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