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qemu-e2k/hw/block/dataplane/xen-block.c

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/*
* Copyright (c) 2018 Citrix Systems Inc.
* (c) Gerd Hoffmann <kraxel@redhat.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; under version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, see <http://www.gnu.org/licenses/>.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include "qemu/osdep.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "hw/hw.h"
#include "hw/xen/xen_common.h"
#include "hw/block/xen_blkif.h"
#include "sysemu/block-backend.h"
#include "sysemu/iothread.h"
#include "xen-block.h"
struct ioreq {
blkif_request_t req;
int16_t status;
off_t start;
QEMUIOVector v;
void *buf;
size_t size;
int presync;
int aio_inflight;
int aio_errors;
struct XenBlkDev *blkdev;
QLIST_ENTRY(ioreq) list;
BlockAcctCookie acct;
};
struct XenBlkDev {
XenDevice *xendev;
XenEventChannel *event_channel;
unsigned int *ring_ref;
unsigned int nr_ring_ref;
void *sring;
int64_t file_blk;
int64_t file_size;
int protocol;
blkif_back_rings_t rings;
int more_work;
QLIST_HEAD(inflight_head, ioreq) inflight;
QLIST_HEAD(finished_head, ioreq) finished;
QLIST_HEAD(freelist_head, ioreq) freelist;
int requests_total;
int requests_inflight;
int requests_finished;
unsigned int max_requests;
BlockBackend *blk;
QEMUBH *bh;
IOThread *iothread;
AioContext *ctx;
};
static void ioreq_reset(struct ioreq *ioreq)
{
memset(&ioreq->req, 0, sizeof(ioreq->req));
ioreq->status = 0;
ioreq->start = 0;
ioreq->buf = NULL;
ioreq->size = 0;
ioreq->presync = 0;
ioreq->aio_inflight = 0;
ioreq->aio_errors = 0;
ioreq->blkdev = NULL;
memset(&ioreq->list, 0, sizeof(ioreq->list));
memset(&ioreq->acct, 0, sizeof(ioreq->acct));
qemu_iovec_reset(&ioreq->v);
}
static struct ioreq *ioreq_start(struct XenBlkDev *blkdev)
{
struct ioreq *ioreq = NULL;
if (QLIST_EMPTY(&blkdev->freelist)) {
if (blkdev->requests_total >= blkdev->max_requests) {
goto out;
}
/* allocate new struct */
ioreq = g_malloc0(sizeof(*ioreq));
ioreq->blkdev = blkdev;
blkdev->requests_total++;
qemu_iovec_init(&ioreq->v, 1);
} else {
/* get one from freelist */
ioreq = QLIST_FIRST(&blkdev->freelist);
QLIST_REMOVE(ioreq, list);
}
QLIST_INSERT_HEAD(&blkdev->inflight, ioreq, list);
blkdev->requests_inflight++;
out:
return ioreq;
}
static void ioreq_finish(struct ioreq *ioreq)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
QLIST_REMOVE(ioreq, list);
QLIST_INSERT_HEAD(&blkdev->finished, ioreq, list);
blkdev->requests_inflight--;
blkdev->requests_finished++;
}
static void ioreq_release(struct ioreq *ioreq, bool finish)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
QLIST_REMOVE(ioreq, list);
ioreq_reset(ioreq);
ioreq->blkdev = blkdev;
QLIST_INSERT_HEAD(&blkdev->freelist, ioreq, list);
if (finish) {
blkdev->requests_finished--;
} else {
blkdev->requests_inflight--;
}
}
/*
* translate request into iovec + start offset
* do sanity checks along the way
*/
static int ioreq_parse(struct ioreq *ioreq)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
size_t len;
int i;
switch (ioreq->req.operation) {
case BLKIF_OP_READ:
break;
case BLKIF_OP_FLUSH_DISKCACHE:
ioreq->presync = 1;
if (!ioreq->req.nr_segments) {
return 0;
}
/* fall through */
case BLKIF_OP_WRITE:
break;
case BLKIF_OP_DISCARD:
return 0;
default:
error_report("error: unknown operation (%d)", ioreq->req.operation);
goto err;
};
if (ioreq->req.operation != BLKIF_OP_READ &&
blk_is_read_only(blkdev->blk)) {
error_report("error: write req for ro device");
goto err;
}
ioreq->start = ioreq->req.sector_number * blkdev->file_blk;
for (i = 0; i < ioreq->req.nr_segments; i++) {
if (i == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
error_report("error: nr_segments too big");
goto err;
}
if (ioreq->req.seg[i].first_sect > ioreq->req.seg[i].last_sect) {
error_report("error: first > last sector");
goto err;
}
if (ioreq->req.seg[i].last_sect * blkdev->file_blk >= XC_PAGE_SIZE) {
error_report("error: page crossing");
goto err;
}
len = (ioreq->req.seg[i].last_sect -
ioreq->req.seg[i].first_sect + 1) * blkdev->file_blk;
ioreq->size += len;
}
if (ioreq->start + ioreq->size > blkdev->file_size) {
error_report("error: access beyond end of file");
goto err;
}
return 0;
err:
ioreq->status = BLKIF_RSP_ERROR;
return -1;
}
static int ioreq_grant_copy(struct ioreq *ioreq)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
XenDevice *xendev = blkdev->xendev;
XenDeviceGrantCopySegment segs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
int i, count;
int64_t file_blk = blkdev->file_blk;
bool to_domain = (ioreq->req.operation == BLKIF_OP_READ);
void *virt = ioreq->buf;
Error *local_err = NULL;
if (ioreq->req.nr_segments == 0) {
return 0;
}
count = ioreq->req.nr_segments;
for (i = 0; i < count; i++) {
if (to_domain) {
segs[i].dest.foreign.ref = ioreq->req.seg[i].gref;
segs[i].dest.foreign.offset = ioreq->req.seg[i].first_sect *
file_blk;
segs[i].source.virt = virt;
} else {
segs[i].source.foreign.ref = ioreq->req.seg[i].gref;
segs[i].source.foreign.offset = ioreq->req.seg[i].first_sect *
file_blk;
segs[i].dest.virt = virt;
}
segs[i].len = (ioreq->req.seg[i].last_sect -
ioreq->req.seg[i].first_sect + 1) * file_blk;
virt += segs[i].len;
}
xen_device_copy_grant_refs(xendev, to_domain, segs, count, &local_err);
if (local_err) {
error_reportf_err(local_err, "failed to copy data: ");
ioreq->aio_errors++;
return -1;
}
return 0;
}
static int ioreq_runio_qemu_aio(struct ioreq *ioreq);
static void qemu_aio_complete(void *opaque, int ret)
{
struct ioreq *ioreq = opaque;
struct XenBlkDev *blkdev = ioreq->blkdev;
aio_context_acquire(blkdev->ctx);
if (ret != 0) {
error_report("%s I/O error",
ioreq->req.operation == BLKIF_OP_READ ?
"read" : "write");
ioreq->aio_errors++;
}
ioreq->aio_inflight--;
if (ioreq->presync) {
ioreq->presync = 0;
ioreq_runio_qemu_aio(ioreq);
goto done;
}
if (ioreq->aio_inflight > 0) {
goto done;
}
switch (ioreq->req.operation) {
case BLKIF_OP_READ:
/* in case of failure ioreq->aio_errors is increased */
if (ret == 0) {
ioreq_grant_copy(ioreq);
}
qemu_vfree(ioreq->buf);
break;
case BLKIF_OP_WRITE:
case BLKIF_OP_FLUSH_DISKCACHE:
if (!ioreq->req.nr_segments) {
break;
}
qemu_vfree(ioreq->buf);
break;
default:
break;
}
ioreq->status = ioreq->aio_errors ? BLKIF_RSP_ERROR : BLKIF_RSP_OKAY;
ioreq_finish(ioreq);
switch (ioreq->req.operation) {
case BLKIF_OP_WRITE:
case BLKIF_OP_FLUSH_DISKCACHE:
if (!ioreq->req.nr_segments) {
break;
}
case BLKIF_OP_READ:
if (ioreq->status == BLKIF_RSP_OKAY) {
block_acct_done(blk_get_stats(blkdev->blk), &ioreq->acct);
} else {
block_acct_failed(blk_get_stats(blkdev->blk), &ioreq->acct);
}
break;
case BLKIF_OP_DISCARD:
default:
break;
}
qemu_bh_schedule(blkdev->bh);
done:
aio_context_release(blkdev->ctx);
}
static bool blk_split_discard(struct ioreq *ioreq, blkif_sector_t sector_number,
uint64_t nr_sectors)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
int64_t byte_offset;
int byte_chunk;
uint64_t byte_remaining, limit;
uint64_t sec_start = sector_number;
uint64_t sec_count = nr_sectors;
/* Wrap around, or overflowing byte limit? */
if (sec_start + sec_count < sec_count ||
sec_start + sec_count > INT64_MAX / blkdev->file_blk) {
return false;
}
limit = BDRV_REQUEST_MAX_SECTORS * blkdev->file_blk;
byte_offset = sec_start * blkdev->file_blk;
byte_remaining = sec_count * blkdev->file_blk;
do {
byte_chunk = byte_remaining > limit ? limit : byte_remaining;
ioreq->aio_inflight++;
blk_aio_pdiscard(blkdev->blk, byte_offset, byte_chunk,
qemu_aio_complete, ioreq);
byte_remaining -= byte_chunk;
byte_offset += byte_chunk;
} while (byte_remaining > 0);
return true;
}
static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
ioreq->buf = qemu_memalign(XC_PAGE_SIZE, ioreq->size);
if (ioreq->req.nr_segments &&
(ioreq->req.operation == BLKIF_OP_WRITE ||
ioreq->req.operation == BLKIF_OP_FLUSH_DISKCACHE) &&
ioreq_grant_copy(ioreq)) {
qemu_vfree(ioreq->buf);
goto err;
}
ioreq->aio_inflight++;
if (ioreq->presync) {
blk_aio_flush(ioreq->blkdev->blk, qemu_aio_complete, ioreq);
return 0;
}
switch (ioreq->req.operation) {
case BLKIF_OP_READ:
qemu_iovec_add(&ioreq->v, ioreq->buf, ioreq->size);
block_acct_start(blk_get_stats(blkdev->blk), &ioreq->acct,
ioreq->v.size, BLOCK_ACCT_READ);
ioreq->aio_inflight++;
blk_aio_preadv(blkdev->blk, ioreq->start, &ioreq->v, 0,
qemu_aio_complete, ioreq);
break;
case BLKIF_OP_WRITE:
case BLKIF_OP_FLUSH_DISKCACHE:
if (!ioreq->req.nr_segments) {
break;
}
qemu_iovec_add(&ioreq->v, ioreq->buf, ioreq->size);
block_acct_start(blk_get_stats(blkdev->blk), &ioreq->acct,
ioreq->v.size,
ioreq->req.operation == BLKIF_OP_WRITE ?
BLOCK_ACCT_WRITE : BLOCK_ACCT_FLUSH);
ioreq->aio_inflight++;
blk_aio_pwritev(blkdev->blk, ioreq->start, &ioreq->v, 0,
qemu_aio_complete, ioreq);
break;
case BLKIF_OP_DISCARD:
{
struct blkif_request_discard *req = (void *)&ioreq->req;
if (!blk_split_discard(ioreq, req->sector_number, req->nr_sectors)) {
goto err;
}
break;
}
default:
/* unknown operation (shouldn't happen -- parse catches this) */
goto err;
}
qemu_aio_complete(ioreq, 0);
return 0;
err:
ioreq_finish(ioreq);
ioreq->status = BLKIF_RSP_ERROR;
return -1;
}
static int blk_send_response_one(struct ioreq *ioreq)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
int send_notify = 0;
int have_requests = 0;
blkif_response_t *resp;
/* Place on the response ring for the relevant domain. */
switch (blkdev->protocol) {
case BLKIF_PROTOCOL_NATIVE:
resp = (blkif_response_t *)RING_GET_RESPONSE(
&blkdev->rings.native,
blkdev->rings.native.rsp_prod_pvt);
break;
case BLKIF_PROTOCOL_X86_32:
resp = (blkif_response_t *)RING_GET_RESPONSE(
&blkdev->rings.x86_32_part,
blkdev->rings.x86_32_part.rsp_prod_pvt);
break;
case BLKIF_PROTOCOL_X86_64:
resp = (blkif_response_t *)RING_GET_RESPONSE(
&blkdev->rings.x86_64_part,
blkdev->rings.x86_64_part.rsp_prod_pvt);
break;
default:
return 0;
}
resp->id = ioreq->req.id;
resp->operation = ioreq->req.operation;
resp->status = ioreq->status;
blkdev->rings.common.rsp_prod_pvt++;
RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blkdev->rings.common, send_notify);
if (blkdev->rings.common.rsp_prod_pvt == blkdev->rings.common.req_cons) {
/*
* Tail check for pending requests. Allows frontend to avoid
* notifications if requests are already in flight (lower
* overheads and promotes batching).
*/
RING_FINAL_CHECK_FOR_REQUESTS(&blkdev->rings.common, have_requests);
} else if (RING_HAS_UNCONSUMED_REQUESTS(&blkdev->rings.common)) {
have_requests = 1;
}
if (have_requests) {
blkdev->more_work++;
}
return send_notify;
}
/* walk finished list, send outstanding responses, free requests */
static void blk_send_response_all(struct XenBlkDev *blkdev)
{
struct ioreq *ioreq;
int send_notify = 0;
while (!QLIST_EMPTY(&blkdev->finished)) {
ioreq = QLIST_FIRST(&blkdev->finished);
send_notify += blk_send_response_one(ioreq);
ioreq_release(ioreq, true);
}
if (send_notify) {
Error *local_err = NULL;
xen_device_notify_event_channel(blkdev->xendev,
blkdev->event_channel,
&local_err);
if (local_err) {
error_report_err(local_err);
}
}
}
static int blk_get_request(struct XenBlkDev *blkdev, struct ioreq *ioreq,
RING_IDX rc)
{
switch (blkdev->protocol) {
case BLKIF_PROTOCOL_NATIVE:
memcpy(&ioreq->req, RING_GET_REQUEST(&blkdev->rings.native, rc),
sizeof(ioreq->req));
break;
case BLKIF_PROTOCOL_X86_32:
blkif_get_x86_32_req(&ioreq->req,
RING_GET_REQUEST(&blkdev->rings.x86_32_part, rc));
break;
case BLKIF_PROTOCOL_X86_64:
blkif_get_x86_64_req(&ioreq->req,
RING_GET_REQUEST(&blkdev->rings.x86_64_part, rc));
break;
}
/* Prevent the compiler from accessing the on-ring fields instead. */
barrier();
return 0;
}
static void blk_handle_requests(struct XenBlkDev *blkdev)
{
RING_IDX rc, rp;
struct ioreq *ioreq;
blkdev->more_work = 0;
rc = blkdev->rings.common.req_cons;
rp = blkdev->rings.common.sring->req_prod;
xen_rmb(); /* Ensure we see queued requests up to 'rp'. */
blk_send_response_all(blkdev);
while (rc != rp) {
/* pull request from ring */
if (RING_REQUEST_CONS_OVERFLOW(&blkdev->rings.common, rc)) {
break;
}
ioreq = ioreq_start(blkdev);
if (ioreq == NULL) {
blkdev->more_work++;
break;
}
blk_get_request(blkdev, ioreq, rc);
blkdev->rings.common.req_cons = ++rc;
/* parse them */
if (ioreq_parse(ioreq) != 0) {
switch (ioreq->req.operation) {
case BLKIF_OP_READ:
block_acct_invalid(blk_get_stats(blkdev->blk),
BLOCK_ACCT_READ);
break;
case BLKIF_OP_WRITE:
block_acct_invalid(blk_get_stats(blkdev->blk),
BLOCK_ACCT_WRITE);
break;
case BLKIF_OP_FLUSH_DISKCACHE:
block_acct_invalid(blk_get_stats(blkdev->blk),
BLOCK_ACCT_FLUSH);
default:
break;
};
if (blk_send_response_one(ioreq)) {
Error *local_err = NULL;
xen_device_notify_event_channel(blkdev->xendev,
blkdev->event_channel,
&local_err);
if (local_err) {
error_report_err(local_err);
}
}
ioreq_release(ioreq, false);
continue;
}
ioreq_runio_qemu_aio(ioreq);
}
if (blkdev->more_work && blkdev->requests_inflight < blkdev->max_requests) {
qemu_bh_schedule(blkdev->bh);
}
}
static void blk_bh(void *opaque)
{
struct XenBlkDev *blkdev = opaque;
aio_context_acquire(blkdev->ctx);
blk_handle_requests(blkdev);
aio_context_release(blkdev->ctx);
}
static void blk_event(void *opaque)
{
struct XenBlkDev *blkdev = opaque;
qemu_bh_schedule(blkdev->bh);
}
struct XenBlkDev *xen_block_dataplane_create(XenDevice *xendev,
BlockConf *conf,
IOThread *iothread)
{
struct XenBlkDev *blkdev = g_new0(struct XenBlkDev, 1);
blkdev->xendev = xendev;
blkdev->file_blk = conf->logical_block_size;
blkdev->blk = conf->blk;
blkdev->file_size = blk_getlength(blkdev->blk);
QLIST_INIT(&blkdev->inflight);
QLIST_INIT(&blkdev->finished);
QLIST_INIT(&blkdev->freelist);
if (iothread) {
blkdev->iothread = iothread;
object_ref(OBJECT(blkdev->iothread));
blkdev->ctx = iothread_get_aio_context(blkdev->iothread);
} else {
blkdev->ctx = qemu_get_aio_context();
}
blkdev->bh = aio_bh_new(blkdev->ctx, blk_bh, blkdev);
return blkdev;
}
void xen_block_dataplane_destroy(struct XenBlkDev *blkdev)
{
struct ioreq *ioreq;
if (!blkdev) {
return;
}
while (!QLIST_EMPTY(&blkdev->freelist)) {
ioreq = QLIST_FIRST(&blkdev->freelist);
QLIST_REMOVE(ioreq, list);
qemu_iovec_destroy(&ioreq->v);
g_free(ioreq);
}
qemu_bh_delete(blkdev->bh);
if (blkdev->iothread) {
object_unref(OBJECT(blkdev->iothread));
}
g_free(blkdev);
}
void xen_block_dataplane_stop(struct XenBlkDev *blkdev)
{
XenDevice *xendev;
if (!blkdev) {
return;
}
aio_context_acquire(blkdev->ctx);
blk_set_aio_context(blkdev->blk, qemu_get_aio_context());
aio_context_release(blkdev->ctx);
xendev = blkdev->xendev;
if (blkdev->event_channel) {
Error *local_err = NULL;
xen_device_unbind_event_channel(xendev, blkdev->event_channel,
&local_err);
blkdev->event_channel = NULL;
if (local_err) {
error_report_err(local_err);
}
}
if (blkdev->sring) {
Error *local_err = NULL;
xen_device_unmap_grant_refs(xendev, blkdev->sring,
blkdev->nr_ring_ref, &local_err);
blkdev->sring = NULL;
if (local_err) {
error_report_err(local_err);
}
}
g_free(blkdev->ring_ref);
blkdev->ring_ref = NULL;
}
void xen_block_dataplane_start(struct XenBlkDev *blkdev,
const unsigned int ring_ref[],
unsigned int nr_ring_ref,
unsigned int event_channel,
unsigned int protocol,
Error **errp)
{
XenDevice *xendev = blkdev->xendev;
Error *local_err = NULL;
unsigned int ring_size;
unsigned int i;
blkdev->nr_ring_ref = nr_ring_ref;
blkdev->ring_ref = g_new(unsigned int, nr_ring_ref);
for (i = 0; i < nr_ring_ref; i++) {
blkdev->ring_ref[i] = ring_ref[i];
}
blkdev->protocol = protocol;
ring_size = XC_PAGE_SIZE * blkdev->nr_ring_ref;
switch (blkdev->protocol) {
case BLKIF_PROTOCOL_NATIVE:
{
blkdev->max_requests = __CONST_RING_SIZE(blkif, ring_size);
break;
}
case BLKIF_PROTOCOL_X86_32:
{
blkdev->max_requests = __CONST_RING_SIZE(blkif_x86_32, ring_size);
break;
}
case BLKIF_PROTOCOL_X86_64:
{
blkdev->max_requests = __CONST_RING_SIZE(blkif_x86_64, ring_size);
break;
}
default:
error_setg(errp, "unknown protocol %u", blkdev->protocol);
return;
}
xen_device_set_max_grant_refs(xendev, blkdev->nr_ring_ref,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
goto stop;
}
blkdev->sring = xen_device_map_grant_refs(xendev,
blkdev->ring_ref,
blkdev->nr_ring_ref,
PROT_READ | PROT_WRITE,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
goto stop;
}
switch (blkdev->protocol) {
case BLKIF_PROTOCOL_NATIVE:
{
blkif_sring_t *sring_native = blkdev->sring;
BACK_RING_INIT(&blkdev->rings.native, sring_native, ring_size);
break;
}
case BLKIF_PROTOCOL_X86_32:
{
blkif_x86_32_sring_t *sring_x86_32 = blkdev->sring;
BACK_RING_INIT(&blkdev->rings.x86_32_part, sring_x86_32,
ring_size);
break;
}
case BLKIF_PROTOCOL_X86_64:
{
blkif_x86_64_sring_t *sring_x86_64 = blkdev->sring;
BACK_RING_INIT(&blkdev->rings.x86_64_part, sring_x86_64,
ring_size);
break;
}
}
blkdev->event_channel =
xen_device_bind_event_channel(xendev, event_channel,
blk_event, blkdev,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
goto stop;
}
aio_context_acquire(blkdev->ctx);
blk_set_aio_context(blkdev->blk, blkdev->ctx);
aio_context_release(blkdev->ctx);
return;
stop:
xen_block_dataplane_stop(blkdev);
}
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