Archipelago » qemu

/*

 * Virtio Block Device

 *

 * Copyright IBM, Corp. 2007

 *

 * Authors:

 *  Anthony Liguori   <aliguori@us.ibm.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2.  See

 * the COPYING file in the top-level directory.

 *

 */

#include <qemu-common.h>

#include <sysemu.h>

#include "virtio-blk.h"

#include "block_int.h"

#ifdef __linux__

# include <scsi/sg.h>

#endif

typedef struct VirtIOBlock

{

    VirtIODevice vdev;

    BlockDriverState *bs;

    VirtQueue *vq;

    void *rq;

    char serial_str[BLOCK_SERIAL_STRLEN + 1];

    QEMUBH *bh;

} VirtIOBlock;

static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)

{

    return (VirtIOBlock *)vdev;

}

/* store identify data in little endian format

 */

static inline void put_le16(uint16_t *p, unsigned int v)

{

    *p = cpu_to_le16(v);

}

/* copy to *dst from *src, nul pad dst tail as needed to len bytes

 */

static inline void padstr(char *dst, const char *src, int len)

{

    while (len--)

        *dst++ = *src ? *src++ : '\0';

}

/* setup simulated identify data as appropriate for virtio block device

 *

 * ref: AT Attachment 8 - ATA/ATAPI Command Set (ATA8-ACS)

 */

static inline void virtio_identify_template(struct virtio_blk_config *bc)

{

    uint16_t *p = &bc->identify[0];

    uint64_t lba_sectors = bc->capacity;

    memset(p, 0, sizeof(bc->identify));

    put_le16(p + 0, 0x0);                            /* ATA device */

    padstr((char *)(p + 23), QEMU_VERSION, 8);       /* firmware revision */

    padstr((char *)(p + 27), "QEMU VIRT_BLK", 40);   /* model# */

    put_le16(p + 47, 0x80ff);                        /* max xfer 255 sectors */

    put_le16(p + 49, 0x0b00);                        /* support IORDY/LBA/DMA */

    put_le16(p + 59, 0x1ff);                         /* cur xfer 255 sectors */

    put_le16(p + 80, 0x1f0);                         /* support ATA8/7/6/5/4 */

    put_le16(p + 81, 0x16);

    put_le16(p + 82, 0x400);

    put_le16(p + 83, 0x400);

    put_le16(p + 100, lba_sectors);

    put_le16(p + 101, lba_sectors >> 16);

    put_le16(p + 102, lba_sectors >> 32);

    put_le16(p + 103, lba_sectors >> 48);

}

typedef struct VirtIOBlockReq

{

    VirtIOBlock *dev;

    VirtQueueElement elem;

    struct virtio_blk_inhdr *in;

    struct virtio_blk_outhdr *out;

    struct virtio_scsi_inhdr *scsi;

    QEMUIOVector qiov;

    struct VirtIOBlockReq *next;

} VirtIOBlockReq;

static void virtio_blk_req_complete(VirtIOBlockReq *req, int status)

{

    VirtIOBlock *s = req->dev;

    req->in->status = status;

    virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in));

    virtio_notify(&s->vdev, s->vq);

    qemu_free(req);

}

static int virtio_blk_handle_write_error(VirtIOBlockReq *req, int error)

{

    BlockInterfaceErrorAction action = drive_get_onerror(req->dev->bs);

    VirtIOBlock *s = req->dev;

    if (action == BLOCK_ERR_IGNORE)

        return 0;

    if ((error == ENOSPC && action == BLOCK_ERR_STOP_ENOSPC)

            || action == BLOCK_ERR_STOP_ANY) {

        req->next = s->rq;

        s->rq = req;

        vm_stop(0);

    } else {

        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);

    }

    return 1;

}

static void virtio_blk_rw_complete(void *opaque, int ret)

{

    VirtIOBlockReq *req = opaque;

    if (ret && (req->out->type & VIRTIO_BLK_T_OUT)) {

        if (virtio_blk_handle_write_error(req, -ret))

            return;

    }

    virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);

}

static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)

{

    VirtIOBlockReq *req = qemu_mallocz(sizeof(*req));

    req->dev = s;

    return req;

}

static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)

{

    VirtIOBlockReq *req = virtio_blk_alloc_request(s);

    if (req != NULL) {

        if (!virtqueue_pop(s->vq, &req->elem)) {

            qemu_free(req);

            return NULL;

        }

    }

    return req;

}

#ifdef __linux__

static void virtio_blk_handle_scsi(VirtIOBlockReq *req)

{

    struct sg_io_hdr hdr;

    int ret, size = 0;

    int status;

    int i;

    /*

     * We require at least one output segment each for the virtio_blk_outhdr

     * and the SCSI command block.

     *

     * We also at least require the virtio_blk_inhdr, the virtio_scsi_inhdr

     * and the sense buffer pointer in the input segments.

     */

    if (req->elem.out_num < 2 || req->elem.in_num < 3) {

        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);

        return;

    }

    /*

     * No support for bidirection commands yet.

     */

    if (req->elem.out_num > 2 && req->elem.in_num > 3) {

        virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);

        return;

    }

    /*

     * The scsi inhdr is placed in the second-to-last input segment, just

     * before the regular inhdr.

     */

    req->scsi = (void *)req->elem.in_sg[req->elem.in_num - 2].iov_base;

    size = sizeof(*req->in) + sizeof(*req->scsi);

    memset(&hdr, 0, sizeof(struct sg_io_hdr));

    hdr.interface_id = 'S';

    hdr.cmd_len = req->elem.out_sg[1].iov_len;

    hdr.cmdp = req->elem.out_sg[1].iov_base;

    hdr.dxfer_len = 0;

    if (req->elem.out_num > 2) {

        /*

         * If there are more than the minimally required 2 output segments

         * there is write payload starting from the third iovec.

         */

        hdr.dxfer_direction = SG_DXFER_TO_DEV;

        hdr.iovec_count = req->elem.out_num - 2;

        for (i = 0; i < hdr.iovec_count; i++)

            hdr.dxfer_len += req->elem.out_sg[i + 2].iov_len;

        hdr.dxferp = req->elem.out_sg + 2;

    } else if (req->elem.in_num > 3) {

        /*

         * If we have more than 3 input segments the guest wants to actually

         * read data.

         */

        hdr.dxfer_direction = SG_DXFER_FROM_DEV;

        hdr.iovec_count = req->elem.in_num - 3;

        for (i = 0; i < hdr.iovec_count; i++)

            hdr.dxfer_len += req->elem.in_sg[i].iov_len;

        hdr.dxferp = req->elem.in_sg;

        size += hdr.dxfer_len;

    } else {

        /*

         * Some SCSI commands don't actually transfer any data.

         */

        hdr.dxfer_direction = SG_DXFER_NONE;

    }

    hdr.sbp = req->elem.in_sg[req->elem.in_num - 3].iov_base;

    hdr.mx_sb_len = req->elem.in_sg[req->elem.in_num - 3].iov_len;

    size += hdr.mx_sb_len;

    ret = bdrv_ioctl(req->dev->bs, SG_IO, &hdr);

    if (ret) {

        status = VIRTIO_BLK_S_UNSUPP;

        hdr.status = ret;

        hdr.resid = hdr.dxfer_len;

    } else if (hdr.status) {

        status = VIRTIO_BLK_S_IOERR;

    } else {

        status = VIRTIO_BLK_S_OK;

    }

    req->scsi->errors = hdr.status;

    req->scsi->residual = hdr.resid;

    req->scsi->sense_len = hdr.sb_len_wr;

    req->scsi->data_len = hdr.dxfer_len;

    virtio_blk_req_complete(req, status);

}

#else

static void virtio_blk_handle_scsi(VirtIOBlockReq *req)

{

    virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);

}

#endif /* __linux__ */

static void virtio_blk_handle_write(VirtIOBlockReq *req)

{

    bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,

                    req->qiov.size / 512, virtio_blk_rw_complete, req);

}

static void virtio_blk_handle_read(VirtIOBlockReq *req)

{

    bdrv_aio_readv(req->dev->bs, req->out->sector, &req->qiov,

                   req->qiov.size / 512, virtio_blk_rw_complete, req);

}

static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)

{

    VirtIOBlock *s = to_virtio_blk(vdev);

    VirtIOBlockReq *req;

    while ((req = virtio_blk_get_request(s))) {

        if (req->elem.out_num < 1 || req->elem.in_num < 1) {

            fprintf(stderr, "virtio-blk missing headers\n");

            exit(1);

        }

        if (req->elem.out_sg[0].iov_len < sizeof(*req->out) ||

            req->elem.in_sg[req->elem.in_num - 1].iov_len < sizeof(*req->in)) {

            fprintf(stderr, "virtio-blk header not in correct element\n");

            exit(1);

        }

        req->out = (void *)req->elem.out_sg[0].iov_base;

        req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;

        if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {

            virtio_blk_handle_scsi(req);

        } else if (req->out->type & VIRTIO_BLK_T_OUT) {

            qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],

                                     req->elem.out_num - 1);

            virtio_blk_handle_write(req);

        } else {

            qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],

                                     req->elem.in_num - 1);

            virtio_blk_handle_read(req);

        }

    }

    /*

     * FIXME: Want to check for completions before returning to guest mode,

     * so cached reads and writes are reported as quickly as possible. But

     * that should be done in the generic block layer.

     */

}

static void virtio_blk_dma_restart_bh(void *opaque)

{

    VirtIOBlock *s = opaque;

    VirtIOBlockReq *req = s->rq;

    qemu_bh_delete(s->bh);

    s->bh = NULL;

    s->rq = NULL;

    while (req) {

        virtio_blk_handle_write(req);

        req = req->next;

    }

}

static void virtio_blk_dma_restart_cb(void *opaque, int running, int reason)

{

    VirtIOBlock *s = opaque;

    if (!running)

        return;

    if (!s->bh) {

        s->bh = qemu_bh_new(virtio_blk_dma_restart_bh, s);

        qemu_bh_schedule(s->bh);

    }

}

static void virtio_blk_reset(VirtIODevice *vdev)

{

    /*

     * This should cancel pending requests, but can't do nicely until there

     * are per-device request lists.

     */

    qemu_aio_flush();

}

/* coalesce internal state, copy to pci i/o region 0

 */

static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)

{

    VirtIOBlock *s = to_virtio_blk(vdev);

    struct virtio_blk_config blkcfg;

    uint64_t capacity;

    int cylinders, heads, secs;

    bdrv_get_geometry(s->bs, &capacity);

    bdrv_get_geometry_hint(s->bs, &cylinders, &heads, &secs);

    memset(&blkcfg, 0, sizeof(blkcfg));

    stq_raw(&blkcfg.capacity, capacity);

    stl_raw(&blkcfg.seg_max, 128 - 2);

    stw_raw(&blkcfg.cylinders, cylinders);

    blkcfg.heads = heads;

    blkcfg.sectors = secs;

    blkcfg.size_max = 0;

    virtio_identify_template(&blkcfg);

    memcpy(&blkcfg.identify[VIRTIO_BLK_ID_SN], s->serial_str,

        VIRTIO_BLK_ID_SN_BYTES);

    memcpy(config, &blkcfg, sizeof(blkcfg));

}

static uint32_t virtio_blk_get_features(VirtIODevice *vdev)

{

    VirtIOBlock *s = to_virtio_blk(vdev);

    uint32_t features = 0;

    features |= (1 << VIRTIO_BLK_F_SEG_MAX);

    features |= (1 << VIRTIO_BLK_F_GEOMETRY);

#ifdef __linux__

    features |= (1 << VIRTIO_BLK_F_SCSI);

#endif

    if (strcmp(s->serial_str, "0"))

        features |= 1 << VIRTIO_BLK_F_IDENTIFY;

    return features;

}

static void virtio_blk_save(QEMUFile *f, void *opaque)

{

    VirtIOBlock *s = opaque;

    VirtIOBlockReq *req = s->rq;

    virtio_save(&s->vdev, f);

    while (req) {

        qemu_put_sbyte(f, 1);

        qemu_put_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));

        req = req->next;

    }

    qemu_put_sbyte(f, 0);

}

static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)

{

    VirtIOBlock *s = opaque;

    if (version_id != 2)

        return -EINVAL;

    virtio_load(&s->vdev, f);

    while (qemu_get_sbyte(f)) {

        VirtIOBlockReq *req = virtio_blk_alloc_request(s);

        qemu_get_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));

        req->next = s->rq;

        s->rq = req->next;

    }

    return 0;

}

VirtIODevice *virtio_blk_init(DeviceState *dev)

{

    VirtIOBlock *s;

    int cylinders, heads, secs;

    static int virtio_blk_id;

    BlockDriverState *bs;

    char *ps;

    s = (VirtIOBlock *)virtio_common_init("virtio-blk", VIRTIO_ID_BLOCK,

                                          sizeof(struct virtio_blk_config),

                                          sizeof(VirtIOBlock));

    bs = qdev_init_bdrv(dev, IF_VIRTIO);

    s->vdev.get_config = virtio_blk_update_config;

    s->vdev.get_features = virtio_blk_get_features;

    s->vdev.reset = virtio_blk_reset;

    s->bs = bs;

    s->rq = NULL;

    if (strlen(ps = (char *)drive_get_serial(bs)))

        strncpy(s->serial_str, ps, sizeof(s->serial_str));

    else

        snprintf(s->serial_str, sizeof(s->serial_str), "0");

    bs->private = dev;

    bdrv_guess_geometry(s->bs, &cylinders, &heads, &secs);

    bdrv_set_geometry_hint(s->bs, cylinders, heads, secs);

    s->vq = virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);

    qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);

    register_savevm("virtio-blk", virtio_blk_id++, 2,

                    virtio_blk_save, virtio_blk_load, s);

    return &s->vdev;

}