qemu/hw/virtio-blk.c

   1 /*
   2  * Virtio Block Device
   3  *
   4  * Copyright IBM, Corp. 2007
   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 "virtio.h"
  15 #include "block.h"
  16 #include "block_int.h"
  17 #include "pc.h"
  18
  19 /* from Linux's linux/virtio_blk.h */
  20
  21 /* The ID for virtio_block */
  22 #define VIRTIO_ID_BLOCK 2
  23
  24 /* Feature bits */
  25 #define VIRTIO_BLK_F_BARRIER    0       /* Does host support barriers? */
  26 #define VIRTIO_BLK_F_SIZE_MAX   1       /* Indicates maximum segment size */
  27 #define VIRTIO_BLK_F_SEG_MAX    2       /* Indicates maximum # of segments */
  28
  29 struct virtio_blk_config
  30 {
  31     uint64_t capacity;
  32     uint32_t size_max;
  33     uint32_t seg_max;
  34 };
  35
  36 /* These two define direction. */
  37 #define VIRTIO_BLK_T_IN         0
  38 #define VIRTIO_BLK_T_OUT        1
  39
  40 /* This bit says it's a scsi command, not an actual read or write. */
  41 #define VIRTIO_BLK_T_SCSI_CMD   2
  42
  43 /* Barrier before this op. */
  44 #define VIRTIO_BLK_T_BARRIER    0x80000000
  45
  46 /* This is the first element of the read scatter-gather list. */
  47 struct virtio_blk_outhdr
  48 {
  49     /* VIRTIO_BLK_T* */
  50     uint32_t type;
  51     /* io priority. */
  52     uint32_t ioprio;
  53     /* Sector (ie. 512 byte offset) */
  54     uint64_t sector;
  55     /* Where to put reply. */
  56     uint64_t id;
  57 };
  58
  59 #define VIRTIO_BLK_S_OK         0
  60 #define VIRTIO_BLK_S_IOERR      1
  61 #define VIRTIO_BLK_S_UNSUPP     2
  62
  63 /* This is the first element of the write scatter-gather list */
  64 struct virtio_blk_inhdr
  65 {
  66     unsigned char status;
  67 };
  68
  69 typedef struct VirtIOBlock
  70 {
  71     VirtIODevice vdev;
  72     BlockDriverState *bs;
  73 } VirtIOBlock;
  74
  75 static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
  76 {
  77     return (VirtIOBlock *)vdev;
  78 }
  79
  80 static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
  81 {
  82     VirtIOBlock *s = to_virtio_blk(vdev);
  83     VirtQueueElement elem;
  84     unsigned int count;
  85
  86     while ((count = virtqueue_pop(vq, &elem)) != 0) {
  87         struct virtio_blk_inhdr *in;
  88         struct virtio_blk_outhdr *out;
  89         unsigned int wlen;
  90         off_t off;
  91         int i;
  92
  93         out = (void *)elem.out_sg[0].iov_base;
  94         in = (void *)elem.in_sg[elem.in_num - 1].iov_base;
  95         off = out->sector;
  96
  97         if (out->type & VIRTIO_BLK_T_SCSI_CMD) {
  98             wlen = sizeof(*in);
  99             in->status = VIRTIO_BLK_S_UNSUPP;
 100         } else if (out->type & VIRTIO_BLK_T_OUT) {
 101             wlen = sizeof(*in);
 102
 103             for (i = 1; i < elem.out_num; i++) {
 104                 bdrv_write(s->bs, off,
 105                            elem.out_sg[i].iov_base,
 106                            elem.out_sg[i].iov_len / 512);
 107                 off += elem.out_sg[i].iov_len / 512;
 108             }
 109
 110             in->status = VIRTIO_BLK_S_OK;
 111         } else {
 112             wlen = sizeof(*in);
 113
 114             for (i = 0; i < elem.in_num - 1; i++) {
 115                 bdrv_read(s->bs, off,
 116                           elem.in_sg[i].iov_base,
 117                           elem.in_sg[i].iov_len / 512);
 118                 off += elem.in_sg[i].iov_len / 512;
 119                 wlen += elem.in_sg[i].iov_len;
 120             }
 121
 122             in->status = VIRTIO_BLK_S_OK;
 123         }
 124
 125         virtqueue_push(vq, &elem, wlen);
 126         virtio_notify(vdev, vq);
 127     }
 128 }
 129
 130 static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
 131 {
 132     VirtIOBlock *s = to_virtio_blk(vdev);
 133     struct virtio_blk_config blkcfg;
 134     int64_t capacity;
 135
 136     bdrv_get_geometry(s->bs, &capacity);
 137     blkcfg.capacity = cpu_to_le64(capacity);
 138     blkcfg.seg_max = cpu_to_le32(128 - 2);
 139     memcpy(config, &blkcfg, sizeof(blkcfg));
 140 }
 141
 142 static uint32_t virtio_blk_get_features(VirtIODevice *vdev)
 143 {
 144     return (1 << VIRTIO_BLK_F_SEG_MAX);
 145 }
 146
 147 void *virtio_blk_init(PCIBus *bus, uint16_t vendor, uint16_t device,
 148                       BlockDriverState *bs)
 149 {
 150     VirtIOBlock *s;
 151
 152     s = (VirtIOBlock *)virtio_init_pci(bus, "virtio-blk", vendor, device,
 153                                        0, VIRTIO_ID_BLOCK,
 154                                        0x01, 0x80, 0x00,
 155                                        16, sizeof(VirtIOBlock));
 156
 157     s->vdev.update_config = virtio_blk_update_config;
 158     s->vdev.get_features = virtio_blk_get_features;
 159     s->bs = bs;
 160     bs->devfn = s->vdev.pci_dev.devfn;
 161
 162     virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);
 163
 164     return s;
 165 }