xen/xl-save-pc.patch

References: bug#1176189

Usage of xl save -p|-c will suspend the domU.
As a result the monitoring xl process with get a LIBXL_EVENT_TYPE_DOMAIN_SHUTDOWN/LIBXL_SHUTDOWN_REASON_SUSPEND event.
This will cause it to exit because it does not know the -p/-c flags were used to keep the domU active.
As a result the final shutdown will not destroy the domU.

Write a flag to xenstore to let the monitoring process know about the usage of -p/-c.
Remove the flag once the suspend is done.

Recognize the flag in the monitoring process.
Keep going if the flag is seen.
Watch again for @releaseDomain events.
Keep going if the event type and shutdown reason remains the same.
---
 tools/xl/Makefile         |  3 ++-
 tools/xl/xl.h             |  1 +
 tools/xl/xl_saverestore.c | 15 ++++++++++++
 tools/xl/xl_vmcontrol.c   | 48 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 66 insertions(+), 1 deletion(-)

--- a/tools/xl/Makefile
+++ b/tools/xl/Makefile
@@ -26,6 +26,7 @@ XL_OBJS += xl_vmcontrol.o xl_saverestore
 XL_OBJS += xl_vdispl.o xl_vsnd.o xl_vkb.o
 
 $(XL_OBJS): CFLAGS += $(CFLAGS_libxentoollog)
+$(XL_OBJS): CFLAGS += $(CFLAGS_libxenstore)
 $(XL_OBJS): CFLAGS += $(CFLAGS_XL)
 $(XL_OBJS): CFLAGS += -include $(XEN_ROOT)/tools/config.h # libxl_json.h needs it.
 
--- a/tools/xl/xl.h
+++ b/tools/xl/xl.h
@@ -306,6 +306,7 @@ typedef enum {
     DOMAIN_RESTART_SUSPENDED,    /* Domain suspended - keep looping */
 } domain_restart_type;
 
+#define XL_SAVE_PAUSE_CHECKPOINT "suse-xl-save-pc"
 extern void printf_info_sexp(int domid, libxl_domain_config *d_config, FILE *fh);
 extern void apply_global_affinity_masks(libxl_domain_type type,
                                         libxl_bitmap *vcpu_affinity_array,
--- a/tools/xl/xl_saverestore.c
+++ b/tools/xl/xl_saverestore.c
@@ -21,6 +21,7 @@
 #include <time.h>
 #include <unistd.h>
 
+#include <xenstore.h>
 #include <libxl.h>
 #include <libxl_utils.h>
 #include <libxlutil.h>
@@ -127,6 +128,8 @@ static int save_domain(uint32_t domid, i
                        const char *filename, int checkpoint,
                        int leavepaused, const char *override_config_file)
 {
+    struct xs_handle *xsh = NULL;
+    char path[80];
     int fd;
     uint8_t *config_data;
     int config_len;
@@ -143,12 +146,24 @@ static int save_domain(uint32_t domid, i
         fprintf(stderr, "Failed to open temp file %s for writing\n", filename);
         exit(EXIT_FAILURE);
     }
+    if (leavepaused || checkpoint)
+    {
+        snprintf(path, sizeof(path), "/libxl/%u/" XL_SAVE_PAUSE_CHECKPOINT, domid);
+        xsh = xs_open(0);
+        if (xsh)
+            xs_write(xsh, XBT_NULL, path, leavepaused ? "p" : "c", 1);
+    }
 
     save_domain_core_writeconfig(fd, filename, config_data, config_len);
 
     int rc = libxl_domain_suspend(ctx, domid, fd, 0, NULL);
     close(fd);
 
+    if (xsh) {
+        xs_rm(xsh, XBT_NULL, path);
+        xs_close(xsh);
+    }
+
     if (rc < 0) {
         fprintf(stderr, "Failed to save domain, resuming domain\n");
         libxl_domain_resume(ctx, domid, 1, 0);
--- a/tools/xl/xl_vmcontrol.c
+++ b/tools/xl/xl_vmcontrol.c
@@ -22,6 +22,7 @@
 #include <time.h>
 #include <unistd.h>
 
+#include <xenstore.h>
 #include <libxl.h>
 #include <libxl_utils.h>
 #include <libxlutil.h>
@@ -706,6 +707,10 @@ int create_domain(struct domain_create *
     int migrate_fd = dom_info->migrate_fd;
     bool config_in_json;
 
+    libxl_event_type type = 0;
+    uint8_t shutdown_reason = 0;
+    bool is_in_suspend = false;
+
     int i;
     int need_daemon = daemonize;
     int ret, rc;
@@ -1073,6 +1078,24 @@ start:
         ret = domain_wait_event(domid, &event);
         if (ret) goto out;
 
+        if (is_in_suspend) {
+            if ( type == event->type && event->u.domain_shutdown.shutdown_reason == shutdown_reason) {
+                struct timespec req = { .tv_nsec = 123456789, };
+                libxl_evdisable_domain_death(ctx, deathw);
+                deathw = NULL;
+                ret = libxl_evenable_domain_death(ctx, domid, 0, &deathw);
+                if (ret) goto out;
+                libxl_event_free(ctx, event);
+                LOG("Domain %u still suspended", domid);
+                nanosleep(&req, NULL);
+                continue;
+            }
+            is_in_suspend = false;
+            LOG("Domain %u left suspend state", domid);
+        }
+        type = event->type;
+        shutdown_reason = event->u.domain_shutdown.shutdown_reason;
+
         switch (event->type) {
 
         case LIBXL_EVENT_TYPE_DOMAIN_SHUTDOWN:
@@ -1134,10 +1157,34 @@ start:
                 goto start;
 
             case DOMAIN_RESTART_NONE:
+                {
+                struct xs_handle *xsh = xs_open(0);
+
+                if (xsh) {
+                    char path[80];
+                    unsigned int len = 0;
+                    char *val;
+
+                    snprintf(path, sizeof(path), "/libxl/%u/" XL_SAVE_PAUSE_CHECKPOINT, domid);
+                    val = xs_read(xsh, XBT_NULL, path, &len);
+                    xs_close(xsh);
+                    LOG("Got %p '%s' from %s, len %u", val, val ?:"", path, len);
+                    free(val);
+                    if (val)
+                    {
+                        is_in_suspend = true;
+                        libxl_evdisable_domain_death(ctx, deathw);
+                        deathw = NULL;
+                        ret = libxl_evenable_domain_death(ctx, domid, 0, &deathw);
+                        if (ret) goto out;
+                        break;
+                    }
+                }
                 LOG("Done. Exiting now");
                 libxl_event_free(ctx, event);
                 ret = 0;
                 goto out;
+                }
 
             case DOMAIN_RESTART_SUSPENDED:
                 LOG("Continue waiting for domain %u", domid);