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qemu/hw/xen/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 "qemu/osdep.h"
#include <sys/signal.h>
#include "hw/hw.h"
#include "hw/sysbus.h"
#include "hw/boards.h"
#include "qemu/log.h"
#include "qapi/error.h"
#include "hw/xen/xen_backend.h"
#include "hw/xen/xen_pvdev.h"
#include "monitor/qdev.h"
#include <xen/grant_table.h>
DeviceState *xen_sysdev;
BusState *xen_sysbus;
/* ------------------------------------------------------------- */
/* public */
struct xs_handle *xenstore = NULL;
const char *xen_protocol;
bool xen_feature_grant_copy;
/* private */
static int debug;
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);
}
int xenstore_write_be_int64(struct XenDevice *xendev, const char *node, int64_t ival)
{
return xenstore_write_int64(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);
}
int xenstore_read_fe_uint64(struct XenDevice *xendev, const char *node,
uint64_t *uval)
{
return xenstore_read_uint64(xendev->fe, node, uval);
}
/* ------------------------------------------------------------- */
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_pv_printf(xendev, 1, "backend state: %s -> %s\n",
xenbus_strstate(xendev->be_state), xenbus_strstate(state));
xendev->be_state = state;
return 0;
}
/*
* 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;
xendev = xen_pv_find_xendev(type, dom, dev);
if (xendev) {
return xendev;
}
/* init new xendev */
xendev = g_malloc0(ops->size);
object_initialize(&xendev->qdev, ops->size, TYPE_XENBACKEND);
OBJECT(xendev)->free = g_free;
qdev_set_parent_bus(DEVICE(xendev), xen_sysbus);
qdev_set_id(DEVICE(xendev), g_strdup_printf("xen-%s-%d", type, dev));
qdev_init_nofail(DEVICE(xendev));
object_unref(OBJECT(xendev));
xendev->type = type;
xendev->dom = dom;
xendev->dev = dev;
xendev->ops = ops;
snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
xendev->type, xendev->dom, xendev->dev);
snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
xendev->type, xendev->dev);
xendev->debug = debug;
xendev->local_port = -1;
xendev->evtchndev = xenevtchn_open(NULL, 0);
if (xendev->evtchndev == NULL) {
xen_pv_printf(NULL, 0, "can't open evtchn device\n");
qdev_unplug(DEVICE(xendev), NULL);
return NULL;
}
qemu_set_cloexec(xenevtchn_fd(xendev->evtchndev));
if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
xendev->gnttabdev = xengnttab_open(NULL, 0);
if (xendev->gnttabdev == NULL) {
xen_pv_printf(NULL, 0, "can't open gnttab device\n");
xenevtchn_close(xendev->evtchndev);
qdev_unplug(DEVICE(xendev), NULL);
return NULL;
}
} else {
xendev->gnttabdev = NULL;
}
xen_pv_insert_xendev(xendev);
if (xendev->ops->alloc) {
xendev->ops->alloc(xendev);
}
return xendev;
}
/*
* 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_pv_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_pv_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_pv_printf(xendev, 1, "frontend protocol: %s\n",
xendev->protocol);
}
}
if (node) {
xen_pv_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_pv_printf(xendev, 0, "reading backend state failed\n");
return -1;
}
if (be_state != XenbusStateInitialising) {
xen_pv_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_pv_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_pv_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_pv_printf(xendev, 1, "not online\n");
return -1;
}
if (xendev->ops->init) {
rc = xendev->ops->init(xendev);
}
if (rc != 0) {
xen_pv_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_pv_printf(xendev, 2, "frontend not ready, ignoring\n");
} else {
xen_pv_printf(xendev, 2, "frontend not ready (yet)\n");
return -1;
}
}
if (xendev->ops->initialise) {
rc = xendev->ops->initialise(xendev);
}
if (rc != 0) {
xen_pv_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_pv_printf(xendev, 2, "frontend not ready, ignoring\n");
} else {
xen_pv_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_pv_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;
unsigned int cdev, j;
/* setup watch */
snprintf(token, sizeof(token), "be:%p:%d:%p", type, dom, ops);
snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
if (!xs_watch(xenstore, path, token)) {
xen_pv_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;
}
void xenstore_update_be(char *watch, char *type, int dom,
struct XenDevOps *ops)
{
struct XenDevice *xendev;
char path[XEN_BUFSIZE], *bepath;
unsigned int len, dev;
len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
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_pv_del_xendev(xendev);
} else {
free(bepath);
xen_be_backend_changed(xendev, path);
xen_be_check_state(xendev);
}
}
}
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);
}
/* -------------------------------------------------------------------- */
int xen_be_init(void)
{
xengnttab_handle *gnttabdev;
xenstore = xs_daemon_open();
if (!xenstore) {
xen_pv_printf(NULL, 0, "can't connect to xenstored\n");
return -1;
}
qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, NULL);
if (xen_xc == NULL || xen_fmem == NULL) {
/* Check if xen_init() have been called */
goto err;
}
gnttabdev = xengnttab_open(NULL, 0);
if (gnttabdev != NULL) {
if (xengnttab_grant_copy(gnttabdev, 0, NULL) == 0) {
xen_feature_grant_copy = true;
}
xengnttab_close(gnttabdev);
}
xen_sysdev = qdev_create(NULL, TYPE_XENSYSDEV);
qdev_init_nofail(xen_sysdev);
xen_sysbus = qbus_create(TYPE_XENSYSBUS, DEVICE(xen_sysdev), "xen-sysbus");
qbus_set_bus_hotplug_handler(xen_sysbus, &error_abort);
return 0;
err:
qemu_set_fd_handler(xs_fileno(xenstore), NULL, NULL, NULL);
xs_daemon_close(xenstore);
xenstore = NULL;
return -1;
}
static void xen_set_dynamic_sysbus(void)
{
Object *machine = qdev_get_machine();
ObjectClass *oc = object_get_class(machine);
MachineClass *mc = MACHINE_CLASS(oc);
machine_class_allow_dynamic_sysbus_dev(mc, TYPE_XENSYSDEV);
}
int xen_be_register(const char *type, struct XenDevOps *ops)
{
char path[50];
int rc;
if (ops->backend_register) {
rc = ops->backend_register();
if (rc) {
return rc;
}
}
snprintf(path, sizeof(path), "device-model/%u/backends/%s", xen_domid,
type);
xenstore_mkdir(path, XS_PERM_NONE);
return xenstore_scan(type, xen_domid, ops);
}
void xen_be_register_common(void)
{
xen_set_dynamic_sysbus();
xen_be_register("console", &xen_console_ops);
xen_be_register("vkbd", &xen_kbdmouse_ops);
xen_be_register("qdisk", &xen_blkdev_ops);
#ifdef CONFIG_VIRTFS
xen_be_register("9pfs", &xen_9pfs_ops);
#endif
#ifdef CONFIG_USB_LIBUSB
xen_be_register("qusb", &xen_usb_ops);
#endif
}
int xen_be_bind_evtchn(struct XenDevice *xendev)
{
if (xendev->local_port != -1) {
return 0;
}
xendev->local_port = xenevtchn_bind_interdomain
(xendev->evtchndev, xendev->dom, xendev->remote_port);
if (xendev->local_port == -1) {
xen_pv_printf(xendev, 0, "xenevtchn_bind_interdomain failed\n");
return -1;
}
xen_pv_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev),
xen_pv_evtchn_event, NULL, xendev);
return 0;
}
static Property xendev_properties[] = {
DEFINE_PROP_END_OF_LIST(),
};
static void xendev_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->props = xendev_properties;
set_bit(DEVICE_CATEGORY_MISC, dc->categories);
/* xen-backend devices can be plugged/unplugged dynamically */
dc->user_creatable = true;
}
static const TypeInfo xendev_type_info = {
.name = TYPE_XENBACKEND,
.parent = TYPE_XENSYSDEV,
.class_init = xendev_class_init,
.instance_size = sizeof(struct XenDevice),
};
static void xen_sysbus_class_init(ObjectClass *klass, void *data)
{
HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
hc->unplug = qdev_simple_device_unplug_cb;
}
static const TypeInfo xensysbus_info = {
.name = TYPE_XENSYSBUS,
.parent = TYPE_BUS,
.class_init = xen_sysbus_class_init,
.interfaces = (InterfaceInfo[]) {
{ TYPE_HOTPLUG_HANDLER },
{ }
}
};
static int xen_sysdev_init(SysBusDevice *dev)
{
return 0;
}
static Property xen_sysdev_properties[] = {
{/* end of property list */},
};
static void xen_sysdev_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
k->init = xen_sysdev_init;
dc->props = xen_sysdev_properties;
dc->bus_type = TYPE_XENSYSBUS;
}
static const TypeInfo xensysdev_info = {
.name = TYPE_XENSYSDEV,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(SysBusDevice),
.class_init = xen_sysdev_class_init,
};
static void xenbe_register_types(void)
{
type_register_static(&xensysbus_info);
type_register_static(&xensysdev_info);
type_register_static(&xendev_type_info);
}
type_init(xenbe_register_types)
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