518 lines
16 KiB
C
518 lines
16 KiB
C
/*
|
|
* Dedicated thread for virtio-blk I/O processing
|
|
*
|
|
* Copyright 2012 IBM, Corp.
|
|
* Copyright 2012 Red Hat, Inc. and/or its affiliates
|
|
*
|
|
* Authors:
|
|
* Stefan Hajnoczi <stefanha@redhat.com>
|
|
*
|
|
* This work is licensed under the terms of the GNU GPL, version 2 or later.
|
|
* See the COPYING file in the top-level directory.
|
|
*
|
|
*/
|
|
|
|
#include "trace.h"
|
|
#include "qemu/iov.h"
|
|
#include "event-poll.h"
|
|
#include "qemu/thread.h"
|
|
#include "vring.h"
|
|
#include "ioq.h"
|
|
#include "migration/migration.h"
|
|
#include "hw/virtio-blk.h"
|
|
#include "hw/dataplane/virtio-blk.h"
|
|
|
|
enum {
|
|
SEG_MAX = 126, /* maximum number of I/O segments */
|
|
VRING_MAX = SEG_MAX + 2, /* maximum number of vring descriptors */
|
|
REQ_MAX = VRING_MAX, /* maximum number of requests in the vring,
|
|
* is VRING_MAX / 2 with traditional and
|
|
* VRING_MAX with indirect descriptors */
|
|
};
|
|
|
|
typedef struct {
|
|
struct iocb iocb; /* Linux AIO control block */
|
|
QEMUIOVector *inhdr; /* iovecs for virtio_blk_inhdr */
|
|
unsigned int head; /* vring descriptor index */
|
|
struct iovec *bounce_iov; /* used if guest buffers are unaligned */
|
|
QEMUIOVector *read_qiov; /* for read completion /w bounce buffer */
|
|
} VirtIOBlockRequest;
|
|
|
|
struct VirtIOBlockDataPlane {
|
|
bool started;
|
|
bool stopping;
|
|
QEMUBH *start_bh;
|
|
QemuThread thread;
|
|
|
|
VirtIOBlkConf *blk;
|
|
int fd; /* image file descriptor */
|
|
|
|
VirtIODevice *vdev;
|
|
Vring vring; /* virtqueue vring */
|
|
EventNotifier *guest_notifier; /* irq */
|
|
|
|
EventPoll event_poll; /* event poller */
|
|
EventHandler io_handler; /* Linux AIO completion handler */
|
|
EventHandler notify_handler; /* virtqueue notify handler */
|
|
|
|
IOQueue ioqueue; /* Linux AIO queue (should really be per
|
|
dataplane thread) */
|
|
VirtIOBlockRequest requests[REQ_MAX]; /* pool of requests, managed by the
|
|
queue */
|
|
|
|
unsigned int num_reqs;
|
|
|
|
Error *migration_blocker;
|
|
};
|
|
|
|
/* Raise an interrupt to signal guest, if necessary */
|
|
static void notify_guest(VirtIOBlockDataPlane *s)
|
|
{
|
|
if (!vring_should_notify(s->vdev, &s->vring)) {
|
|
return;
|
|
}
|
|
|
|
event_notifier_set(s->guest_notifier);
|
|
}
|
|
|
|
static void complete_request(struct iocb *iocb, ssize_t ret, void *opaque)
|
|
{
|
|
VirtIOBlockDataPlane *s = opaque;
|
|
VirtIOBlockRequest *req = container_of(iocb, VirtIOBlockRequest, iocb);
|
|
struct virtio_blk_inhdr hdr;
|
|
int len;
|
|
|
|
if (likely(ret >= 0)) {
|
|
hdr.status = VIRTIO_BLK_S_OK;
|
|
len = ret;
|
|
} else {
|
|
hdr.status = VIRTIO_BLK_S_IOERR;
|
|
len = 0;
|
|
}
|
|
|
|
trace_virtio_blk_data_plane_complete_request(s, req->head, ret);
|
|
|
|
if (req->read_qiov) {
|
|
assert(req->bounce_iov);
|
|
qemu_iovec_from_buf(req->read_qiov, 0, req->bounce_iov->iov_base, len);
|
|
qemu_iovec_destroy(req->read_qiov);
|
|
g_slice_free(QEMUIOVector, req->read_qiov);
|
|
}
|
|
|
|
if (req->bounce_iov) {
|
|
qemu_vfree(req->bounce_iov->iov_base);
|
|
g_slice_free(struct iovec, req->bounce_iov);
|
|
}
|
|
|
|
qemu_iovec_from_buf(req->inhdr, 0, &hdr, sizeof(hdr));
|
|
qemu_iovec_destroy(req->inhdr);
|
|
g_slice_free(QEMUIOVector, req->inhdr);
|
|
|
|
/* According to the virtio specification len should be the number of bytes
|
|
* written to, but for virtio-blk it seems to be the number of bytes
|
|
* transferred plus the status bytes.
|
|
*/
|
|
vring_push(&s->vring, req->head, len + sizeof(hdr));
|
|
|
|
s->num_reqs--;
|
|
}
|
|
|
|
static void complete_request_early(VirtIOBlockDataPlane *s, unsigned int head,
|
|
QEMUIOVector *inhdr, unsigned char status)
|
|
{
|
|
struct virtio_blk_inhdr hdr = {
|
|
.status = status,
|
|
};
|
|
|
|
qemu_iovec_from_buf(inhdr, 0, &hdr, sizeof(hdr));
|
|
qemu_iovec_destroy(inhdr);
|
|
g_slice_free(QEMUIOVector, inhdr);
|
|
|
|
vring_push(&s->vring, head, sizeof(hdr));
|
|
notify_guest(s);
|
|
}
|
|
|
|
/* Get disk serial number */
|
|
static void do_get_id_cmd(VirtIOBlockDataPlane *s,
|
|
struct iovec *iov, unsigned int iov_cnt,
|
|
unsigned int head, QEMUIOVector *inhdr)
|
|
{
|
|
char id[VIRTIO_BLK_ID_BYTES];
|
|
|
|
/* Serial number not NUL-terminated when shorter than buffer */
|
|
strncpy(id, s->blk->serial ? s->blk->serial : "", sizeof(id));
|
|
iov_from_buf(iov, iov_cnt, 0, id, sizeof(id));
|
|
complete_request_early(s, head, inhdr, VIRTIO_BLK_S_OK);
|
|
}
|
|
|
|
static int do_rdwr_cmd(VirtIOBlockDataPlane *s, bool read,
|
|
struct iovec *iov, unsigned int iov_cnt,
|
|
long long offset, unsigned int head,
|
|
QEMUIOVector *inhdr)
|
|
{
|
|
struct iocb *iocb;
|
|
QEMUIOVector qiov;
|
|
struct iovec *bounce_iov = NULL;
|
|
QEMUIOVector *read_qiov = NULL;
|
|
|
|
qemu_iovec_init_external(&qiov, iov, iov_cnt);
|
|
if (!bdrv_qiov_is_aligned(s->blk->conf.bs, &qiov)) {
|
|
void *bounce_buffer = qemu_blockalign(s->blk->conf.bs, qiov.size);
|
|
|
|
if (read) {
|
|
/* Need to copy back from bounce buffer on completion */
|
|
read_qiov = g_slice_new(QEMUIOVector);
|
|
qemu_iovec_init(read_qiov, iov_cnt);
|
|
qemu_iovec_concat_iov(read_qiov, iov, iov_cnt, 0, qiov.size);
|
|
} else {
|
|
qemu_iovec_to_buf(&qiov, 0, bounce_buffer, qiov.size);
|
|
}
|
|
|
|
/* Redirect I/O to aligned bounce buffer */
|
|
bounce_iov = g_slice_new(struct iovec);
|
|
bounce_iov->iov_base = bounce_buffer;
|
|
bounce_iov->iov_len = qiov.size;
|
|
iov = bounce_iov;
|
|
iov_cnt = 1;
|
|
}
|
|
|
|
iocb = ioq_rdwr(&s->ioqueue, read, iov, iov_cnt, offset);
|
|
|
|
/* Fill in virtio block metadata needed for completion */
|
|
VirtIOBlockRequest *req = container_of(iocb, VirtIOBlockRequest, iocb);
|
|
req->head = head;
|
|
req->inhdr = inhdr;
|
|
req->bounce_iov = bounce_iov;
|
|
req->read_qiov = read_qiov;
|
|
return 0;
|
|
}
|
|
|
|
static int process_request(IOQueue *ioq, struct iovec iov[],
|
|
unsigned int out_num, unsigned int in_num,
|
|
unsigned int head)
|
|
{
|
|
VirtIOBlockDataPlane *s = container_of(ioq, VirtIOBlockDataPlane, ioqueue);
|
|
struct iovec *in_iov = &iov[out_num];
|
|
struct virtio_blk_outhdr outhdr;
|
|
QEMUIOVector *inhdr;
|
|
size_t in_size;
|
|
|
|
/* Copy in outhdr */
|
|
if (unlikely(iov_to_buf(iov, out_num, 0, &outhdr,
|
|
sizeof(outhdr)) != sizeof(outhdr))) {
|
|
error_report("virtio-blk request outhdr too short");
|
|
return -EFAULT;
|
|
}
|
|
iov_discard_front(&iov, &out_num, sizeof(outhdr));
|
|
|
|
/* Grab inhdr for later */
|
|
in_size = iov_size(in_iov, in_num);
|
|
if (in_size < sizeof(struct virtio_blk_inhdr)) {
|
|
error_report("virtio_blk request inhdr too short");
|
|
return -EFAULT;
|
|
}
|
|
inhdr = g_slice_new(QEMUIOVector);
|
|
qemu_iovec_init(inhdr, 1);
|
|
qemu_iovec_concat_iov(inhdr, in_iov, in_num,
|
|
in_size - sizeof(struct virtio_blk_inhdr),
|
|
sizeof(struct virtio_blk_inhdr));
|
|
iov_discard_back(in_iov, &in_num, sizeof(struct virtio_blk_inhdr));
|
|
|
|
/* TODO Linux sets the barrier bit even when not advertised! */
|
|
outhdr.type &= ~VIRTIO_BLK_T_BARRIER;
|
|
|
|
switch (outhdr.type) {
|
|
case VIRTIO_BLK_T_IN:
|
|
do_rdwr_cmd(s, true, in_iov, in_num, outhdr.sector * 512, head, inhdr);
|
|
return 0;
|
|
|
|
case VIRTIO_BLK_T_OUT:
|
|
do_rdwr_cmd(s, false, iov, out_num, outhdr.sector * 512, head, inhdr);
|
|
return 0;
|
|
|
|
case VIRTIO_BLK_T_SCSI_CMD:
|
|
/* TODO support SCSI commands */
|
|
complete_request_early(s, head, inhdr, VIRTIO_BLK_S_UNSUPP);
|
|
return 0;
|
|
|
|
case VIRTIO_BLK_T_FLUSH:
|
|
/* TODO fdsync not supported by Linux AIO, do it synchronously here! */
|
|
if (qemu_fdatasync(s->fd) < 0) {
|
|
complete_request_early(s, head, inhdr, VIRTIO_BLK_S_IOERR);
|
|
} else {
|
|
complete_request_early(s, head, inhdr, VIRTIO_BLK_S_OK);
|
|
}
|
|
return 0;
|
|
|
|
case VIRTIO_BLK_T_GET_ID:
|
|
do_get_id_cmd(s, in_iov, in_num, head, inhdr);
|
|
return 0;
|
|
|
|
default:
|
|
error_report("virtio-blk unsupported request type %#x", outhdr.type);
|
|
qemu_iovec_destroy(inhdr);
|
|
g_slice_free(QEMUIOVector, inhdr);
|
|
return -EFAULT;
|
|
}
|
|
}
|
|
|
|
static void handle_notify(EventHandler *handler)
|
|
{
|
|
VirtIOBlockDataPlane *s = container_of(handler, VirtIOBlockDataPlane,
|
|
notify_handler);
|
|
|
|
/* There is one array of iovecs into which all new requests are extracted
|
|
* from the vring. Requests are read from the vring and the translated
|
|
* descriptors are written to the iovecs array. The iovecs do not have to
|
|
* persist across handle_notify() calls because the kernel copies the
|
|
* iovecs on io_submit().
|
|
*
|
|
* Handling io_submit() EAGAIN may require storing the requests across
|
|
* handle_notify() calls until the kernel has sufficient resources to
|
|
* accept more I/O. This is not implemented yet.
|
|
*/
|
|
struct iovec iovec[VRING_MAX];
|
|
struct iovec *end = &iovec[VRING_MAX];
|
|
struct iovec *iov = iovec;
|
|
|
|
/* When a request is read from the vring, the index of the first descriptor
|
|
* (aka head) is returned so that the completed request can be pushed onto
|
|
* the vring later.
|
|
*
|
|
* The number of hypervisor read-only iovecs is out_num. The number of
|
|
* hypervisor write-only iovecs is in_num.
|
|
*/
|
|
int head;
|
|
unsigned int out_num = 0, in_num = 0;
|
|
unsigned int num_queued;
|
|
|
|
for (;;) {
|
|
/* Disable guest->host notifies to avoid unnecessary vmexits */
|
|
vring_disable_notification(s->vdev, &s->vring);
|
|
|
|
for (;;) {
|
|
head = vring_pop(s->vdev, &s->vring, iov, end, &out_num, &in_num);
|
|
if (head < 0) {
|
|
break; /* no more requests */
|
|
}
|
|
|
|
trace_virtio_blk_data_plane_process_request(s, out_num, in_num,
|
|
head);
|
|
|
|
if (process_request(&s->ioqueue, iov, out_num, in_num, head) < 0) {
|
|
vring_set_broken(&s->vring);
|
|
break;
|
|
}
|
|
iov += out_num + in_num;
|
|
}
|
|
|
|
if (likely(head == -EAGAIN)) { /* vring emptied */
|
|
/* Re-enable guest->host notifies and stop processing the vring.
|
|
* But if the guest has snuck in more descriptors, keep processing.
|
|
*/
|
|
if (vring_enable_notification(s->vdev, &s->vring)) {
|
|
break;
|
|
}
|
|
} else { /* head == -ENOBUFS or fatal error, iovecs[] is depleted */
|
|
/* Since there are no iovecs[] left, stop processing for now. Do
|
|
* not re-enable guest->host notifies since the I/O completion
|
|
* handler knows to check for more vring descriptors anyway.
|
|
*/
|
|
break;
|
|
}
|
|
}
|
|
|
|
num_queued = ioq_num_queued(&s->ioqueue);
|
|
if (num_queued > 0) {
|
|
s->num_reqs += num_queued;
|
|
|
|
int rc = ioq_submit(&s->ioqueue);
|
|
if (unlikely(rc < 0)) {
|
|
fprintf(stderr, "ioq_submit failed %d\n", rc);
|
|
exit(1);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void handle_io(EventHandler *handler)
|
|
{
|
|
VirtIOBlockDataPlane *s = container_of(handler, VirtIOBlockDataPlane,
|
|
io_handler);
|
|
|
|
if (ioq_run_completion(&s->ioqueue, complete_request, s) > 0) {
|
|
notify_guest(s);
|
|
}
|
|
|
|
/* If there were more requests than iovecs, the vring will not be empty yet
|
|
* so check again. There should now be enough resources to process more
|
|
* requests.
|
|
*/
|
|
if (unlikely(vring_more_avail(&s->vring))) {
|
|
handle_notify(&s->notify_handler);
|
|
}
|
|
}
|
|
|
|
static void *data_plane_thread(void *opaque)
|
|
{
|
|
VirtIOBlockDataPlane *s = opaque;
|
|
|
|
do {
|
|
event_poll(&s->event_poll);
|
|
} while (!s->stopping || s->num_reqs > 0);
|
|
return NULL;
|
|
}
|
|
|
|
static void start_data_plane_bh(void *opaque)
|
|
{
|
|
VirtIOBlockDataPlane *s = opaque;
|
|
|
|
qemu_bh_delete(s->start_bh);
|
|
s->start_bh = NULL;
|
|
qemu_thread_create(&s->thread, data_plane_thread,
|
|
s, QEMU_THREAD_JOINABLE);
|
|
}
|
|
|
|
bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
|
|
VirtIOBlockDataPlane **dataplane)
|
|
{
|
|
VirtIOBlockDataPlane *s;
|
|
int fd;
|
|
|
|
*dataplane = NULL;
|
|
|
|
if (!blk->data_plane) {
|
|
return true;
|
|
}
|
|
|
|
if (blk->scsi) {
|
|
error_report("device is incompatible with x-data-plane, use scsi=off");
|
|
return false;
|
|
}
|
|
|
|
if (blk->config_wce) {
|
|
error_report("device is incompatible with x-data-plane, "
|
|
"use config-wce=off");
|
|
return false;
|
|
}
|
|
|
|
fd = raw_get_aio_fd(blk->conf.bs);
|
|
if (fd < 0) {
|
|
error_report("drive is incompatible with x-data-plane, "
|
|
"use format=raw,cache=none,aio=native");
|
|
return false;
|
|
}
|
|
|
|
s = g_new0(VirtIOBlockDataPlane, 1);
|
|
s->vdev = vdev;
|
|
s->fd = fd;
|
|
s->blk = blk;
|
|
|
|
/* Prevent block operations that conflict with data plane thread */
|
|
bdrv_set_in_use(blk->conf.bs, 1);
|
|
|
|
error_setg(&s->migration_blocker,
|
|
"x-data-plane does not support migration");
|
|
migrate_add_blocker(s->migration_blocker);
|
|
|
|
*dataplane = s;
|
|
return true;
|
|
}
|
|
|
|
void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
|
|
{
|
|
if (!s) {
|
|
return;
|
|
}
|
|
|
|
virtio_blk_data_plane_stop(s);
|
|
migrate_del_blocker(s->migration_blocker);
|
|
error_free(s->migration_blocker);
|
|
bdrv_set_in_use(s->blk->conf.bs, 0);
|
|
g_free(s);
|
|
}
|
|
|
|
void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
|
|
{
|
|
VirtQueue *vq;
|
|
int i;
|
|
|
|
if (s->started) {
|
|
return;
|
|
}
|
|
|
|
vq = virtio_get_queue(s->vdev, 0);
|
|
if (!vring_setup(&s->vring, s->vdev, 0)) {
|
|
return;
|
|
}
|
|
|
|
event_poll_init(&s->event_poll);
|
|
|
|
/* Set up guest notifier (irq) */
|
|
if (s->vdev->binding->set_guest_notifiers(s->vdev->binding_opaque, 1,
|
|
true) != 0) {
|
|
fprintf(stderr, "virtio-blk failed to set guest notifier, "
|
|
"ensure -enable-kvm is set\n");
|
|
exit(1);
|
|
}
|
|
s->guest_notifier = virtio_queue_get_guest_notifier(vq);
|
|
|
|
/* Set up virtqueue notify */
|
|
if (s->vdev->binding->set_host_notifier(s->vdev->binding_opaque,
|
|
0, true) != 0) {
|
|
fprintf(stderr, "virtio-blk failed to set host notifier\n");
|
|
exit(1);
|
|
}
|
|
event_poll_add(&s->event_poll, &s->notify_handler,
|
|
virtio_queue_get_host_notifier(vq),
|
|
handle_notify);
|
|
|
|
/* Set up ioqueue */
|
|
ioq_init(&s->ioqueue, s->fd, REQ_MAX);
|
|
for (i = 0; i < ARRAY_SIZE(s->requests); i++) {
|
|
ioq_put_iocb(&s->ioqueue, &s->requests[i].iocb);
|
|
}
|
|
event_poll_add(&s->event_poll, &s->io_handler,
|
|
ioq_get_notifier(&s->ioqueue), handle_io);
|
|
|
|
s->started = true;
|
|
trace_virtio_blk_data_plane_start(s);
|
|
|
|
/* Kick right away to begin processing requests already in vring */
|
|
event_notifier_set(virtio_queue_get_host_notifier(vq));
|
|
|
|
/* Spawn thread in BH so it inherits iothread cpusets */
|
|
s->start_bh = qemu_bh_new(start_data_plane_bh, s);
|
|
qemu_bh_schedule(s->start_bh);
|
|
}
|
|
|
|
void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
|
|
{
|
|
if (!s->started || s->stopping) {
|
|
return;
|
|
}
|
|
s->stopping = true;
|
|
trace_virtio_blk_data_plane_stop(s);
|
|
|
|
/* Stop thread or cancel pending thread creation BH */
|
|
if (s->start_bh) {
|
|
qemu_bh_delete(s->start_bh);
|
|
s->start_bh = NULL;
|
|
} else {
|
|
event_poll_notify(&s->event_poll);
|
|
qemu_thread_join(&s->thread);
|
|
}
|
|
|
|
ioq_cleanup(&s->ioqueue);
|
|
|
|
s->vdev->binding->set_host_notifier(s->vdev->binding_opaque, 0, false);
|
|
|
|
event_poll_cleanup(&s->event_poll);
|
|
|
|
/* Clean up guest notifier (irq) */
|
|
s->vdev->binding->set_guest_notifiers(s->vdev->binding_opaque, 1, false);
|
|
|
|
vring_teardown(&s->vring);
|
|
s->started = false;
|
|
s->stopping = false;
|
|
}
|