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qemu/hw/block/xen_disk.c
Roger Pau Monne 2f01dfacb5 xen_disk: fix unmapping of persistent grants 
This patch fixes two issues with persistent grants and the disk PV backend
(Qdisk):

 - Keep track of memory regions where persistent grants have been mapped
   since we need to unmap them as a whole. It is not possible to unmap a
   single grant if it has been batch-mapped. A new check has also been added
   to make sure persistent grants are only used if the whole mapped region
   can be persistently mapped in the batch_maps case.
 - Unmap persistent grants before switching to the closed state, so the
   frontend can also free them.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reported-by: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2014-11-14 11:12:38 +00:00

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/*
* xen paravirt block device backend
*
* (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 <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <inttypes.h>
#include <time.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/uio.h>
#include "hw/hw.h"
#include "hw/xen/xen_backend.h"
#include "xen_blkif.h"
#include "sysemu/blockdev.h"
#include "sysemu/block-backend.h"
/* ------------------------------------------------------------- */
static int batch_maps = 0;
static int max_requests = 32;
/* ------------------------------------------------------------- */
#define BLOCK_SIZE 512
#define IOCB_COUNT (BLKIF_MAX_SEGMENTS_PER_REQUEST + 2)
struct PersistentGrant {
void *page;
struct XenBlkDev *blkdev;
};
typedef struct PersistentGrant PersistentGrant;
struct PersistentRegion {
void *addr;
int num;
};
typedef struct PersistentRegion PersistentRegion;
struct ioreq {
blkif_request_t req;
int16_t status;
/* parsed request */
off_t start;
QEMUIOVector v;
int presync;
int postsync;
uint8_t mapped;
/* grant mapping */
uint32_t domids[BLKIF_MAX_SEGMENTS_PER_REQUEST];
uint32_t refs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
int prot;
void *page[BLKIF_MAX_SEGMENTS_PER_REQUEST];
void *pages;
int num_unmap;
/* aio status */
int aio_inflight;
int aio_errors;
struct XenBlkDev *blkdev;
QLIST_ENTRY(ioreq) list;
BlockAcctCookie acct;
};
struct XenBlkDev {
struct XenDevice xendev; /* must be first */
char *params;
char *mode;
char *type;
char *dev;
char *devtype;
bool directiosafe;
const char *fileproto;
const char *filename;
int ring_ref;
void *sring;
int64_t file_blk;
int64_t file_size;
int protocol;
blkif_back_rings_t rings;
int more_work;
int cnt_map;
/* request lists */
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;
/* Persistent grants extension */
gboolean feature_discard;
gboolean feature_persistent;
GTree *persistent_gnts;
GSList *persistent_regions;
unsigned int persistent_gnt_count;
unsigned int max_grants;
/* qemu block driver */
DriveInfo *dinfo;
BlockBackend *blk;
QEMUBH *bh;
};
/* ------------------------------------------------------------- */
static void ioreq_reset(struct ioreq *ioreq)
{
memset(&ioreq->req, 0, sizeof(ioreq->req));
ioreq->status = 0;
ioreq->start = 0;
ioreq->presync = 0;
ioreq->postsync = 0;
ioreq->mapped = 0;
memset(ioreq->domids, 0, sizeof(ioreq->domids));
memset(ioreq->refs, 0, sizeof(ioreq->refs));
ioreq->prot = 0;
memset(ioreq->page, 0, sizeof(ioreq->page));
ioreq->pages = NULL;
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 gint int_cmp(gconstpointer a, gconstpointer b, gpointer user_data)
{
uint ua = GPOINTER_TO_UINT(a);
uint ub = GPOINTER_TO_UINT(b);
return (ua > ub) - (ua < ub);
}
static void destroy_grant(gpointer pgnt)
{
PersistentGrant *grant = pgnt;
XenGnttab gnt = grant->blkdev->xendev.gnttabdev;
if (xc_gnttab_munmap(gnt, grant->page, 1) != 0) {
xen_be_printf(&grant->blkdev->xendev, 0,
"xc_gnttab_munmap failed: %s\n",
strerror(errno));
}
grant->blkdev->persistent_gnt_count--;
xen_be_printf(&grant->blkdev->xendev, 3,
"unmapped grant %p\n", grant->page);
g_free(grant);
}
static void remove_persistent_region(gpointer data, gpointer dev)
{
PersistentRegion *region = data;
struct XenBlkDev *blkdev = dev;
XenGnttab gnt = blkdev->xendev.gnttabdev;
if (xc_gnttab_munmap(gnt, region->addr, region->num) != 0) {
xen_be_printf(&blkdev->xendev, 0,
"xc_gnttab_munmap region %p failed: %s\n",
region->addr, strerror(errno));
}
xen_be_printf(&blkdev->xendev, 3,
"unmapped grant region %p with %d pages\n",
region->addr, region->num);
g_free(region);
}
static struct ioreq *ioreq_start(struct XenBlkDev *blkdev)
{
struct ioreq *ioreq = NULL;
if (QLIST_EMPTY(&blkdev->freelist)) {
if (blkdev->requests_total >= max_requests) {
goto out;
}
/* allocate new struct */
ioreq = g_malloc0(sizeof(*ioreq));
ioreq->blkdev = blkdev;
blkdev->requests_total++;
qemu_iovec_init(&ioreq->v, BLKIF_MAX_SEGMENTS_PER_REQUEST);
} 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;
uintptr_t mem;
size_t len;
int i;
xen_be_printf(&blkdev->xendev, 3,
"op %d, nr %d, handle %d, id %" PRId64 ", sector %" PRId64 "\n",
ioreq->req.operation, ioreq->req.nr_segments,
ioreq->req.handle, ioreq->req.id, ioreq->req.sector_number);
switch (ioreq->req.operation) {
case BLKIF_OP_READ:
ioreq->prot = PROT_WRITE; /* to memory */
break;
case BLKIF_OP_FLUSH_DISKCACHE:
ioreq->presync = 1;
if (!ioreq->req.nr_segments) {
return 0;
}
/* fall through */
case BLKIF_OP_WRITE:
ioreq->prot = PROT_READ; /* from memory */
break;
case BLKIF_OP_DISCARD:
return 0;
default:
xen_be_printf(&blkdev->xendev, 0, "error: unknown operation (%d)\n",
ioreq->req.operation);
goto err;
};
if (ioreq->req.operation != BLKIF_OP_READ && blkdev->mode[0] != 'w') {
xen_be_printf(&blkdev->xendev, 0, "error: write req for ro device\n");
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) {
xen_be_printf(&blkdev->xendev, 0, "error: nr_segments too big\n");
goto err;
}
if (ioreq->req.seg[i].first_sect > ioreq->req.seg[i].last_sect) {
xen_be_printf(&blkdev->xendev, 0, "error: first > last sector\n");
goto err;
}
if (ioreq->req.seg[i].last_sect * BLOCK_SIZE >= XC_PAGE_SIZE) {
xen_be_printf(&blkdev->xendev, 0, "error: page crossing\n");
goto err;
}
ioreq->domids[i] = blkdev->xendev.dom;
ioreq->refs[i] = ioreq->req.seg[i].gref;
mem = ioreq->req.seg[i].first_sect * blkdev->file_blk;
len = (ioreq->req.seg[i].last_sect - ioreq->req.seg[i].first_sect + 1) * blkdev->file_blk;
qemu_iovec_add(&ioreq->v, (void*)mem, len);
}
if (ioreq->start + ioreq->v.size > blkdev->file_size) {
xen_be_printf(&blkdev->xendev, 0, "error: access beyond end of file\n");
goto err;
}
return 0;
err:
ioreq->status = BLKIF_RSP_ERROR;
return -1;
}
static void ioreq_unmap(struct ioreq *ioreq)
{
XenGnttab gnt = ioreq->blkdev->xendev.gnttabdev;
int i;
if (ioreq->num_unmap == 0 || ioreq->mapped == 0) {
return;
}
if (batch_maps) {
if (!ioreq->pages) {
return;
}
if (xc_gnttab_munmap(gnt, ioreq->pages, ioreq->num_unmap) != 0) {
xen_be_printf(&ioreq->blkdev->xendev, 0, "xc_gnttab_munmap failed: %s\n",
strerror(errno));
}
ioreq->blkdev->cnt_map -= ioreq->num_unmap;
ioreq->pages = NULL;
} else {
for (i = 0; i < ioreq->num_unmap; i++) {
if (!ioreq->page[i]) {
continue;
}
if (xc_gnttab_munmap(gnt, ioreq->page[i], 1) != 0) {
xen_be_printf(&ioreq->blkdev->xendev, 0, "xc_gnttab_munmap failed: %s\n",
strerror(errno));
}
ioreq->blkdev->cnt_map--;
ioreq->page[i] = NULL;
}
}
ioreq->mapped = 0;
}
static int ioreq_map(struct ioreq *ioreq)
{
XenGnttab gnt = ioreq->blkdev->xendev.gnttabdev;
uint32_t domids[BLKIF_MAX_SEGMENTS_PER_REQUEST];
uint32_t refs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
void *page[BLKIF_MAX_SEGMENTS_PER_REQUEST];
int i, j, new_maps = 0;
PersistentGrant *grant;
PersistentRegion *region;
/* domids and refs variables will contain the information necessary
* to map the grants that are needed to fulfill this request.
*
* After mapping the needed grants, the page array will contain the
* memory address of each granted page in the order specified in ioreq
* (disregarding if it's a persistent grant or not).
*/
if (ioreq->v.niov == 0 || ioreq->mapped == 1) {
return 0;
}
if (ioreq->blkdev->feature_persistent) {
for (i = 0; i < ioreq->v.niov; i++) {
grant = g_tree_lookup(ioreq->blkdev->persistent_gnts,
GUINT_TO_POINTER(ioreq->refs[i]));
if (grant != NULL) {
page[i] = grant->page;
xen_be_printf(&ioreq->blkdev->xendev, 3,
"using persistent-grant %" PRIu32 "\n",
ioreq->refs[i]);
} else {
/* Add the grant to the list of grants that
* should be mapped
*/
domids[new_maps] = ioreq->domids[i];
refs[new_maps] = ioreq->refs[i];
page[i] = NULL;
new_maps++;
}
}
/* Set the protection to RW, since grants may be reused later
* with a different protection than the one needed for this request
*/
ioreq->prot = PROT_WRITE | PROT_READ;
} else {
/* All grants in the request should be mapped */
memcpy(refs, ioreq->refs, sizeof(refs));
memcpy(domids, ioreq->domids, sizeof(domids));
memset(page, 0, sizeof(page));
new_maps = ioreq->v.niov;
}
if (batch_maps && new_maps) {
ioreq->pages = xc_gnttab_map_grant_refs
(gnt, new_maps, domids, refs, ioreq->prot);
if (ioreq->pages == NULL) {
xen_be_printf(&ioreq->blkdev->xendev, 0,
"can't map %d grant refs (%s, %d maps)\n",
new_maps, strerror(errno), ioreq->blkdev->cnt_map);
return -1;
}
for (i = 0, j = 0; i < ioreq->v.niov; i++) {
if (page[i] == NULL) {
page[i] = ioreq->pages + (j++) * XC_PAGE_SIZE;
}
}
ioreq->blkdev->cnt_map += new_maps;
} else if (new_maps) {
for (i = 0; i < new_maps; i++) {
ioreq->page[i] = xc_gnttab_map_grant_ref
(gnt, domids[i], refs[i], ioreq->prot);
if (ioreq->page[i] == NULL) {
xen_be_printf(&ioreq->blkdev->xendev, 0,
"can't map grant ref %d (%s, %d maps)\n",
refs[i], strerror(errno), ioreq->blkdev->cnt_map);
ioreq->mapped = 1;
ioreq_unmap(ioreq);
return -1;
}
ioreq->blkdev->cnt_map++;
}
for (i = 0, j = 0; i < ioreq->v.niov; i++) {
if (page[i] == NULL) {
page[i] = ioreq->page[j++];
}
}
}
if (ioreq->blkdev->feature_persistent && new_maps != 0 &&
(!batch_maps || (ioreq->blkdev->persistent_gnt_count + new_maps <=
ioreq->blkdev->max_grants))) {
/*
* If we are using persistent grants and batch mappings only
* add the new maps to the list of persistent grants if the whole
* area can be persistently mapped.
*/
if (batch_maps) {
region = g_malloc0(sizeof(*region));
region->addr = ioreq->pages;
region->num = new_maps;
ioreq->blkdev->persistent_regions = g_slist_append(
ioreq->blkdev->persistent_regions,
region);
}
while ((ioreq->blkdev->persistent_gnt_count < ioreq->blkdev->max_grants)
&& new_maps) {
/* Go through the list of newly mapped grants and add as many
* as possible to the list of persistently mapped grants.
*
* Since we start at the end of ioreq->page(s), we only need
* to decrease new_maps to prevent this granted pages from
* being unmapped in ioreq_unmap.
*/
grant = g_malloc0(sizeof(*grant));
new_maps--;
if (batch_maps) {
grant->page = ioreq->pages + (new_maps) * XC_PAGE_SIZE;
} else {
grant->page = ioreq->page[new_maps];
}
grant->blkdev = ioreq->blkdev;
xen_be_printf(&ioreq->blkdev->xendev, 3,
"adding grant %" PRIu32 " page: %p\n",
refs[new_maps], grant->page);
g_tree_insert(ioreq->blkdev->persistent_gnts,
GUINT_TO_POINTER(refs[new_maps]),
grant);
ioreq->blkdev->persistent_gnt_count++;
}
assert(!batch_maps || new_maps == 0);
}
for (i = 0; i < ioreq->v.niov; i++) {
ioreq->v.iov[i].iov_base += (uintptr_t)page[i];
}
ioreq->mapped = 1;
ioreq->num_unmap = new_maps;
return 0;
}
static int ioreq_runio_qemu_aio(struct ioreq *ioreq);
static void qemu_aio_complete(void *opaque, int ret)
{
struct ioreq *ioreq = opaque;
if (ret != 0) {
xen_be_printf(&ioreq->blkdev->xendev, 0, "%s I/O error\n",
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);
return;
}
if (ioreq->aio_inflight > 0) {
return;
}
if (ioreq->postsync) {
ioreq->postsync = 0;
ioreq->aio_inflight++;
blk_aio_flush(ioreq->blkdev->blk, qemu_aio_complete, ioreq);
return;
}
ioreq->status = ioreq->aio_errors ? BLKIF_RSP_ERROR : BLKIF_RSP_OKAY;
ioreq_unmap(ioreq);
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:
block_acct_done(blk_get_stats(ioreq->blkdev->blk), &ioreq->acct);
break;
case BLKIF_OP_DISCARD:
default:
break;
}
qemu_bh_schedule(ioreq->blkdev->bh);
}
static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
if (ioreq->req.nr_segments && ioreq_map(ioreq) == -1) {
goto err_no_map;
}
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:
block_acct_start(blk_get_stats(blkdev->blk), &ioreq->acct,
ioreq->v.size, BLOCK_ACCT_READ);
ioreq->aio_inflight++;
blk_aio_readv(blkdev->blk, ioreq->start / BLOCK_SIZE,
&ioreq->v, ioreq->v.size / BLOCK_SIZE,
qemu_aio_complete, ioreq);
break;
case BLKIF_OP_WRITE:
case BLKIF_OP_FLUSH_DISKCACHE:
if (!ioreq->req.nr_segments) {
break;
}
block_acct_start(blk_get_stats(blkdev->blk), &ioreq->acct,
ioreq->v.size, BLOCK_ACCT_WRITE);
ioreq->aio_inflight++;
blk_aio_writev(blkdev->blk, ioreq->start / BLOCK_SIZE,
&ioreq->v, ioreq->v.size / BLOCK_SIZE,
qemu_aio_complete, ioreq);
break;
case BLKIF_OP_DISCARD:
{
struct blkif_request_discard *discard_req = (void *)&ioreq->req;
ioreq->aio_inflight++;
blk_aio_discard(blkdev->blk,
discard_req->sector_number, discard_req->nr_sectors,
qemu_aio_complete, ioreq);
break;
}
default:
/* unknown operation (shouldn't happen -- parse catches this) */
goto err;
}
qemu_aio_complete(ioreq, 0);
return 0;
err:
ioreq_unmap(ioreq);
err_no_map:
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;
void *dst;
resp.id = ioreq->req.id;
resp.operation = ioreq->req.operation;
resp.status = ioreq->status;
/* Place on the response ring for the relevant domain. */
switch (blkdev->protocol) {
case BLKIF_PROTOCOL_NATIVE:
dst = RING_GET_RESPONSE(&blkdev->rings.native, blkdev->rings.native.rsp_prod_pvt);
break;
case BLKIF_PROTOCOL_X86_32:
dst = RING_GET_RESPONSE(&blkdev->rings.x86_32_part,
blkdev->rings.x86_32_part.rsp_prod_pvt);
break;
case BLKIF_PROTOCOL_X86_64:
dst = RING_GET_RESPONSE(&blkdev->rings.x86_64_part,
blkdev->rings.x86_64_part.rsp_prod_pvt);
break;
default:
dst = NULL;
return 0;
}
memcpy(dst, &resp, sizeof(resp));
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) {
xen_be_send_notify(&blkdev->xendev);
}
}
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;
}
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) {
if (blk_send_response_one(ioreq)) {
xen_be_send_notify(&blkdev->xendev);
}
ioreq_release(ioreq, false);
continue;
}
ioreq_runio_qemu_aio(ioreq);
}
if (blkdev->more_work && blkdev->requests_inflight < max_requests) {
qemu_bh_schedule(blkdev->bh);
}
}
/* ------------------------------------------------------------- */
static void blk_bh(void *opaque)
{
struct XenBlkDev *blkdev = opaque;
blk_handle_requests(blkdev);
}
/*
* We need to account for the grant allocations requiring contiguous
* chunks; the worst case number would be
* max_req * max_seg + (max_req - 1) * (max_seg - 1) + 1,
* but in order to keep things simple just use
* 2 * max_req * max_seg.
*/
#define MAX_GRANTS(max_req, max_seg) (2 * (max_req) * (max_seg))
static void blk_alloc(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
QLIST_INIT(&blkdev->inflight);
QLIST_INIT(&blkdev->finished);
QLIST_INIT(&blkdev->freelist);
blkdev->bh = qemu_bh_new(blk_bh, blkdev);
if (xen_mode != XEN_EMULATE) {
batch_maps = 1;
}
if (xc_gnttab_set_max_grants(xendev->gnttabdev,
MAX_GRANTS(max_requests, BLKIF_MAX_SEGMENTS_PER_REQUEST)) < 0) {
xen_be_printf(xendev, 0, "xc_gnttab_set_max_grants failed: %s\n",
strerror(errno));
}
}
static void blk_parse_discard(struct XenBlkDev *blkdev)
{
int enable;
blkdev->feature_discard = true;
if (xenstore_read_be_int(&blkdev->xendev, "discard-enable", &enable) == 0) {
blkdev->feature_discard = !!enable;
}
if (blkdev->feature_discard) {
xenstore_write_be_int(&blkdev->xendev, "feature-discard", 1);
}
}
static int blk_init(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
int info = 0;
char *directiosafe = NULL;
/* read xenstore entries */
if (blkdev->params == NULL) {
char *h = NULL;
blkdev->params = xenstore_read_be_str(&blkdev->xendev, "params");
if (blkdev->params != NULL) {
h = strchr(blkdev->params, ':');
}
if (h != NULL) {
blkdev->fileproto = blkdev->params;
blkdev->filename = h+1;
*h = 0;
} else {
blkdev->fileproto = "<unset>";
blkdev->filename = blkdev->params;
}
}
if (!strcmp("aio", blkdev->fileproto)) {
blkdev->fileproto = "raw";
}
if (blkdev->mode == NULL) {
blkdev->mode = xenstore_read_be_str(&blkdev->xendev, "mode");
}
if (blkdev->type == NULL) {
blkdev->type = xenstore_read_be_str(&blkdev->xendev, "type");
}
if (blkdev->dev == NULL) {
blkdev->dev = xenstore_read_be_str(&blkdev->xendev, "dev");
}
if (blkdev->devtype == NULL) {
blkdev->devtype = xenstore_read_be_str(&blkdev->xendev, "device-type");
}
directiosafe = xenstore_read_be_str(&blkdev->xendev, "direct-io-safe");
blkdev->directiosafe = (directiosafe && atoi(directiosafe));
/* do we have all we need? */
if (blkdev->params == NULL ||
blkdev->mode == NULL ||
blkdev->type == NULL ||
blkdev->dev == NULL) {
goto out_error;
}
/* read-only ? */
if (strcmp(blkdev->mode, "w")) {
info |= VDISK_READONLY;
}
/* cdrom ? */
if (blkdev->devtype && !strcmp(blkdev->devtype, "cdrom")) {
info |= VDISK_CDROM;
}
blkdev->file_blk = BLOCK_SIZE;
/* fill info
* blk_connect supplies sector-size and sectors
*/
xenstore_write_be_int(&blkdev->xendev, "feature-flush-cache", 1);
xenstore_write_be_int(&blkdev->xendev, "feature-persistent", 1);
xenstore_write_be_int(&blkdev->xendev, "info", info);
blk_parse_discard(blkdev);
g_free(directiosafe);
return 0;
out_error:
g_free(blkdev->params);
blkdev->params = NULL;
g_free(blkdev->mode);
blkdev->mode = NULL;
g_free(blkdev->type);
blkdev->type = NULL;
g_free(blkdev->dev);
blkdev->dev = NULL;
g_free(blkdev->devtype);
blkdev->devtype = NULL;
g_free(directiosafe);
blkdev->directiosafe = false;
return -1;
}
static int blk_connect(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
int pers, index, qflags;
bool readonly = true;
/* read-only ? */
if (blkdev->directiosafe) {
qflags = BDRV_O_NOCACHE | BDRV_O_NATIVE_AIO;
} else {
qflags = BDRV_O_CACHE_WB;
}
if (strcmp(blkdev->mode, "w") == 0) {
qflags |= BDRV_O_RDWR;
readonly = false;
}
if (blkdev->feature_discard) {
qflags |= BDRV_O_UNMAP;
}
/* init qemu block driver */
index = (blkdev->xendev.dev - 202 * 256) / 16;
blkdev->dinfo = drive_get(IF_XEN, 0, index);
if (!blkdev->dinfo) {
Error *local_err = NULL;
BlockBackend *blk;
BlockDriver *drv;
BlockDriverState *bs;
/* setup via xenbus -> create new block driver instance */
xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
blk = blk_new_with_bs(blkdev->dev, NULL);
if (!blk) {
return -1;
}
blkdev->blk = blk;
bs = blk_bs(blk);
drv = bdrv_find_whitelisted_format(blkdev->fileproto, readonly);
if (bdrv_open(&bs, blkdev->filename, NULL, NULL, qflags,
drv, &local_err) != 0) {
xen_be_printf(&blkdev->xendev, 0, "error: %s\n",
error_get_pretty(local_err));
error_free(local_err);
blk_unref(blk);
blkdev->blk = NULL;
return -1;
}
assert(bs == blk_bs(blk));
} else {
/* setup via qemu cmdline -> already setup for us */
xen_be_printf(&blkdev->xendev, 2, "get configured bdrv (cmdline setup)\n");
blkdev->blk = blk_by_legacy_dinfo(blkdev->dinfo);
if (blk_is_read_only(blkdev->blk) && !readonly) {
xen_be_printf(&blkdev->xendev, 0, "Unexpected read-only drive");
blkdev->blk = NULL;
return -1;
}
/* blkdev->blk is not create by us, we get a reference
* so we can blk_unref() unconditionally */
blk_ref(blkdev->blk);
}
blk_attach_dev_nofail(blkdev->blk, blkdev);
blkdev->file_size = blk_getlength(blkdev->blk);
if (blkdev->file_size < 0) {
xen_be_printf(&blkdev->xendev, 1, "blk_getlength: %d (%s) | drv %s\n",
(int)blkdev->file_size, strerror(-blkdev->file_size),
bdrv_get_format_name(blk_bs(blkdev->blk)) ?: "-");
blkdev->file_size = 0;
}
xen_be_printf(xendev, 1, "type \"%s\", fileproto \"%s\", filename \"%s\","
" size %" PRId64 " (%" PRId64 " MB)\n",
blkdev->type, blkdev->fileproto, blkdev->filename,
blkdev->file_size, blkdev->file_size >> 20);
/* Fill in number of sector size and number of sectors */
xenstore_write_be_int(&blkdev->xendev, "sector-size", blkdev->file_blk);
xenstore_write_be_int64(&blkdev->xendev, "sectors",
blkdev->file_size / blkdev->file_blk);
if (xenstore_read_fe_int(&blkdev->xendev, "ring-ref", &blkdev->ring_ref) == -1) {
return -1;
}
if (xenstore_read_fe_int(&blkdev->xendev, "event-channel",
&blkdev->xendev.remote_port) == -1) {
return -1;
}
if (xenstore_read_fe_int(&blkdev->xendev, "feature-persistent", &pers)) {
blkdev->feature_persistent = FALSE;
} else {
blkdev->feature_persistent = !!pers;
}
blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
if (blkdev->xendev.protocol) {
if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_32) == 0) {
blkdev->protocol = BLKIF_PROTOCOL_X86_32;
}
if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_64) == 0) {
blkdev->protocol = BLKIF_PROTOCOL_X86_64;
}
}
blkdev->sring = xc_gnttab_map_grant_ref(blkdev->xendev.gnttabdev,
blkdev->xendev.dom,
blkdev->ring_ref,
PROT_READ | PROT_WRITE);
if (!blkdev->sring) {
return -1;
}
blkdev->cnt_map++;
switch (blkdev->protocol) {
case BLKIF_PROTOCOL_NATIVE:
{
blkif_sring_t *sring_native = blkdev->sring;
BACK_RING_INIT(&blkdev->rings.native, sring_native, XC_PAGE_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, XC_PAGE_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, XC_PAGE_SIZE);
break;
}
}
if (blkdev->feature_persistent) {
/* Init persistent grants */
blkdev->max_grants = max_requests * BLKIF_MAX_SEGMENTS_PER_REQUEST;
blkdev->persistent_gnts = g_tree_new_full((GCompareDataFunc)int_cmp,
NULL, NULL,
batch_maps ?
(GDestroyNotify)g_free :
(GDestroyNotify)destroy_grant);
blkdev->persistent_regions = NULL;
blkdev->persistent_gnt_count = 0;
}
xen_be_bind_evtchn(&blkdev->xendev);
xen_be_printf(&blkdev->xendev, 1, "ok: proto %s, ring-ref %d, "
"remote port %d, local port %d\n",
blkdev->xendev.protocol, blkdev->ring_ref,
blkdev->xendev.remote_port, blkdev->xendev.local_port);
return 0;
}
static void blk_disconnect(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
if (blkdev->blk) {
blk_detach_dev(blkdev->blk, blkdev);
blk_unref(blkdev->blk);
blkdev->blk = NULL;
}
xen_be_unbind_evtchn(&blkdev->xendev);
if (blkdev->sring) {
xc_gnttab_munmap(blkdev->xendev.gnttabdev, blkdev->sring, 1);
blkdev->cnt_map--;
blkdev->sring = NULL;
}
/*
* Unmap persistent grants before switching to the closed state
* so the frontend can free them.
*
* In the !batch_maps case g_tree_destroy will take care of unmapping
* the grant, but in the batch_maps case we need to iterate over every
* region in persistent_regions and unmap it.
*/
if (blkdev->feature_persistent) {
g_tree_destroy(blkdev->persistent_gnts);
assert(batch_maps || blkdev->persistent_gnt_count == 0);
if (batch_maps) {
blkdev->persistent_gnt_count = 0;
g_slist_foreach(blkdev->persistent_regions,
(GFunc)remove_persistent_region, blkdev);
g_slist_free(blkdev->persistent_regions);
}
blkdev->feature_persistent = false;
}
}
static int blk_free(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
struct ioreq *ioreq;
if (blkdev->blk || blkdev->sring) {
blk_disconnect(xendev);
}
while (!QLIST_EMPTY(&blkdev->freelist)) {
ioreq = QLIST_FIRST(&blkdev->freelist);
QLIST_REMOVE(ioreq, list);
qemu_iovec_destroy(&ioreq->v);
g_free(ioreq);
}
g_free(blkdev->params);
g_free(blkdev->mode);
g_free(blkdev->type);
g_free(blkdev->dev);
g_free(blkdev->devtype);
qemu_bh_delete(blkdev->bh);
return 0;
}
static void blk_event(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
qemu_bh_schedule(blkdev->bh);
}
struct XenDevOps xen_blkdev_ops = {
.size = sizeof(struct XenBlkDev),
.flags = DEVOPS_FLAG_NEED_GNTDEV,
.alloc = blk_alloc,
.init = blk_init,
.initialise = blk_connect,
.disconnect = blk_disconnect,
.event = blk_event,
.free = blk_free,
};
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