/*

 * 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 "virtio-blk.h"

#include "block_int.h"

typedef struct VirtIOBlock

{

    VirtIODevice vdev;

    BlockDriverState *bs;

    VirtQueue *vq;

} 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;

    size_t size;

    uint8_t *buffer;

} VirtIOBlockReq;

static void virtio_blk_rw_complete(void *opaque, int ret)

{

    VirtIOBlockReq *req = opaque;

    VirtIOBlock *s = req->dev;

    /* Copy read data to the guest */

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

        size_t offset = 0;

        int i;

        for (i = 0; i < req->elem.in_num - 1; i++) {

            size_t len;

            /* Be pretty defensive wrt malicious guests */

            len = MIN(req->elem.in_sg[i].iov_len,

                      req->size - offset);

            memcpy(req->elem.in_sg[i].iov_base,

                   req->buffer + offset,

                   len);

            offset += len;

        }

    }

    req->in->status = ret ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK;

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

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

    qemu_free(req->buffer);

    qemu_free(req);

}

static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)

{

    VirtIOBlockReq *req;

    req = qemu_mallocz(sizeof(*req));

    if (req == NULL)

        return NULL;

    req->dev = s;

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

        qemu_free(req);

        return NULL;

    }

    return 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))) {

        int i;

        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) {

            unsigned int len = sizeof(*req->in);

            req->in->status = VIRTIO_BLK_S_UNSUPP;

            virtqueue_push(vq, &req->elem, len);

            virtio_notify(vdev, vq);

            qemu_free(req);

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

            size_t offset;

            for (i = 1; i < req->elem.out_num; i++)

                req->size += req->elem.out_sg[i].iov_len;

            req->buffer = qemu_memalign(512, req->size);

            if (req->buffer == NULL) {

                qemu_free(req);

                break;

            }

            /* We copy the data from the SG list to avoid splitting up the request.  This helps

               performance a lot until we can pass full sg lists as AIO operations */

            offset = 0;

            for (i = 1; i < req->elem.out_num; i++) {

                size_t len;

                len = MIN(req->elem.out_sg[i].iov_len,

                          req->size - offset);

                memcpy(req->buffer + offset,

                       req->elem.out_sg[i].iov_base,

                       len);

                offset += len;

            }

            bdrv_aio_write(s->bs, req->out->sector,

                           req->buffer,

                           req->size / 512,

                           virtio_blk_rw_complete,

                           req);

        } else {

            for (i = 0; i < req->elem.in_num - 1; i++)

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

            req->buffer = qemu_memalign(512, req->size);

            if (req->buffer == NULL) {

                qemu_free(req);

                break;

            }

            bdrv_aio_read(s->bs, req->out->sector,

                          req->buffer,

                          req->size / 512,

                          virtio_blk_rw_complete,

                          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_reset(VirtIODevice *vdev)

{

    /*

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

     * are per-device request lists.

     */

    qemu_aio_flush();

}

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);

    stq_raw(&blkcfg.capacity, capacity);

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

    stw_raw(&blkcfg.cylinders, cylinders);

    blkcfg.heads = heads;

    blkcfg.sectors = secs;

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

}

static uint32_t virtio_blk_get_features(VirtIODevice *vdev)

{

    return (1 << VIRTIO_BLK_F_SEG_MAX | 1 << VIRTIO_BLK_F_GEOMETRY);

}

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

{

    VirtIOBlock *s = opaque;

    virtio_save(&s->vdev, f);

}

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

{

    VirtIOBlock *s = opaque;

    if (version_id != 1)

        return -EINVAL;

    virtio_load(&s->vdev, f);

    return 0;

}

void virtio_blk_init(VirtIOBindFn bind, void *bind_arg, BlockDriverState *bs)

{

    VirtIOBlock *s;

    int cylinders, heads, secs;

    static int virtio_blk_id;

    s = (VirtIOBlock *)bind(bind_arg, "virtio-blk", 0, VIRTIO_ID_BLOCK,

                            sizeof(struct virtio_blk_config),

                            sizeof(VirtIOBlock));

    if (!s)

        return;

    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;

    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);

    register_savevm("virtio-blk", virtio_blk_id++, 1,

                    virtio_blk_save, virtio_blk_load, s);

}