qemu/hw/virtio-blk.c
Christoph Hellwig 618fbb8429 virtio-blk: fix barrier support
Before issuing the barrier to the block driver we need to flush our oustanding
queue of write requests, as the flush is supposed to be issued after them.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-21 11:49:19 +02:00

519 lines
14 KiB
C

/*
* 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;
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 / 512;
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 / 512, 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 / 512) - 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;
}