio_balloon(VirtIODevice *vdev)
  37 {
  38     return (VirtIOBalloon *)vdev;
  39 }
  40
  41 static void balloon_page(void *addr, int deflate)
  42 {
  43 #if defined(__linux__)
  44     if (!kvm_enabled() || kvm_has_sync_mmu())
  45         madvise(addr, TARGET_PAGE_SIZE,
  46                 deflate ? MADV_WILLNEED : MADV_DONTNEED);
  47 #endif
  48 }
  49
  50 /* FIXME: once we do a virtio refactoring, this will get subsumed into common
  51  * code */
  52 static size_t memcpy_from_iovector(void *data, size_t offset, size_t size,
  53                                    struct iovec *iov, int iovlen)
  54 {
  55     int i;
  56     uint8_t *ptr = data;
  57     size_t iov_off = 0;
  58     size_t data_off = 0;
  59
  60     for (i = 0; i < iovlen && size; i++) {
  61         if (offset < (iov_off + iov[i].iov_len)) {
  62             size_t len = MIN((iov_off + iov[i].iov_len) - offset , size);
  63
  64             memcpy(ptr + data_off, iov[i].iov_base + (offset - iov_off), len);
  65
  66             data_off += len;
  67             offset += len;
  68             size -= len;
  69         }
  70
  71         iov_off += iov[i].iov_len;
  72     }
  73
  74     return data_off;
  75 }
  76
  77 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
  78 {
  79     VirtIOBalloon *s = to_virtio_balloon(vdev);
  80     VirtQueueElement elem;
  81
  82     while (virtqueue_pop(vq, &elem)) {
  83         size_t offset = 0;
  84         uint32_t pfn;
  85
  86         while (memcpy_from_iovector(&pfn, offset, 4,
  87                                     elem.out_sg, elem.out_num) == 4) {
  88             ram_addr_t pa;
  89             ram_addr_t addr;
  90
  91             pa = (ram_addr_t)ldl_p(&pfn) << VIRTIO_BALLOON_PFN_SHIFT;
  92             offset += 4;
  93
  94             addr = cpu_get_physical_page_desc(pa);
  95             if ((addr & ~TARGET_PAGE_MASK) != IO_MEM_RAM)
  96                 continue;
  97
  98             /* Using qemu_get_ram_ptr is bending the rules a bit, but
  99                should be OK because we only want a single page.  */
 100             balloon_page(qemu_get_ram_ptr(addr), !!(vq == s->dvq));
 101         }
 102
 103         virtqueue_push(vq, &elem, offset);
 104         virtio_notify(vdev, vq);
 105     }
 106 }
 107
 108 static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
 109 {
 110     VirtIOBalloon *dev = to_virtio_balloon(vdev);
 111     struct virtio_balloon_config config;
 112
 113     config.num_pages = cpu_to_le32(dev->num_pages);
 114     config.actual = cpu_to_le32(dev->actual);
 115
 116     memcpy(config_data, &config, 8);
 117 }
 118
 119 static void virtio_balloon_set_config(VirtIODevice *vdev,
 120                                       const uint8_t *config_data)
 121 {
 122     VirtIOBalloon *dev = to_virtio_balloon(vdev);
 123     struct virtio_balloon_config config;
 124     memcpy(&config, config_data, 8);
 125     dev->actual = config.actual;
 126 }
 127
 128 static uint32_t virtio_balloon_get_features(VirtIODevice *vdev)
 129 {
 130     return 0;
 131 }
 132
 133 static ram_addr_t virtio_balloon_to_target(void *opaque, ram_addr_t target)
 134 {
 135     VirtIOBalloon *dev = opaque;
 136
 137     if (target > ram_size)
 138         target = ram_size;
 139
 140     if (target) {
 141         dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
 142         virtio_notify_config(&dev->vdev);
 143     }
 144
 145     return ram_size - (dev->actual << VIRTIO_BALLOON_PFN_SHIFT);
 146 }
 147
 148 static void virtio_balloon_save(QEMUFile *f, void *opaque)
 149 {
 150     VirtIOBalloon *s = opaque;
 151
 152     virtio_save(&s->vdev, f);
 153
 154     qemu_put_be32(f, s->num_pages);
 155     qemu_put_be32(f, s->actual);
 156 }
 157
 158 static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
 159 {
 160     VirtIOBalloon *s = opaque;
 161
 162     if (version_id != 1)
 163         return -EINVAL;
 164
 165     virtio_load(&s->vdev, f);
 166
 167     s->num_pages = qemu_get_be32(f);
 168     s->actual = qemu_get_be32(f);
 169
 170     return 0;
 171 }
 172
 173 VirtIODevice *virtio_balloon_init(DeviceState *dev)
 174 {
 175     VirtIOBalloon *s;
 176
 177     s = (VirtIOBalloon *)virtio_common_init("virtio-balloon",
 178                                             VIRTIO_ID_BALLOON,
 179                                             8, sizeof(VirtIOBalloon));
 180
 181     s->vdev.get_config = virtio_balloon_get_config;
 182     s->vdev.set_config = virtio_balloon_set_config;
 183     s->vdev.get_features = virtio_balloon_get_features;
 184
 185     s->ivq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
 186     s->dvq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
 187
 188     qemu_add_balloon_handler(virtio_balloon_to_target, s);
 189
 190     register_savevm("virtio-balloon", -1, 1, virtio_balloon_save, virtio_balloon_load, s);
 191
 192     return &s->vdev;
 193 }