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87b245db05
qemu/hw/virtio-blk.c
Christoph Hellwig 87b245db05 virtio-blk: handle NULL returns from bdrv_aio_{read, write} 
The bdrv_aio_{read,write} routines can return a NULL pointer when the
I/O submission fails.  Currently we ignore this and will wait forever
for an I/O completion and leading to a hang of the guest.

I can easily reproduce this using the native Linux AIO patch, but it's
also possible using normal pthreads-based AIO.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-08-27 20:30:23 -05:00

459 lines
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/*
* 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;
char serial_str[BLOCK_SERIAL_STRLEN + 1];
QEMUBH *bh;
} VirtIOBlock;
static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
{
return (VirtIOBlock *)vdev;
}
/* store identify data in little endian format
*/
static inline void put_le16(uint16_t *p, unsigned int v)
{
*p = cpu_to_le16(v);
}
/* copy to *dst from *src, nul pad dst tail as needed to len bytes
*/
static inline void padstr(char *dst, const char *src, int len)
{
while (len--)
*dst++ = *src ? *src++ : '\0';
}
/* setup simulated identify data as appropriate for virtio block device
*
* ref: AT Attachment 8 - ATA/ATAPI Command Set (ATA8-ACS)
*/
static inline void virtio_identify_template(struct virtio_blk_config *bc)
{
uint16_t *p = &bc->identify[0];
uint64_t lba_sectors = bc->capacity;
memset(p, 0, sizeof(bc->identify));
put_le16(p + 0, 0x0); /* ATA device */
padstr((char *)(p + 23), QEMU_VERSION, 8); /* firmware revision */
padstr((char *)(p + 27), "QEMU VIRT_BLK", 40); /* model# */
put_le16(p + 47, 0x80ff); /* max xfer 255 sectors */
put_le16(p + 49, 0x0b00); /* support IORDY/LBA/DMA */
put_le16(p + 59, 0x1ff); /* cur xfer 255 sectors */
put_le16(p + 80, 0x1f0); /* support ATA8/7/6/5/4 */
put_le16(p + 81, 0x16);
put_le16(p + 82, 0x400);
put_le16(p + 83, 0x400);
put_le16(p + 100, lba_sectors);
put_le16(p + 101, lba_sectors >> 16);
put_le16(p + 102, lba_sectors >> 32);
put_le16(p + 103, lba_sectors >> 48);
}
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_write_error(VirtIOBlockReq *req, int error)
{
BlockInterfaceErrorAction action = drive_get_onerror(req->dev->bs);
VirtIOBlock *s = req->dev;
if (action == BLOCK_ERR_IGNORE)
return 0;
if ((error == ENOSPC && action == BLOCK_ERR_STOP_ENOSPC)
|| action == BLOCK_ERR_STOP_ANY) {
req->next = s->rq;
s->rq = req;
vm_stop(0);
} else {
virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
}
return 1;
}
static void virtio_blk_rw_complete(void *opaque, int ret)
{
VirtIOBlockReq *req = opaque;
if (ret && (req->out->type & VIRTIO_BLK_T_OUT)) {
if (virtio_blk_handle_write_error(req, -ret))
return;
}
virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
}
static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
{
VirtIOBlockReq *req = qemu_mallocz(sizeof(*req));
req->dev = s;
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, size = 0;
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;
size = sizeof(*req->in) + sizeof(*req->scsi);
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;
size += hdr.dxfer_len;
} 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;
size += hdr.mx_sb_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 virtio_blk_handle_write(VirtIOBlockReq *req)
{
BlockDriverAIOCB *acb;
acb = bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
req->qiov.size / 512, virtio_blk_rw_complete, req);
if (!acb) {
virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
}
}
static void virtio_blk_handle_read(VirtIOBlockReq *req)
{
BlockDriverAIOCB *acb;
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_req_complete(req, VIRTIO_BLK_S_IOERR);
}
}
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))) {
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) {
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(req);
} else {
qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
req->elem.in_num - 1);
virtio_blk_handle_read(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_dma_restart_bh(void *opaque)
{
VirtIOBlock *s = opaque;
VirtIOBlockReq *req = s->rq;
qemu_bh_delete(s->bh);
s->bh = NULL;
s->rq = NULL;
while (req) {
virtio_blk_handle_write(req);
req = req->next;
}
}
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;
blkcfg.size_max = 0;
virtio_identify_template(&blkcfg);
memcpy(&blkcfg.identify[VIRTIO_BLK_ID_SN], s->serial_str,
VIRTIO_BLK_ID_SN_BYTES);
memcpy(config, &blkcfg, sizeof(blkcfg));
}
static uint32_t virtio_blk_get_features(VirtIODevice *vdev)
{
VirtIOBlock *s = to_virtio_blk(vdev);
uint32_t features = 0;
features |= (1 << VIRTIO_BLK_F_SEG_MAX);
features |= (1 << VIRTIO_BLK_F_GEOMETRY);
#ifdef __linux__
features |= (1 << VIRTIO_BLK_F_SCSI);
#endif
if (strcmp(s->serial_str, "0"))
features |= 1 << VIRTIO_BLK_F_IDENTIFY;
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, DriveInfo *dinfo)
{
VirtIOBlock *s;
int cylinders, heads, secs;
static int virtio_blk_id;
char *ps;
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 = dinfo->bdrv;
s->rq = NULL;
if (strlen(ps = (char *)drive_get_serial(s->bs)))
strncpy(s->serial_str, ps, sizeof(s->serial_str));
else
snprintf(s->serial_str, sizeof(s->serial_str), "0");
s->bs->private = dev;
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);
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;
}
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