2008-12-04 20:52:44 +01:00
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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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#ifndef _QEMU_VIRTIO_BLK_H
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#define _QEMU_VIRTIO_BLK_H
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2015-02-16 22:36:03 +01:00
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#include "standard-headers/linux/virtio_blk.h"
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2013-02-05 17:06:20 +01:00
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#include "hw/virtio/virtio.h"
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#include "hw/block/block.h"
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2014-03-03 11:30:08 +01:00
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#include "sysemu/iothread.h"
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2014-10-07 13:59:18 +02:00
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#include "sysemu/block-backend.h"
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2008-12-04 20:52:44 +01:00
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2013-04-09 12:04:48 +02:00
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#define TYPE_VIRTIO_BLK "virtio-blk-device"
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2013-03-18 17:37:22 +01:00
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#define VIRTIO_BLK(obj) \
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OBJECT_CHECK(VirtIOBlock, (obj), TYPE_VIRTIO_BLK)
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2009-04-23 12:58:51 +02:00
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/* This is the last element of the write scatter-gather list */
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2008-12-04 20:52:44 +01:00
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struct virtio_blk_inhdr
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{
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unsigned char status;
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};
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2012-05-16 12:54:05 +02:00
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struct VirtIOBlkConf
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{
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BlockConf conf;
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2014-03-03 11:30:08 +01:00
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IOThread *iothread;
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2012-05-16 12:54:05 +02:00
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char *serial;
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virtio-blk: always enable VIRTIO_BLK_F_SCSI
VIRTIO_BLK_F_SCSI is supposed to mean whether the host can *parse*
SCSI requests, not *execute* them. You could run QEMU with scsi=on
and a file-backed disk, and QEMU would fail all SCSI requests even
though it advertises VIRTIO_BLK_F_SCSI.
Because we need to do this to fix a migration compatibility problem
related to how QEMU is invoked by management, we must do this
unconditionally even on older machine types. This more or less assumes
that no one ever invoked QEMU with scsi=off.
Here is how testing goes:
- old QEMU, scsi=on -> new QEMU, scsi=on
- new QEMU, scsi=on -> old QEMU, scsi=on
- old QEMU, scsi=off -> new QEMU, scsi=on
- new QEMU, scsi=off -> old QEMU, scsi=on
ok (new QEMU has VIRTIO_BLK_F_SCSI, adding host features is fine)
- old QEMU, scsi=off -> new QEMU, scsi=off
ok (new QEMU has VIRTIO_BLK_F_SCSI, adding host features is fine)
- old QEMU, scsi=on -> new QEMU, scsi=off
ok, bug fixed
- new QEMU, scsi=on -> old QEMU, scsi=off
doesn't work (same as: old QEMU, scsi=on -> old QEMU, scsi=off)
- new QEMU, scsi=off -> old QEMU, scsi=off
broken by the patch
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-05-16 12:54:06 +02:00
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uint32_t scsi;
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2012-12-10 13:14:39 +01:00
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uint32_t config_wce;
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2012-11-14 15:39:30 +01:00
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uint32_t data_plane;
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2015-02-02 14:52:22 +01:00
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uint32_t request_merging;
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2012-05-16 12:54:05 +02:00
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};
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2013-02-05 17:06:20 +01:00
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struct VirtIOBlockDataPlane;
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2014-06-17 08:32:06 +02:00
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struct VirtIOBlockReq;
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2013-03-18 17:37:18 +01:00
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typedef struct VirtIOBlock {
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2013-03-18 17:37:27 +01:00
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VirtIODevice parent_obj;
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2014-10-07 13:59:18 +02:00
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BlockBackend *blk;
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2013-03-18 17:37:18 +01:00
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VirtQueue *vq;
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void *rq;
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QEMUBH *bh;
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2014-10-07 13:59:17 +02:00
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VirtIOBlkConf conf;
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2013-03-18 17:37:18 +01:00
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unsigned short sector_mask;
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virtio-blk: do not relay a previous driver's WCE configuration to the current
The following sequence happens:
- the SeaBIOS virtio-blk driver does not support the WCE feature, which
causes QEMU to disable writeback caching
- the Linux virtio-blk driver resets the device, finds WCE is available
but writeback caching is disabled; tells block layer to not send cache
flush commands
- the Linux virtio-blk driver sets the DRIVER_OK bit, which causes
writeback caching to be re-enabled, but the Linux virtio-blk driver does
not know of this side effect and cache flushes remain disabled
The bug is at the third step. If the guest does know about CONFIG_WCE,
QEMU should ignore the WCE feature's state. The guest will control the
cache mode solely using configuration space. This change makes Linux
do flushes correctly, but Linux will keep SeaBIOS's writethrough mode.
Hence, whenever the guest is reset, the cache mode of the disk should
be reset to whatever was specified in the "-drive" option. With this
change, the Linux virtio-blk driver finds that writeback caching is
enabled, and tells the block layer to send cache flush commands
appropriately.
Reported-by: Rusty Russell <rusty@au1.ibm.com
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-09-20 17:31:55 +02:00
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bool original_wce;
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2013-03-18 17:37:18 +01:00
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VMChangeStateEntry *change;
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2014-06-17 08:32:06 +02:00
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/* Function to push to vq and notify guest */
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void (*complete_request)(struct VirtIOBlockReq *req, unsigned char status);
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2013-07-29 15:01:59 +02:00
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Notifier migration_state_notifier;
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2013-02-05 17:06:20 +01:00
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struct VirtIOBlockDataPlane *dataplane;
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2013-03-18 17:37:18 +01:00
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} VirtIOBlock;
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2014-06-11 06:11:42 +02:00
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typedef struct VirtIOBlockReq {
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2015-02-02 14:52:21 +01:00
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int64_t sector_num;
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2014-06-11 06:11:42 +02:00
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VirtIOBlock *dev;
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2014-07-09 10:05:49 +02:00
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VirtQueueElement elem;
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2014-06-11 06:11:42 +02:00
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struct virtio_blk_inhdr *in;
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2014-06-11 06:11:48 +02:00
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struct virtio_blk_outhdr out;
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2014-06-11 06:11:42 +02:00
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QEMUIOVector qiov;
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struct VirtIOBlockReq *next;
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2015-02-02 14:52:21 +01:00
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struct VirtIOBlockReq *mr_next;
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2014-06-11 06:11:42 +02:00
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BlockAcctCookie acct;
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} VirtIOBlockReq;
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2015-02-02 14:52:21 +01:00
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#define VIRTIO_BLK_MAX_MERGE_REQS 32
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typedef struct MultiReqBuffer {
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VirtIOBlockReq *reqs[VIRTIO_BLK_MAX_MERGE_REQS];
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unsigned int num_reqs;
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bool is_write;
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} MultiReqBuffer;
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2014-07-09 10:05:49 +02:00
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VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s);
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void virtio_blk_free_request(VirtIOBlockReq *req);
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2014-06-17 08:32:07 +02:00
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void virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb);
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2015-02-02 14:52:21 +01:00
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void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb);
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2014-06-17 08:32:07 +02:00
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2008-12-04 20:52:44 +01:00
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#endif
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