qemu/hw/xen_backend.c
John Haxby 384087b2fe Introduce a new 'connected' xendev op called when Connected.
Rename the existing xendev 'connect' op to 'initialised' and introduce
a new 'connected' op.  This new op, if defined, is called when the
backend is connected.  Note that since there is no state transition this
may be called more than once.

Signed-off-by: John Haxby <john.haxby@oracle.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
2011-09-09 13:13:16 +00:00

786 lines
21 KiB
C

/*
* 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/>.
*/
/*
* 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 <xs.h>
#include <xenctrl.h>
#include <xen/grant_table.h>
#include "hw.h"
#include "qemu-char.h"
#include "qemu-log.h"
#include "xen_backend.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;
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;
}
if (0) {
/* FIXME: detect devices being deleted from xenstore ... */
xen_be_del_xendev(dom, dev);
}
xendev = xen_be_get_xendev(type, dom, dev, ops);
if (xendev != NULL) {
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();
}