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qemu/hw/xen_backend.c

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/*
* xen backend driver infrastructure
* (c) 2008 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.
*/
/*
* TODO: add some xenbus / xenstore concepts overview here.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <inttypes.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/signal.h>
#include "hw.h"
#include "qemu-char.h"
#include "qemu-log.h"
#include "xen_backend.h"
#include <xen/grant_table.h>
/* ------------------------------------------------------------- */
/* public */
XenXC xen_xc = XC_HANDLER_INITIAL_VALUE;
XenGnttab xen_xcg = XC_HANDLER_INITIAL_VALUE;
struct xs_handle *xenstore = NULL;
const char *xen_protocol;
/* private */
static QTAILQ_HEAD(XenDeviceHead, XenDevice) xendevs = QTAILQ_HEAD_INITIALIZER(xendevs);
static int debug = 0;
/* ------------------------------------------------------------- */
int xenstore_write_str(const char *base, const char *node, const char *val)
{
char abspath[XEN_BUFSIZE];
snprintf(abspath, sizeof(abspath), "%s/%s", base, node);
if (!xs_write(xenstore, 0, abspath, val, strlen(val))) {
return -1;
}
return 0;
}
char *xenstore_read_str(const char *base, const char *node)
{
char abspath[XEN_BUFSIZE];
unsigned int len;
char *str, *ret = NULL;
snprintf(abspath, sizeof(abspath), "%s/%s", base, node);
str = xs_read(xenstore, 0, abspath, &len);
if (str != NULL) {
/* move to qemu-allocated memory to make sure
* callers can savely g_free() stuff. */
ret = g_strdup(str);
free(str);
}
return ret;
}
int xenstore_write_int(const char *base, const char *node, int ival)
{
char val[32];
snprintf(val, sizeof(val), "%d", ival);
return xenstore_write_str(base, node, val);
}
int xenstore_read_int(const char *base, const char *node, int *ival)
{
char *val;
int rc = -1;
val = xenstore_read_str(base, node);
if (val && 1 == sscanf(val, "%d", ival)) {
rc = 0;
}
g_free(val);
return rc;
}
int xenstore_write_be_str(struct XenDevice *xendev, const char *node, const char *val)
{
return xenstore_write_str(xendev->be, node, val);
}
int xenstore_write_be_int(struct XenDevice *xendev, const char *node, int ival)
{
return xenstore_write_int(xendev->be, node, ival);
}
char *xenstore_read_be_str(struct XenDevice *xendev, const char *node)
{
return xenstore_read_str(xendev->be, node);
}
int xenstore_read_be_int(struct XenDevice *xendev, const char *node, int *ival)
{
return xenstore_read_int(xendev->be, node, ival);
}
char *xenstore_read_fe_str(struct XenDevice *xendev, const char *node)
{
return xenstore_read_str(xendev->fe, node);
}
int xenstore_read_fe_int(struct XenDevice *xendev, const char *node, int *ival)
{
return xenstore_read_int(xendev->fe, node, ival);
}
/* ------------------------------------------------------------- */
const char *xenbus_strstate(enum xenbus_state state)
{
static const char *const name[] = {
[ XenbusStateUnknown ] = "Unknown",
[ XenbusStateInitialising ] = "Initialising",
[ XenbusStateInitWait ] = "InitWait",
[ XenbusStateInitialised ] = "Initialised",
[ XenbusStateConnected ] = "Connected",
[ XenbusStateClosing ] = "Closing",
[ XenbusStateClosed ] = "Closed",
};
return (state < ARRAY_SIZE(name)) ? name[state] : "INVALID";
}
int xen_be_set_state(struct XenDevice *xendev, enum xenbus_state state)
{
int rc;
rc = xenstore_write_be_int(xendev, "state", state);
if (rc < 0) {
return rc;
}
xen_be_printf(xendev, 1, "backend state: %s -> %s\n",
xenbus_strstate(xendev->be_state), xenbus_strstate(state));
xendev->be_state = state;
return 0;
}
/* ------------------------------------------------------------- */
struct XenDevice *xen_be_find_xendev(const char *type, int dom, int dev)
{
struct XenDevice *xendev;
QTAILQ_FOREACH(xendev, &xendevs, next) {
if (xendev->dom != dom) {
continue;
}
if (xendev->dev != dev) {
continue;
}
if (strcmp(xendev->type, type) != 0) {
continue;
}
return xendev;
}
return NULL;
}
/*
* get xen backend device, allocate a new one if it doesn't exist.
*/
static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
struct XenDevOps *ops)
{
struct XenDevice *xendev;
char *dom0;
xendev = xen_be_find_xendev(type, dom, dev);
if (xendev) {
return xendev;
}
/* init new xendev */
xendev = g_malloc0(ops->size);
xendev->type = type;
xendev->dom = dom;
xendev->dev = dev;
xendev->ops = ops;
dom0 = xs_get_domain_path(xenstore, 0);
snprintf(xendev->be, sizeof(xendev->be), "%s/backend/%s/%d/%d",
dom0, xendev->type, xendev->dom, xendev->dev);
snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
xendev->type, xendev->dev);
free(dom0);
xendev->debug = debug;
xendev->local_port = -1;
xendev->evtchndev = xen_xc_evtchn_open(NULL, 0);
if (xendev->evtchndev == XC_HANDLER_INITIAL_VALUE) {
xen_be_printf(NULL, 0, "can't open evtchn device\n");
g_free(xendev);
return NULL;
}
fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
xendev->gnttabdev = xen_xc_gnttab_open(NULL, 0);
if (xendev->gnttabdev == XC_HANDLER_INITIAL_VALUE) {
xen_be_printf(NULL, 0, "can't open gnttab device\n");
xc_evtchn_close(xendev->evtchndev);
g_free(xendev);
return NULL;
}
} else {
xendev->gnttabdev = XC_HANDLER_INITIAL_VALUE;
}
QTAILQ_INSERT_TAIL(&xendevs, xendev, next);
if (xendev->ops->alloc) {
xendev->ops->alloc(xendev);
}
return xendev;
}
/*
* release xen backend device.
*/
static struct XenDevice *xen_be_del_xendev(int dom, int dev)
{
struct XenDevice *xendev, *xnext;
/*
* This is pretty much like QTAILQ_FOREACH(xendev, &xendevs, next) but
* we save the next pointer in xnext because we might free xendev.
*/
xnext = xendevs.tqh_first;
while (xnext) {
xendev = xnext;
xnext = xendev->next.tqe_next;
if (xendev->dom != dom) {
continue;
}
if (xendev->dev != dev && dev != -1) {
continue;
}
if (xendev->ops->free) {
xendev->ops->free(xendev);
}
if (xendev->fe) {
char token[XEN_BUFSIZE];
snprintf(token, sizeof(token), "fe:%p", xendev);
xs_unwatch(xenstore, xendev->fe, token);
g_free(xendev->fe);
}
if (xendev->evtchndev != XC_HANDLER_INITIAL_VALUE) {
xc_evtchn_close(xendev->evtchndev);
}
if (xendev->gnttabdev != XC_HANDLER_INITIAL_VALUE) {
xc_gnttab_close(xendev->gnttabdev);
}
QTAILQ_REMOVE(&xendevs, xendev, next);
g_free(xendev);
}
return NULL;
}
/*
* Sync internal data structures on xenstore updates.
* Node specifies the changed field. node = NULL means
* update all fields (used for initialization).
*/
static void xen_be_backend_changed(struct XenDevice *xendev, const char *node)
{
if (node == NULL || strcmp(node, "online") == 0) {
if (xenstore_read_be_int(xendev, "online", &xendev->online) == -1) {
xendev->online = 0;
}
}
if (node) {
xen_be_printf(xendev, 2, "backend update: %s\n", node);
if (xendev->ops->backend_changed) {
xendev->ops->backend_changed(xendev, node);
}
}
}
static void xen_be_frontend_changed(struct XenDevice *xendev, const char *node)
{
int fe_state;
if (node == NULL || strcmp(node, "state") == 0) {
if (xenstore_read_fe_int(xendev, "state", &fe_state) == -1) {
fe_state = XenbusStateUnknown;
}
if (xendev->fe_state != fe_state) {
xen_be_printf(xendev, 1, "frontend state: %s -> %s\n",
xenbus_strstate(xendev->fe_state),
xenbus_strstate(fe_state));
}
xendev->fe_state = fe_state;
}
if (node == NULL || strcmp(node, "protocol") == 0) {
g_free(xendev->protocol);
xendev->protocol = xenstore_read_fe_str(xendev, "protocol");
if (xendev->protocol) {
xen_be_printf(xendev, 1, "frontend protocol: %s\n", xendev->protocol);
}
}
if (node) {
xen_be_printf(xendev, 2, "frontend update: %s\n", node);
if (xendev->ops->frontend_changed) {
xendev->ops->frontend_changed(xendev, node);
}
}
}
/* ------------------------------------------------------------- */
/* Check for possible state transitions and perform them. */
/*
* Initial xendev setup. Read frontend path, register watch for it.
* Should succeed once xend finished setting up the backend device.
*
* Also sets initial state (-> Initializing) when done. Which
* only affects the xendev->be_state variable as xenbus should
* already be put into that state by xend.
*/
static int xen_be_try_setup(struct XenDevice *xendev)
{
char token[XEN_BUFSIZE];
int be_state;
if (xenstore_read_be_int(xendev, "state", &be_state) == -1) {
xen_be_printf(xendev, 0, "reading backend state failed\n");
return -1;
}
if (be_state != XenbusStateInitialising) {
xen_be_printf(xendev, 0, "initial backend state is wrong (%s)\n",
xenbus_strstate(be_state));
return -1;
}
xendev->fe = xenstore_read_be_str(xendev, "frontend");
if (xendev->fe == NULL) {
xen_be_printf(xendev, 0, "reading frontend path failed\n");
return -1;
}
/* setup frontend watch */
snprintf(token, sizeof(token), "fe:%p", xendev);
if (!xs_watch(xenstore, xendev->fe, token)) {
xen_be_printf(xendev, 0, "watching frontend path (%s) failed\n",
xendev->fe);
return -1;
}
xen_be_set_state(xendev, XenbusStateInitialising);
xen_be_backend_changed(xendev, NULL);
xen_be_frontend_changed(xendev, NULL);
return 0;
}
/*
* Try initialize xendev. Prepare everything the backend can do
* without synchronizing with the frontend. Fakes hotplug-status. No
* hotplug involved here because this is about userspace drivers, thus
* there are kernel backend devices which could invoke hotplug.
*
* Goes to InitWait on success.
*/
static int xen_be_try_init(struct XenDevice *xendev)
{
int rc = 0;
if (!xendev->online) {
xen_be_printf(xendev, 1, "not online\n");
return -1;
}
if (xendev->ops->init) {
rc = xendev->ops->init(xendev);
}
if (rc != 0) {
xen_be_printf(xendev, 1, "init() failed\n");
return rc;
}
xenstore_write_be_str(xendev, "hotplug-status", "connected");
xen_be_set_state(xendev, XenbusStateInitWait);
return 0;
}
/*
* Try to initialise xendev. Depends on the frontend being ready
* for it (shared ring and evtchn info in xenstore, state being
* Initialised or Connected).
*
* Goes to Connected on success.
*/
static int xen_be_try_initialise(struct XenDevice *xendev)
{
int rc = 0;
if (xendev->fe_state != XenbusStateInitialised &&
xendev->fe_state != XenbusStateConnected) {
if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
xen_be_printf(xendev, 2, "frontend not ready, ignoring\n");
} else {
xen_be_printf(xendev, 2, "frontend not ready (yet)\n");
return -1;
}
}
if (xendev->ops->initialise) {
rc = xendev->ops->initialise(xendev);
}
if (rc != 0) {
xen_be_printf(xendev, 0, "initialise() failed\n");
return rc;
}
xen_be_set_state(xendev, XenbusStateConnected);
return 0;
}
/*
* Try to let xendev know that it is connected. Depends on the
* frontend being Connected. Note that this may be called more
* than once since the backend state is not modified.
*/
static void xen_be_try_connected(struct XenDevice *xendev)
{
if (!xendev->ops->connected) {
return;
}
if (xendev->fe_state != XenbusStateConnected) {
if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
xen_be_printf(xendev, 2, "frontend not ready, ignoring\n");
} else {
xen_be_printf(xendev, 2, "frontend not ready (yet)\n");
return;
}
}
xendev->ops->connected(xendev);
}
/*
* Teardown connection.
*
* Goes to Closed when done.
*/
static void xen_be_disconnect(struct XenDevice *xendev, enum xenbus_state state)
{
if (xendev->be_state != XenbusStateClosing &&
xendev->be_state != XenbusStateClosed &&
xendev->ops->disconnect) {
xendev->ops->disconnect(xendev);
}
if (xendev->be_state != state) {
xen_be_set_state(xendev, state);
}
}
/*
* Try to reset xendev, for reconnection by another frontend instance.
*/
static int xen_be_try_reset(struct XenDevice *xendev)
{
if (xendev->fe_state != XenbusStateInitialising) {
return -1;
}
xen_be_printf(xendev, 1, "device reset (for re-connect)\n");
xen_be_set_state(xendev, XenbusStateInitialising);
return 0;
}
/*
* state change dispatcher function
*/
void xen_be_check_state(struct XenDevice *xendev)
{
int rc = 0;
/* frontend may request shutdown from almost anywhere */
if (xendev->fe_state == XenbusStateClosing ||
xendev->fe_state == XenbusStateClosed) {
xen_be_disconnect(xendev, xendev->fe_state);
return;
}
/* check for possible backend state transitions */
for (;;) {
switch (xendev->be_state) {
case XenbusStateUnknown:
rc = xen_be_try_setup(xendev);
break;
case XenbusStateInitialising:
rc = xen_be_try_init(xendev);
break;
case XenbusStateInitWait:
rc = xen_be_try_initialise(xendev);
break;
case XenbusStateConnected:
/* xendev->be_state doesn't change */
xen_be_try_connected(xendev);
rc = -1;
break;
case XenbusStateClosed:
rc = xen_be_try_reset(xendev);
break;
default:
rc = -1;
}
if (rc != 0) {
break;
}
}
}
/* ------------------------------------------------------------- */
static int xenstore_scan(const char *type, int dom, struct XenDevOps *ops)
{
struct XenDevice *xendev;
char path[XEN_BUFSIZE], token[XEN_BUFSIZE];
char **dev = NULL, *dom0;
unsigned int cdev, j;
/* setup watch */
dom0 = xs_get_domain_path(xenstore, 0);
snprintf(token, sizeof(token), "be:%p:%d:%p", type, dom, ops);
snprintf(path, sizeof(path), "%s/backend/%s/%d", dom0, type, dom);
free(dom0);
if (!xs_watch(xenstore, path, token)) {
xen_be_printf(NULL, 0, "xen be: watching backend path (%s) failed\n", path);
return -1;
}
/* look for backends */
dev = xs_directory(xenstore, 0, path, &cdev);
if (!dev) {
return 0;
}
for (j = 0; j < cdev; j++) {
xendev = xen_be_get_xendev(type, dom, atoi(dev[j]), ops);
if (xendev == NULL) {
continue;
}
xen_be_check_state(xendev);
}
free(dev);
return 0;
}
static void xenstore_update_be(char *watch, char *type, int dom,
struct XenDevOps *ops)
{
struct XenDevice *xendev;
char path[XEN_BUFSIZE], *dom0, *bepath;
unsigned int len, dev;
dom0 = xs_get_domain_path(xenstore, 0);
len = snprintf(path, sizeof(path), "%s/backend/%s/%d", dom0, type, dom);
free(dom0);
if (strncmp(path, watch, len) != 0) {
return;
}
if (sscanf(watch+len, "/%u/%255s", &dev, path) != 2) {
strcpy(path, "");
if (sscanf(watch+len, "/%u", &dev) != 1) {
dev = -1;
}
}
if (dev == -1) {
return;
}
xendev = xen_be_get_xendev(type, dom, dev, ops);
if (xendev != NULL) {
bepath = xs_read(xenstore, 0, xendev->be, &len);
if (bepath == NULL) {
xen_be_del_xendev(dom, dev);
} else {
free(bepath);
xen_be_backend_changed(xendev, path);
xen_be_check_state(xendev);
}
}
}
static void xenstore_update_fe(char *watch, struct XenDevice *xendev)
{
char *node;
unsigned int len;
len = strlen(xendev->fe);
if (strncmp(xendev->fe, watch, len) != 0) {
return;
}
if (watch[len] != '/') {
return;
}
node = watch + len + 1;
xen_be_frontend_changed(xendev, node);
xen_be_check_state(xendev);
}
static void xenstore_update(void *unused)
{
char **vec = NULL;
intptr_t type, ops, ptr;
unsigned int dom, count;
vec = xs_read_watch(xenstore, &count);
if (vec == NULL) {
goto cleanup;
}
if (sscanf(vec[XS_WATCH_TOKEN], "be:%" PRIxPTR ":%d:%" PRIxPTR,
&type, &dom, &ops) == 3) {
xenstore_update_be(vec[XS_WATCH_PATH], (void*)type, dom, (void*)ops);
}
if (sscanf(vec[XS_WATCH_TOKEN], "fe:%" PRIxPTR, &ptr) == 1) {
xenstore_update_fe(vec[XS_WATCH_PATH], (void*)ptr);
}
cleanup:
free(vec);
}
static void xen_be_evtchn_event(void *opaque)
{
struct XenDevice *xendev = opaque;
evtchn_port_t port;
port = xc_evtchn_pending(xendev->evtchndev);
if (port != xendev->local_port) {
xen_be_printf(xendev, 0, "xc_evtchn_pending returned %d (expected %d)\n",
port, xendev->local_port);
return;
}
xc_evtchn_unmask(xendev->evtchndev, port);
if (xendev->ops->event) {
xendev->ops->event(xendev);
}
}
/* -------------------------------------------------------------------- */
int xen_be_init(void)
{
xenstore = xs_daemon_open();
if (!xenstore) {
xen_be_printf(NULL, 0, "can't connect to xenstored\n");
return -1;
}
if (qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, NULL) < 0) {
goto err;
}
if (xen_xc == XC_HANDLER_INITIAL_VALUE) {
/* Check if xen_init() have been called */
goto err;
}
return 0;
err:
qemu_set_fd_handler(xs_fileno(xenstore), NULL, NULL, NULL);
xs_daemon_close(xenstore);
xenstore = NULL;
return -1;
}
int xen_be_register(const char *type, struct XenDevOps *ops)
{
return xenstore_scan(type, xen_domid, ops);
}
int xen_be_bind_evtchn(struct XenDevice *xendev)
{
if (xendev->local_port != -1) {
return 0;
}
xendev->local_port = xc_evtchn_bind_interdomain
(xendev->evtchndev, xendev->dom, xendev->remote_port);
if (xendev->local_port == -1) {
xen_be_printf(xendev, 0, "xc_evtchn_bind_interdomain failed\n");
return -1;
}
xen_be_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
qemu_set_fd_handler(xc_evtchn_fd(xendev->evtchndev),
xen_be_evtchn_event, NULL, xendev);
return 0;
}
void xen_be_unbind_evtchn(struct XenDevice *xendev)
{
if (xendev->local_port == -1) {
return;
}
qemu_set_fd_handler(xc_evtchn_fd(xendev->evtchndev), NULL, NULL, NULL);
xc_evtchn_unbind(xendev->evtchndev, xendev->local_port);
xen_be_printf(xendev, 2, "unbind evtchn port %d\n", xendev->local_port);
xendev->local_port = -1;
}
int xen_be_send_notify(struct XenDevice *xendev)
{
return xc_evtchn_notify(xendev->evtchndev, xendev->local_port);
}
/*
* msg_level:
* 0 == errors (stderr + logfile).
* 1 == informative debug messages (logfile only).
* 2 == noisy debug messages (logfile only).
* 3 == will flood your log (logfile only).
*/
void xen_be_printf(struct XenDevice *xendev, int msg_level, const char *fmt, ...)
{
va_list args;
if (xendev) {
if (msg_level > xendev->debug) {
return;
}
qemu_log("xen be: %s: ", xendev->name);
if (msg_level == 0) {
fprintf(stderr, "xen be: %s: ", xendev->name);
}
} else {
if (msg_level > debug) {
return;
}
qemu_log("xen be core: ");
if (msg_level == 0) {
fprintf(stderr, "xen be core: ");
}
}
va_start(args, fmt);
qemu_log_vprintf(fmt, args);
va_end(args);
if (msg_level == 0) {
va_start(args, fmt);
vfprintf(stderr, fmt, args);
va_end(args);
}
qemu_log_flush();
}
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