qemu/hw/virtio-blk.c
aliguori d28a1b6ec6 virtio-blk: use generic vectored I/O APIs (Christoph Hellwig)
Use the generic bdrv_aio_readv/bdrv_aio_writev APIs instead of linearizing
buffers directly.  This enables using the future native preadv/pwritev
support.


Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6903 c046a42c-6fe2-441c-8c8c-71466251a162
2009-03-28 17:46:14 +00:00

275 lines
7.3 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"
typedef struct VirtIOBlock
{
VirtIODevice vdev;
BlockDriverState *bs;
VirtQueue *vq;
void *rq;
} 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;
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;
}
static void virtio_blk_handle_write(VirtIOBlockReq *req)
{
bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
req->qiov.size / 512, virtio_blk_rw_complete, req);
}
static void virtio_blk_handle_read(VirtIOBlockReq *req)
{
bdrv_aio_readv(req->dev->bs, req->out->sector, &req->qiov,
req->qiov.size / 512, virtio_blk_rw_complete, 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))) {
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) {
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_cb(void *opaque, int running, int reason)
{
VirtIOBlock *s = opaque;
VirtIOBlockReq *req = s->rq;
if (!running)
return;
s->rq = NULL;
while (req) {
virtio_blk_handle_write(req);
req = req->next;
}
}
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;
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;
}
void *virtio_blk_init(PCIBus *bus, BlockDriverState *bs)
{
VirtIOBlock *s;
int cylinders, heads, secs;
static int virtio_blk_id;
s = (VirtIOBlock *)virtio_init_pci(bus, "virtio-blk",
PCI_VENDOR_ID_REDHAT_QUMRANET,
PCI_DEVICE_ID_VIRTIO_BLOCK,
PCI_VENDOR_ID_REDHAT_QUMRANET,
VIRTIO_ID_BLOCK,
PCI_CLASS_STORAGE_OTHER, 0x00,
sizeof(struct virtio_blk_config), sizeof(VirtIOBlock));
if (!s)
return NULL;
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;
s->rq = NULL;
bs->private = &s->vdev.pci_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;
}