# HG changeset patch
# User Brendan Cully <brendan@xxxxxxxxx>
# Date 1215120748 25200
# Node ID 3e1d3cb03e8bf2b2f44066e6d7ec9729995d1db1
# Parent ca55cf40cd134b41812c8c4b851d7df51031de07
Teach xc_save to use event-channel-based domain suspend if available.
If the guest provides a suspend event channel through xenstore,
xc_save will use it in preference to the old xenstore-based method.
Xend is still informed when the domain has suspended so that it can
perform device migration in parallel with last-round migration.
Signed-off-by: Brendan Cully <brendan@xxxxxxxxx>
diff --git a/tools/python/xen/xend/XendCheckpoint.py
b/tools/python/xen/xend/XendCheckpoint.py
--- a/tools/python/xen/xend/XendCheckpoint.py
+++ b/tools/python/xen/xend/XendCheckpoint.py
@@ -108,6 +108,7 @@
log.debug("Suspending %d ...", dominfo.getDomid())
dominfo.shutdown('suspend')
dominfo.waitForShutdown()
+ if line in ('suspend', 'suspended'):
dominfo.migrateDevices(network, dst, DEV_MIGRATE_STEP2,
domain_name)
log.info("Domain %d suspended.", dominfo.getDomid())
@@ -116,6 +117,7 @@
if hvm:
dominfo.image.saveDeviceModel()
+ if line == "suspend":
tochild.write("done\n")
tochild.flush()
log.debug('Written done')
diff --git a/tools/xcutils/xc_save.c b/tools/xcutils/xc_save.c
--- a/tools/xcutils/xc_save.c
+++ b/tools/xcutils/xc_save.c
@@ -23,11 +23,18 @@
#include <xenctrl.h>
#include <xenguest.h>
+static struct suspendinfo {
+ int xce; /* event channel handle */
+
+ int suspend_evtchn;
+ int suspended_evtchn;
+} si;
+
/**
* Issue a suspend request through stdout, and receive the acknowledgement
* from stdin. This is handled by XendCheckpoint in the Python layer.
*/
-static int suspend(int domid)
+static int compat_suspend(int domid)
{
char ans[30];
@@ -36,6 +43,131 @@
return (fgets(ans, sizeof(ans), stdin) != NULL &&
!strncmp(ans, "done\n", 5));
+}
+
+static int suspend_evtchn_release(int xc, int domid)
+{
+ if (si.suspended_evtchn >= 0) {
+ xc_dom_subscribe(xc, domid, 0);
+ xc_evtchn_unbind(si.xce, si.suspended_evtchn);
+ si.suspended_evtchn = -1;
+ }
+ if (si.suspend_evtchn >= 0) {
+ xc_evtchn_unbind(si.xce, si.suspend_evtchn);
+ si.suspend_evtchn = -1;
+ }
+ if (si.xce >= 0) {
+ xc_evtchn_close(si.xce);
+ si.xce = -1;
+ }
+
+ return 0;
+}
+
+static int suspend_evtchn_init(int xc, int domid)
+{
+ struct xs_handle *xs;
+ char path[128];
+ char *portstr;
+ unsigned int plen;
+ int port;
+ int rc;
+
+ si.xce = -1;
+ si.suspend_evtchn = -1;
+ si.suspended_evtchn = -1;
+
+ xs = xs_daemon_open();
+ if (!xs) {
+ errx(1, "failed to get xenstore handle");
+ return -1;
+ }
+ sprintf(path, "/local/domain/%d/device/suspend/event-channel", domid);
+ portstr = xs_read(xs, XBT_NULL, path, &plen);
+ xs_daemon_close(xs);
+
+ if (!portstr || !plen) {
+ warnx("could not read suspend event channel");
+ return -1;
+ }
+
+ port = atoi(portstr);
+ free(portstr);
+
+ si.xce = xc_evtchn_open();
+ if (si.xce < 0) {
+ errx(1, "failed to open event channel handle");
+ goto cleanup;
+ }
+
+ si.suspend_evtchn = xc_evtchn_bind_interdomain(si.xce, domid, port);
+ if (si.suspend_evtchn < 0) {
+ errx(1, "failed to bind suspend event channel: %d",
+ si.suspend_evtchn);
+ goto cleanup;
+ }
+
+ si.suspended_evtchn = xc_evtchn_bind_unbound_port(si.xce, domid);
+ if (si.suspended_evtchn < 0) {
+ errx(1, "failed to allocate suspend notification port: %d",
+ si.suspended_evtchn);
+ goto cleanup;
+ }
+
+ rc = xc_dom_subscribe(xc, domid, si.suspended_evtchn);
+ if (rc < 0) {
+ errx(1, "failed to subscribe to domain: %d", rc);
+ goto cleanup;
+ }
+
+ return 0;
+
+ cleanup:
+ suspend_evtchn_release(xc, domid);
+
+ return -1;
+}
+
+/**
+ * Issue a suspend request to a dedicated event channel in the guest, and
+ * receive the acknowledgement from the subscribe event channel. */
+static int evtchn_suspend(int domid)
+{
+ int xcefd;
+ int rc;
+
+ rc = xc_evtchn_notify(si.xce, si.suspend_evtchn);
+ if (rc < 0) {
+ errx(1, "failed to notify suspend request channel: %d", rc);
+ return 0;
+ }
+
+ xcefd = xc_evtchn_fd(si.xce);
+ do {
+ rc = xc_evtchn_pending(si.xce);
+ if (rc < 0) {
+ errx(1, "error polling suspend notification channel: %d", rc);
+ return 0;
+ }
+ } while (rc != si.suspended_evtchn);
+
+ /* harmless for one-off suspend */
+ if (xc_evtchn_unmask(si.xce, si.suspended_evtchn) < 0)
+ errx(1, "failed to unmask suspend notification channel: %d", rc);
+
+ /* notify xend that it can do device migration */
+ printf("suspended\n");
+ fflush(stdout);
+
+ return 1;
+}
+
+static int suspend(int domid)
+{
+ if (si.suspend_evtchn >= 0)
+ return evtchn_suspend(domid);
+
+ return compat_suspend(domid);
}
/* For HVM guests, there are two sources of dirty pages: the Xen shadow
@@ -188,9 +320,13 @@
max_f = atoi(argv[4]);
flags = atoi(argv[5]);
+ suspend_evtchn_init(xc_fd, domid);
+
ret = xc_domain_save(xc_fd, io_fd, domid, maxit, max_f, flags,
&suspend, !!(flags & XCFLAGS_HVM),
&init_qemu_maps, &qemu_flip_buffer);
+
+ suspend_evtchn_release(xc_fd, domid);
xc_interface_close(xc_fd);
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