--- /dev/null
+/*
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+/*
+ * 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 "xen_backend.h"
+
+/* ------------------------------------------------------------- */
+
+/* public */
+int xen_xc;
+struct xs_handle *xenstore = NULL;
+const char *xen_protocol;
+
+/* private */
+static TAILQ_HEAD(XenDeviceHead, XenDevice) xendevs = TAILQ_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;
+
+ snprintf(abspath, sizeof(abspath), "%s/%s", base, node);
+ return xs_read(xenstore, 0, abspath, &len);
+}
+
+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;
+ qemu_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;
+
+ TAILQ_FOREACH(xendev, &xendevs, next) {
+ if (xendev->dom != dom)
+ continue;
+ if (xendev->dev != dev)
+ continue;
+ if (0 != strcmp(xendev->type, type))
+ 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 = qemu_mallocz(ops->size);
+ if (!xendev)
+ return NULL;
+ 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 = xc_evtchn_open();
+ if (xendev->evtchndev < 0) {
+ fprintf(stderr, "can't open evtchn device\n");
+ qemu_free(xendev);
+ return NULL;
+ }
+ fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
+
+ if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
+ xendev->gnttabdev = xc_gnttab_open();
+ if (xendev->gnttabdev < 0) {
+ fprintf(stderr, "can't open gnttab device\n");
+ xc_evtchn_close(xendev->evtchndev);
+ qemu_free(xendev);
+ return NULL;
+ }
+ } else {
+ xendev->gnttabdev = -1;
+ }
+
+ TAILQ_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 TAILQ_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);
+ qemu_free(xendev->fe);
+ }
+
+ if (xendev->evtchndev >= 0)
+ xc_evtchn_close(xendev->evtchndev);
+ if (xendev->gnttabdev >= 0)
+ xc_gnttab_close(xendev->gnttabdev);
+
+ TAILQ_REMOVE(&xendevs, xendev, next);
+ qemu_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 (NULL == node || 0 == strcmp(node, "online")) {
+ if (-1 == xenstore_read_be_int(xendev, "online", &xendev->online))
+ 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 (NULL == node || 0 == strcmp(node, "state")) {
+ if (-1 == xenstore_read_fe_int(xendev, "state", &fe_state))
+ 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 (NULL == node || 0 == strcmp(node, "protocol")) {
+ qemu_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 (-1 == xenstore_read_be_int(xendev, "state", &be_state)) {
+ 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 (NULL == xendev->fe) {
+ 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 (0 != rc) {
+ 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 connect 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_connect(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->connect)
+ rc = xendev->ops->connect(xendev);
+ if (0 != rc) {
+ xen_be_printf(xendev, 0, "connect() failed\n");
+ return rc;
+ }
+
+ xen_be_set_state(xendev, XenbusStateConnected);
+ return 0;
+}
+
+/*
+ * 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_connect(xendev);
+ break;
+ case XenbusStateClosed:
+ rc = xen_be_try_reset(xendev);
+ break;
+ default:
+ rc = -1;
+ }
+ if (0 != rc)
+ 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)) {
+ fprintf(stderr, "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 (NULL == xendev)
+ continue;
+ xen_be_check_state(xendev);
+ }
+ qemu_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 (0 != strncmp(path, watch, len))
+ return;
+ if (2 != sscanf(watch+len, "/%u/%255s", &dev, path)) {
+ strcpy(path, "");
+ if (1 != sscanf(watch+len, "/%u", &dev))
+ dev = -1;
+ }
+ if (-1 == dev)
+ 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 (NULL != xendev) {
+ 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 (0 != strncmp(xendev->fe, watch, len))
+ 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 (NULL == vec)
+ goto cleanup;
+
+ if (3 == sscanf(vec[XS_WATCH_TOKEN], "be:%" PRIxPTR ":%d:%" PRIxPTR,
+ &type, &dom, &ops))
+ xenstore_update_be(vec[XS_WATCH_PATH], (void*)type, dom, (void*)ops);
+ if (1 == sscanf(vec[XS_WATCH_TOKEN], "fe:%" PRIxPTR, &ptr))
+ xenstore_update_fe(vec[XS_WATCH_PATH], (void*)ptr);
+
+cleanup:
+ qemu_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) {
+ fprintf(stderr, "can't connect to xenstored\n");
+ return -1;
+ }
+
+ if (qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, NULL) < 0)
+ goto err;
+
+ xen_xc = xc_interface_open();
+ if (-1 == xen_xc) {
+ fprintf(stderr, "can't open xen interface\n");
+ 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 (-1 == xendev->local_port) {
+ 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.
+ * 1 == informative debug messages.
+ * 2 == noisy debug messages.
+ * 3 == will flood your log.
+ */
+void xen_be_printf(struct XenDevice *xendev, int msg_level, const char *fmt, ...)
+{
+ va_list args;
+
+ if (msg_level > xendev->debug)
+ return;
+ fprintf(stderr, "xen be: %s: ", xendev->name);
+ va_start(args, fmt);
+ vfprintf(stderr, fmt, args);
+ va_end(args);
+}
projects / qemu-xen-3.4-testing.git / commitdiff