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xemu/hw/block/xen_disk.c
Ian Campbell c1345a8878 xen: Switch to libxengnttab interface for compat shims. 
In Xen 4.7 we are refactoring parts libxenctrl into a number of
separate libraries which will provide backward and forward API and ABI
compatiblity.

One such library will be libxengnttab which provides access to grant
tables.

In preparation for this switch the compatibility layer in xen_common.h
(which support building with older versions of Xen) to use what will
be the new library API. This means that the gnttab shim will disappear
for versions of Xen which include libxengnttab.

To simplify things for the <= 4.0.0 support we wrap the int fd in a
malloc(sizeof int) such that the handle is always a pointer. This
leads to less typedef headaches and the need for
XC_HANDLER_INITIAL_VALUE etc for these interfaces.

Note that this patch does not add any support for actually using
libxengnttab, it just adjusts the existing shims.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
2016-01-26 17:19:28 +00:00

1118 lines
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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 "qemu/osdep.h"
#include <sys/ioctl.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"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qstring.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;
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->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_handle *gnt = grant->blkdev->xendev.gnttabdev;
if (xengnttab_unmap(gnt, grant->page, 1) != 0) {
xen_be_printf(&grant->blkdev->xendev, 0,
"xengnttab_unmap 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_handle *gnt = blkdev->xendev.gnttabdev;
if (xengnttab_unmap(gnt, region->addr, region->num) != 0) {
xen_be_printf(&blkdev->xendev, 0,
"xengnttab_unmap 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_handle *gnt = ioreq->blkdev->xendev.gnttabdev;
int i;
if (ioreq->num_unmap == 0 || ioreq->mapped == 0) {
return;
}
if (batch_maps) {
if (!ioreq->pages) {
return;
}
if (xengnttab_unmap(gnt, ioreq->pages, ioreq->num_unmap) != 0) {
xen_be_printf(&ioreq->blkdev->xendev, 0,
"xengnttab_unmap 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 (xengnttab_unmap(gnt, ioreq->page[i], 1) != 0) {
xen_be_printf(&ioreq->blkdev->xendev, 0,
"xengnttab_unmap failed: %s\n",
strerror(errno));
}
ioreq->blkdev->cnt_map--;
ioreq->page[i] = NULL;
}
}
ioreq->mapped = 0;
}
static int ioreq_map(struct ioreq *ioreq)
{
xengnttab_handle *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 = xengnttab_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] = xengnttab_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;
}
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:
if (ioreq->status == BLKIF_RSP_OKAY) {
block_acct_done(blk_get_stats(ioreq->blkdev->blk), &ioreq->acct);
} else {
block_acct_failed(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,
ioreq->req.operation == BLKIF_OP_WRITE ?
BLOCK_ACCT_WRITE : BLOCK_ACCT_FLUSH);
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) {
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)) {
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 (xengnttab_set_max_grants(xendev->gnttabdev,
MAX_GRANTS(max_requests, BLKIF_MAX_SEGMENTS_PER_REQUEST)) < 0) {
xen_be_printf(xendev, 0, "xengnttab_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 (!strcmp("vhd", blkdev->fileproto)) {
blkdev->fileproto = "vpc";
}
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;
QDict *options = NULL;
if (strcmp(blkdev->fileproto, "<unset>")) {
options = qdict_new();
qdict_put(options, "driver", qstring_from_str(blkdev->fileproto));
}
/* setup via xenbus -> create new block driver instance */
xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
blkdev->blk = blk_new_open(blkdev->dev, blkdev->filename, NULL, options,
qflags, &local_err);
if (!blkdev->blk) {
xen_be_printf(&blkdev->xendev, 0, "error: %s\n",
error_get_pretty(local_err));
error_free(local_err);
return -1;
}
} 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) {
BlockDriverState *bs = blk_bs(blkdev->blk);
const char *drv_name = bs ? bdrv_get_format_name(bs) : NULL;
xen_be_printf(&blkdev->xendev, 1, "blk_getlength: %d (%s) | drv %s\n",
(int)blkdev->file_size, strerror(-blkdev->file_size),
drv_name ?: "-");
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 = xengnttab_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) {
xengnttab_unmap(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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