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 "virtio-blk.h"

#ifdef __linux__

# include <scsi/sg.h>

#endif

typedef struct VirtIOBlock

{

    VirtIODevice vdev;

    BlockDriverState *bs;

    VirtQueue *vq;

    void *rq;

    QEMUBH *bh;

    BlockConf *conf;

    unsigned short sector_mask;

} VirtIOBlock;

static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)

{

    return (VirtIOBlock *)vdev;

}

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_rw_error(VirtIOBlockReq *req, int error,

    int is_read)

{

    BlockInterfaceErrorAction action =

        drive_get_on_error(req->dev->bs, is_read);

    VirtIOBlock *s = req->dev;

    if (action == BLOCK_ERR_IGNORE) {

        bdrv_mon_event(s->bs, BDRV_ACTION_IGNORE, is_read);

        return 0;

    }

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

            || action == BLOCK_ERR_STOP_ANY) {

        req->next = s->rq;

        s->rq = req;

        bdrv_mon_event(s->bs, BDRV_ACTION_STOP, is_read);

        vm_stop(0);

    } else {

        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);

        bdrv_mon_event(s->bs, BDRV_ACTION_REPORT, is_read);

    }

    return 1;

}

static void virtio_blk_rw_complete(void *opaque, int ret)

{

    VirtIOBlockReq *req = opaque;

    if (ret) {

        int is_read = !(req->out->type & VIRTIO_BLK_T_OUT);

        if (virtio_blk_handle_rw_error(req, -ret, is_read))

            return;

    }

    virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);

}

static void virtio_blk_flush_complete(void *opaque, int ret)

{

    VirtIOBlockReq *req = opaque;

    virtio_blk_req_complete(req, ret ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK);

}

static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)

{

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

    req->dev = s;

    req->qiov.size = 0;

    req->next = NULL;

    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;

    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;

    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;

    } 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;

    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 do_multiwrite(BlockDriverState *bs, BlockRequest *blkreq,

    int num_writes)

{

    int i, ret;

    ret = bdrv_aio_multiwrite(bs, blkreq, num_writes);

    if (ret != 0) {

        for (i = 0; i < num_writes; i++) {

            if (blkreq[i].error) {

                virtio_blk_rw_complete(blkreq[i].opaque, -EIO);

            }

        }

    }

}

static void virtio_blk_handle_flush(BlockRequest *blkreq, int *num_writes,

    VirtIOBlockReq *req, BlockDriverState **old_bs)

{

    BlockDriverAIOCB *acb;

    /*

     * Make sure all outstanding writes are posted to the backing device.

     */

    if (*old_bs != NULL) {

        do_multiwrite(*old_bs, blkreq, *num_writes);

    }

    *num_writes = 0;

    *old_bs = req->dev->bs;

    acb = bdrv_aio_flush(req->dev->bs, virtio_blk_flush_complete, req);

    if (!acb) {

        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);

    }

}

static void virtio_blk_handle_write(BlockRequest *blkreq, int *num_writes,

    VirtIOBlockReq *req, BlockDriverState **old_bs)

{

    if (req->out->sector & req->dev->sector_mask) {

        virtio_blk_rw_complete(req, -EIO);

        return;

    }

    if (req->dev->bs != *old_bs || *num_writes == 32) {

        if (*old_bs != NULL) {

            do_multiwrite(*old_bs, blkreq, *num_writes);

        }

        *num_writes = 0;

        *old_bs = req->dev->bs;

    }

    blkreq[*num_writes].sector = req->out->sector;

    blkreq[*num_writes].nb_sectors = req->qiov.size / BDRV_SECTOR_SIZE;

    blkreq[*num_writes].qiov = &req->qiov;

    blkreq[*num_writes].cb = virtio_blk_rw_complete;

    blkreq[*num_writes].opaque = req;

    blkreq[*num_writes].error = 0;

    (*num_writes)++;

}

static void virtio_blk_handle_read(VirtIOBlockReq *req)

{

    BlockDriverAIOCB *acb;

    if (req->out->sector & req->dev->sector_mask) {

        virtio_blk_rw_complete(req, -EIO);

        return;

    }

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

                         req->qiov.size / BDRV_SECTOR_SIZE,

                         virtio_blk_rw_complete, req);

    if (!acb) {

        virtio_blk_rw_complete(req, -EIO);

    }

}

typedef struct MultiReqBuffer {

    BlockRequest        blkreq[32];

    int                 num_writes;

    BlockDriverState    *old_bs;

} MultiReqBuffer;

static void virtio_blk_handle_request(VirtIOBlockReq *req,

    MultiReqBuffer *mrb)

{

    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_FLUSH) {

        virtio_blk_handle_flush(mrb->blkreq, &mrb->num_writes,

            req, &mrb->old_bs);

    } else 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(mrb->blkreq, &mrb->num_writes,

            req, &mrb->old_bs);

    } else {

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

                                 req->elem.in_num - 1);

        virtio_blk_handle_read(req);

    }

}

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

{

    VirtIOBlock *s = to_virtio_blk(vdev);

    VirtIOBlockReq *req;

    MultiReqBuffer mrb = {

        .num_writes = 0,

        .old_bs = NULL,

    };

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

        virtio_blk_handle_request(req, &mrb);

    }

    if (mrb.num_writes > 0) {

        do_multiwrite(mrb.old_bs, mrb.blkreq, mrb.num_writes);

    }

    /*

     * 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;

    MultiReqBuffer mrb = {

        .num_writes = 0,

        .old_bs = NULL,

    };

    qemu_bh_delete(s->bh);

    s->bh = NULL;

    s->rq = NULL;

    while (req) {

        virtio_blk_handle_request(req, &mrb);

        req = req->next;

    }

    if (mrb.num_writes > 0) {

        do_multiwrite(mrb.old_bs, mrb.blkreq, mrb.num_writes);

    }

}

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 & ~s->sector_mask;

    blkcfg.blk_size = s->conf->logical_block_size;

    blkcfg.size_max = 0;

    blkcfg.physical_block_exp = get_physical_block_exp(s->conf);

    blkcfg.alignment_offset = 0;

    blkcfg.min_io_size = s->conf->min_io_size / blkcfg.blk_size;

    blkcfg.opt_io_size = s->conf->opt_io_size / blkcfg.blk_size;

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

}

static uint32_t virtio_blk_get_features(VirtIODevice *vdev, uint32_t features)

{

    VirtIOBlock *s = to_virtio_blk(vdev);

    features |= (1 << VIRTIO_BLK_F_SEG_MAX);

    features |= (1 << VIRTIO_BLK_F_GEOMETRY);

    features |= (1 << VIRTIO_BLK_F_TOPOLOGY);

    features |= (1 << VIRTIO_BLK_F_BLK_SIZE);

    if (bdrv_enable_write_cache(s->bs))

        features |= (1 << VIRTIO_BLK_F_WCACHE);

    if (bdrv_is_read_only(s->bs))

        features |= 1 << VIRTIO_BLK_F_RO;

    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, BlockConf *conf)

{

    VirtIOBlock *s;

    int cylinders, heads, secs;

    static int virtio_blk_id;

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

                                          sizeof(struct virtio_blk_config),

                                          sizeof(VirtIOBlock));

    s->vdev.get_config = virtio_blk_update_config;

    s->vdev.get_features = virtio_blk_get_features;

    s->vdev.reset = virtio_blk_reset;

    s->bs = conf->dinfo->bdrv;

    s->conf = conf;

    s->rq = NULL;

    s->sector_mask = (s->conf->logical_block_size / BDRV_SECTOR_SIZE) - 1;

    bdrv_guess_geometry(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;

}