root / hw / virtio-blk.c @ 53c25cea
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/*
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* Virtio Block Device
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*
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* Copyright IBM, Corp. 2007
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#include <qemu-common.h> |
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#include <sysemu.h> |
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#include "virtio-blk.h" |
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#include "block_int.h" |
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#ifdef __linux__
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# include <scsi/sg.h> |
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#endif
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typedef struct VirtIOBlock |
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{ |
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VirtIODevice vdev; |
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BlockDriverState *bs; |
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VirtQueue *vq; |
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void *rq;
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} VirtIOBlock; |
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static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
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{ |
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return (VirtIOBlock *)vdev;
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} |
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typedef struct VirtIOBlockReq |
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{ |
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VirtIOBlock *dev; |
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VirtQueueElement elem; |
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struct virtio_blk_inhdr *in;
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struct virtio_blk_outhdr *out;
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struct virtio_scsi_inhdr *scsi;
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QEMUIOVector qiov; |
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struct VirtIOBlockReq *next;
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} VirtIOBlockReq; |
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static void virtio_blk_req_complete(VirtIOBlockReq *req, int status) |
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{ |
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VirtIOBlock *s = req->dev; |
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req->in->status = status; |
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virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in));
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virtio_notify(&s->vdev, s->vq); |
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qemu_free(req); |
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} |
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static int virtio_blk_handle_write_error(VirtIOBlockReq *req, int error) |
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{ |
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BlockInterfaceErrorAction action = drive_get_onerror(req->dev->bs); |
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VirtIOBlock *s = req->dev; |
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if (action == BLOCK_ERR_IGNORE)
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return 0; |
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if ((error == ENOSPC && action == BLOCK_ERR_STOP_ENOSPC)
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|| action == BLOCK_ERR_STOP_ANY) { |
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req->next = s->rq; |
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s->rq = req; |
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vm_stop(0);
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} else {
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virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR); |
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} |
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return 1; |
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} |
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static void virtio_blk_rw_complete(void *opaque, int ret) |
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{ |
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VirtIOBlockReq *req = opaque; |
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if (ret && (req->out->type & VIRTIO_BLK_T_OUT)) {
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if (virtio_blk_handle_write_error(req, -ret))
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return;
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} |
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virtio_blk_req_complete(req, VIRTIO_BLK_S_OK); |
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} |
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static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
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{ |
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VirtIOBlockReq *req = qemu_mallocz(sizeof(*req));
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req->dev = s; |
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return req;
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} |
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static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
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{ |
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VirtIOBlockReq *req = virtio_blk_alloc_request(s); |
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if (req != NULL) { |
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if (!virtqueue_pop(s->vq, &req->elem)) {
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qemu_free(req); |
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return NULL; |
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} |
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} |
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return req;
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} |
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#ifdef __linux__
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static void virtio_blk_handle_scsi(VirtIOBlockReq *req) |
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{ |
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struct sg_io_hdr hdr;
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int ret, size = 0; |
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int status;
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int i;
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/*
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* We require at least one output segment each for the virtio_blk_outhdr
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* and the SCSI command block.
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*
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* We also at least require the virtio_blk_inhdr, the virtio_scsi_inhdr
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* and the sense buffer pointer in the input segments.
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*/
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if (req->elem.out_num < 2 || req->elem.in_num < 3) { |
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virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR); |
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return;
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} |
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/*
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* No support for bidirection commands yet.
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*/
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if (req->elem.out_num > 2 && req->elem.in_num > 3) { |
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virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); |
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return;
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} |
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/*
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* The scsi inhdr is placed in the second-to-last input segment, just
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* before the regular inhdr.
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*/
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req->scsi = (void *)req->elem.in_sg[req->elem.in_num - 2].iov_base; |
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size = sizeof(*req->in) + sizeof(*req->scsi); |
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memset(&hdr, 0, sizeof(struct sg_io_hdr)); |
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hdr.interface_id = 'S';
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hdr.cmd_len = req->elem.out_sg[1].iov_len;
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hdr.cmdp = req->elem.out_sg[1].iov_base;
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hdr.dxfer_len = 0;
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if (req->elem.out_num > 2) { |
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/*
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* If there are more than the minimally required 2 output segments
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* there is write payload starting from the third iovec.
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*/
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hdr.dxfer_direction = SG_DXFER_TO_DEV; |
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hdr.iovec_count = req->elem.out_num - 2;
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for (i = 0; i < hdr.iovec_count; i++) |
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hdr.dxfer_len += req->elem.out_sg[i + 2].iov_len;
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hdr.dxferp = req->elem.out_sg + 2;
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} else if (req->elem.in_num > 3) { |
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/*
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* If we have more than 3 input segments the guest wants to actually
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* read data.
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*/
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hdr.dxfer_direction = SG_DXFER_FROM_DEV; |
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hdr.iovec_count = req->elem.in_num - 3;
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for (i = 0; i < hdr.iovec_count; i++) |
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hdr.dxfer_len += req->elem.in_sg[i].iov_len; |
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hdr.dxferp = req->elem.in_sg; |
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size += hdr.dxfer_len; |
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} else {
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/*
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* Some SCSI commands don't actually transfer any data.
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*/
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hdr.dxfer_direction = SG_DXFER_NONE; |
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} |
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hdr.sbp = req->elem.in_sg[req->elem.in_num - 3].iov_base;
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hdr.mx_sb_len = req->elem.in_sg[req->elem.in_num - 3].iov_len;
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size += hdr.mx_sb_len; |
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ret = bdrv_ioctl(req->dev->bs, SG_IO, &hdr); |
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if (ret) {
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status = VIRTIO_BLK_S_UNSUPP; |
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hdr.status = ret; |
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hdr.resid = hdr.dxfer_len; |
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} else if (hdr.status) { |
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status = VIRTIO_BLK_S_IOERR; |
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} else {
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status = VIRTIO_BLK_S_OK; |
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} |
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req->scsi->errors = hdr.status; |
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req->scsi->residual = hdr.resid; |
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req->scsi->sense_len = hdr.sb_len_wr; |
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req->scsi->data_len = hdr.dxfer_len; |
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virtio_blk_req_complete(req, status); |
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} |
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#else
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static void virtio_blk_handle_scsi(VirtIOBlockReq *req) |
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{ |
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virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP); |
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} |
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#endif /* __linux__ */ |
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static void virtio_blk_handle_write(VirtIOBlockReq *req) |
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{ |
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bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov, |
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req->qiov.size / 512, virtio_blk_rw_complete, req);
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} |
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static void virtio_blk_handle_read(VirtIOBlockReq *req) |
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{ |
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bdrv_aio_readv(req->dev->bs, req->out->sector, &req->qiov, |
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req->qiov.size / 512, virtio_blk_rw_complete, req);
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} |
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static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) |
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{ |
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VirtIOBlock *s = to_virtio_blk(vdev); |
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VirtIOBlockReq *req; |
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while ((req = virtio_blk_get_request(s))) {
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if (req->elem.out_num < 1 || req->elem.in_num < 1) { |
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fprintf(stderr, "virtio-blk missing headers\n");
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exit(1);
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} |
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if (req->elem.out_sg[0].iov_len < sizeof(*req->out) || |
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req->elem.in_sg[req->elem.in_num - 1].iov_len < sizeof(*req->in)) { |
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fprintf(stderr, "virtio-blk header not in correct element\n");
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exit(1);
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} |
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req->out = (void *)req->elem.out_sg[0].iov_base; |
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req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base; |
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if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
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virtio_blk_handle_scsi(req); |
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} else if (req->out->type & VIRTIO_BLK_T_OUT) { |
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qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
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req->elem.out_num - 1);
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virtio_blk_handle_write(req); |
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} else {
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qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
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req->elem.in_num - 1);
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virtio_blk_handle_read(req); |
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} |
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} |
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/*
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* FIXME: Want to check for completions before returning to guest mode,
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* so cached reads and writes are reported as quickly as possible. But
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* that should be done in the generic block layer.
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*/
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} |
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static void virtio_blk_dma_restart_cb(void *opaque, int running, int reason) |
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{ |
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VirtIOBlock *s = opaque; |
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VirtIOBlockReq *req = s->rq; |
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if (!running)
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return;
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s->rq = NULL;
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while (req) {
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virtio_blk_handle_write(req); |
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req = req->next; |
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} |
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} |
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static void virtio_blk_reset(VirtIODevice *vdev) |
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{ |
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/*
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* This should cancel pending requests, but can't do nicely until there
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* are per-device request lists.
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*/
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qemu_aio_flush(); |
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} |
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static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config) |
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{ |
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VirtIOBlock *s = to_virtio_blk(vdev); |
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struct virtio_blk_config blkcfg;
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uint64_t capacity; |
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int cylinders, heads, secs;
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bdrv_get_geometry(s->bs, &capacity); |
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bdrv_get_geometry_hint(s->bs, &cylinders, &heads, &secs); |
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stq_raw(&blkcfg.capacity, capacity); |
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stl_raw(&blkcfg.seg_max, 128 - 2); |
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stw_raw(&blkcfg.cylinders, cylinders); |
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blkcfg.heads = heads; |
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blkcfg.sectors = secs; |
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memcpy(config, &blkcfg, sizeof(blkcfg));
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} |
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static uint32_t virtio_blk_get_features(VirtIODevice *vdev)
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{ |
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uint32_t features = 0;
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features |= (1 << VIRTIO_BLK_F_SEG_MAX);
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features |= (1 << VIRTIO_BLK_F_GEOMETRY);
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#ifdef __linux__
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features |= (1 << VIRTIO_BLK_F_SCSI);
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#endif
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return features;
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} |
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static void virtio_blk_save(QEMUFile *f, void *opaque) |
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{ |
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VirtIOBlock *s = opaque; |
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VirtIOBlockReq *req = s->rq; |
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virtio_save(&s->vdev, f); |
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while (req) {
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qemu_put_sbyte(f, 1);
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qemu_put_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem)); |
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req = req->next; |
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} |
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qemu_put_sbyte(f, 0);
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} |
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static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id) |
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{ |
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VirtIOBlock *s = opaque; |
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if (version_id != 2) |
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return -EINVAL;
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virtio_load(&s->vdev, f); |
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while (qemu_get_sbyte(f)) {
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VirtIOBlockReq *req = virtio_blk_alloc_request(s); |
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qemu_get_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem)); |
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req->next = s->rq; |
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s->rq = req->next; |
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} |
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return 0; |
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} |
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VirtIODevice *virtio_blk_init(DeviceState *dev) |
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{ |
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VirtIOBlock *s; |
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int cylinders, heads, secs;
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static int virtio_blk_id; |
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BlockDriverState *bs; |
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s = (VirtIOBlock *)virtio_common_init("virtio-blk", VIRTIO_ID_BLOCK,
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sizeof(struct virtio_blk_config), |
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sizeof(VirtIOBlock));
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bs = qdev_init_bdrv(dev, IF_VIRTIO); |
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s->vdev.get_config = virtio_blk_update_config; |
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s->vdev.get_features = virtio_blk_get_features; |
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s->vdev.reset = virtio_blk_reset; |
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s->bs = bs; |
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s->rq = NULL;
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bs->private = dev; |
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bdrv_guess_geometry(s->bs, &cylinders, &heads, &secs); |
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bdrv_set_geometry_hint(s->bs, cylinders, heads, secs); |
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s->vq = virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);
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qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s); |
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register_savevm("virtio-blk", virtio_blk_id++, 2, |
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virtio_blk_save, virtio_blk_load, s); |
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return &s->vdev;
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} |