[PATCH 2 of 3] tools/libxl: suspend/postflush/commit callbacks

[rshriram@cs.ubc.ca]

# HG changeset patch
# User Shriram Rajagopalan <rshriram@cs.ubc.ca>
# Date 1327358640 28800
# Node ID 0446591bee86eb4e767d75b70c885549c7a3cfef
# Parent  11fb1dfda7de4d6759dec87d80cd16cf137f7369
tools/libxl: suspend/postflush/commit callbacks

 * Add libxl callbacks for Remus checkpoint suspend, postflush (aka resume)
   and checkpoint commit callbacks.
 * suspend callback just bounces off libxl__domain_suspend_common_callback
 * resume callback directly calls xc_domain_resume instead of re-using
   libxl_domain_resume (as the latter does not set the fast suspend argument
   to xc_domain_resume - aka suspend_cancel support).
 * commit callback just sleeps for the checkpoint interval (for the moment).

 * Future patches will augument these callbacks with more functionalities like
   issuing network buffer plug/unplug commands, disk checkpoint commands, etc.

Signed-off-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>

diff -r 11fb1dfda7de -r 0446591bee86 tools/libxl/libxl.c
--- a/tools/libxl/libxl.c	Mon Jan 23 14:43:58 2012 -0800
+++ b/tools/libxl/libxl.c	Mon Jan 23 14:44:00 2012 -0800
@@ -475,7 +475,9 @@
     int debug = info != NULL && info->flags & XL_SUSPEND_DEBUG;
     int rc = 0;
 
-    rc = libxl__domain_suspend_common(gc, domid, fd, type, live, debug);
+    rc = libxl__domain_suspend_common(gc, domid, fd, type, live, debug,
+                                      /* No Remus */ NULL);
+
     if (!rc && type == LIBXL_DOMAIN_TYPE_HVM)
         rc = libxl__domain_save_device_model(gc, domid, fd, /* No Remus */ 0);
     GC_FREE;
diff -r 11fb1dfda7de -r 0446591bee86 tools/libxl/libxl.h
--- a/tools/libxl/libxl.h	Mon Jan 23 14:43:58 2012 -0800
+++ b/tools/libxl/libxl.h	Mon Jan 23 14:44:00 2012 -0800
@@ -212,6 +212,12 @@
     int (*suspend_callback)(void *, int);
 } libxl_domain_suspend_info;
 
+typedef struct {
+    int interval;
+    int blackhole;
+    int compression;
+} libxl_domain_remus_info;
+
 enum {
     ERROR_NONSPECIFIC = -1,
     ERROR_VERSION = -2,
diff -r 11fb1dfda7de -r 0446591bee86 tools/libxl/libxl_dom.c
--- a/tools/libxl/libxl_dom.c	Mon Jan 23 14:43:58 2012 -0800
+++ b/tools/libxl/libxl_dom.c	Mon Jan 23 14:44:00 2012 -0800
@@ -395,6 +395,8 @@
     int hvm;
     unsigned int flags;
     int guest_responded;
+    int save_fd; /* Migration stream fd (for Remus) */
+    int interval; /* remus checkpoint interval */
 };
 
 static int libxl__domain_suspend_common_switch_qemu_logdirty(int domid, unsigned int enable, void *data)
@@ -581,9 +583,69 @@
     return 0;
 }
 
+static int libxl__remus_domain_suspend_callback(void *data)
+{
+    struct suspendinfo *si = data;
+
+    if (libxl__domain_suspend_common_callback(data)) {
+        if (si->hvm) {
+            if (!libxl__remus_domain_suspend_qemu(si->gc, si->domid))
+                return 1;
+            else
+                return 0;
+        }
+        return 1;
+    }
+    return 0;
+}
+
+static int libxl__remus_domain_resume_callback(void *data)
+{
+    struct suspendinfo *si = data;
+    libxl_ctx *ctx = libxl__gc_owner(si->gc);
+
+    /* Assumes that SUSPEND_CANCEL is available - just like
+     * xm version of Remus. Without that, remus wont work.
+     * Since libxl_domain_resume calls xc_domain_resume with
+     * fast_suspend = 0, we cant re-use that api.
+     */
+    if (xc_domain_resume(ctx->xch, si->domid, 1)) {
+        LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
+                   "xc_domain_resume failed for domain %u",
+                   si->domid);
+        return 0;
+    }
+    if (!xs_resume_domain(ctx->xsh, si->domid)) {
+        LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
+                   "xs_resume_domain failed for domain %u",
+                   si->domid);
+        return 0;
+    }
+
+    if (si->hvm) {
+        if (libxl__remus_domain_resume_qemu(si->gc, si->domid))
+            return 0;
+    }
+    return 1;
+}
+
+/* For now, just sleep. Later, we need to release disk/netbuf */
+static int libxl__remus_domain_checkpoint_callback(void *data)
+{
+    struct suspendinfo *si = data;
+
+    if (si->hvm && libxl__domain_save_device_model(si->gc, si->domid,
+                                                   si->save_fd, 1))
+            return 0;
+
+    usleep(si->interval * 1000);
+    return 1;
+}
+
 int libxl__domain_suspend_common(libxl__gc *gc, uint32_t domid, int fd,
                                  libxl_domain_type type,
-                                 int live, int debug)
+                                 int live, int debug,
+                                 const libxl_domain_remus_info *r_info)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
     int flags;
@@ -614,10 +676,20 @@
         return ERROR_INVAL;
     }
 
+    memset(&si, 0, sizeof(si));
     flags = (live) ? XCFLAGS_LIVE : 0
           | (debug) ? XCFLAGS_DEBUG : 0
           | (hvm) ? XCFLAGS_HVM : 0;
 
+    if (r_info != NULL) {
+        si.interval = r_info->interval;
+        if (r_info->compression)
+            flags |= XCFLAGS_CHECKPOINT_COMPRESS;
+        si.save_fd = fd;
+    }
+    else
+        si.save_fd = -1;
+
     si.domid = domid;
     si.flags = flags;
     si.hvm = hvm;
@@ -641,7 +713,13 @@
     }
 
     memset(&callbacks, 0, sizeof(callbacks));
-    callbacks.suspend = libxl__domain_suspend_common_callback;
+    if (r_info != NULL) {
+        callbacks.suspend = libxl__remus_domain_suspend_callback;
+        callbacks.postcopy = libxl__remus_domain_resume_callback;
+        callbacks.checkpoint = libxl__remus_domain_checkpoint_callback;
+    } else
+        callbacks.suspend = libxl__domain_suspend_common_callback;
+
     callbacks.switch_qemu_logdirty = libxl__domain_suspend_common_switch_qemu_logdirty;
     callbacks.data = &si;
 
diff -r 11fb1dfda7de -r 0446591bee86 tools/libxl/libxl_internal.h
--- a/tools/libxl/libxl_internal.h	Mon Jan 23 14:43:58 2012 -0800
+++ b/tools/libxl/libxl_internal.h	Mon Jan 23 14:44:00 2012 -0800
@@ -272,7 +272,8 @@
                                          int fd);
 _hidden int libxl__domain_suspend_common(libxl__gc *gc, uint32_t domid, int fd,
                                          libxl_domain_type type,
-                                         int live, int debug);
+                                         int live, int debug,
+                                         const libxl_domain_remus_info *r_info);
 _hidden const char *libxl__device_model_savefile(libxl__gc *gc, uint32_t domid);
 _hidden int libxl__domain_save_device_model(libxl__gc *gc, uint32_t domid, int fd,
                                             int remus);