[PATCH V8 10/39] cpr: cpr-enable option

[Steve Sistare]

Add the '-cpr-enable <mode>' command-line option as a pre-requisite for
using cpr-save and cpr-load for the mode.  Multiple -cpr-enable options
may be specified, one per mode.

Requiring -cpr-enable allows qemu to initialize objects differently, if
necessary, so that cpr-save is not blocked.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 hmp-commands.hx         |  4 ++++
 include/migration/cpr.h |  2 ++
 migration/cpr.c         | 22 ++++++++++++++++++++++
 qapi/cpr.json           |  4 ++++
 qemu-options.hx         | 10 ++++++++++
 softmmu/vl.c            |  8 ++++++++
 6 files changed, 50 insertions(+)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 9d9f984..d621968 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -370,6 +370,8 @@ SRST
   and does not require that guest RAM be saved in the file.  The caller must
   not modify guest block devices between cpr-save and cpr-load.
 
+  cpr-save requires that qemu was started with -cpr-enable for *mode*.
+
   If *mode* is 'reboot', the checkpoint remains valid after a host reboot.
   The guest RAM memory-backend should be shared and non-volatile across
   reboot, else it will be saved to the file.  To resume from the checkpoint,
@@ -391,6 +393,8 @@ SRST
   Load a virtual machine from the checkpoint file *filename* that was created
   earlier by the cpr-save command, and continue the VCPUs.  *mode* must match
   the mode specified for cpr-save.
+
+  cpr-load requires that qemu was started with -cpr-enable for *mode*.
 ERST
 
     {
diff --git a/include/migration/cpr.h b/include/migration/cpr.h
index dfe5a1d..f236cbf 100644
--- a/include/migration/cpr.h
+++ b/include/migration/cpr.h
@@ -10,8 +10,10 @@
 
 #include "qapi/qapi-types-cpr.h"
 
+void cpr_init(int modes);
 void cpr_set_mode(CprMode mode);
 CprMode cpr_get_mode(void);
+bool cpr_enabled(CprMode mode);
 
 #define CPR_MODE_ALL CPR_MODE__MAX
 
diff --git a/migration/cpr.c b/migration/cpr.c
index c1da784..76b9225 100644
--- a/migration/cpr.c
+++ b/migration/cpr.c
@@ -29,6 +29,18 @@ void cpr_set_mode(CprMode mode)
     cpr_mode = mode;
 }
 
+static int cpr_enabled_modes;
+
+void cpr_init(int modes)
+{
+    cpr_enabled_modes = modes;
+}
+
+bool cpr_enabled(CprMode mode)
+{
+    return !!(cpr_enabled_modes & BIT(mode));
+}
+
 static GSList *cpr_blockers[CPR_MODE__MAX];
 
 /*
@@ -110,6 +122,11 @@ void qmp_cpr_save(const char *filename, CprMode mode, 
Error **errp)
     QEMUFile *f;
     int saved_vm_running = runstate_is_running();
 
+    if (!(cpr_enabled_modes & BIT(mode))) {
+        error_setg(errp, "cpr mode is not enabled.  Use -cpr-enable.");
+        return;
+    }
+
     if (cpr_is_blocked(errp, mode)) {
         return;
     }
@@ -154,6 +171,11 @@ void qmp_cpr_load(const char *filename, CprMode mode, 
Error **errp)
     int ret;
     RunState state;
 
+    if (!(cpr_enabled_modes & BIT(mode))) {
+        error_setg(errp, "cpr mode is not enabled.  Use -cpr-enable.");
+        return;
+    }
+
     if (runstate_is_running()) {
         error_setg(errp, "cpr-load called for a running VM");
         return;
diff --git a/qapi/cpr.json b/qapi/cpr.json
index bdaabcb..11c6f88 100644
--- a/qapi/cpr.json
+++ b/qapi/cpr.json
@@ -30,6 +30,8 @@
 # and does not require that guest RAM be saved in the file.  The caller must
 # not modify guest block devices between cpr-save and cpr-load.
 #
+# cpr-save requires that qemu was started with -cpr-enable for @mode.
+#
 # If @mode is 'reboot', the checkpoint remains valid after a host reboot.
 # The guest RAM memory-backend should be shared and non-volatile across
 # reboot, else it will be saved to the file.  To resume from the checkpoint,
@@ -52,6 +54,8 @@
 # earlier by the cpr-save command, and continue the VCPUs.  @mode must match
 # the mode specified for cpr-save.
 #
+# cpr-load requires that qemu was started with -cpr-enable for @mode.
+#
 # @filename: name of checkpoint file
 # @mode: @CprMode mode
 #
diff --git a/qemu-options.hx b/qemu-options.hx
index 377d22f..6e51c33 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4483,6 +4483,16 @@ SRST
     an unmigratable state.
 ERST
 
+DEF("cpr-enable", HAS_ARG, QEMU_OPTION_cpr_enable, \
+    "-cpr-enable reboot    enable the cpr mode\n",
+    QEMU_ARCH_ALL)
+SRST
+``-cpr-enable reboot``
+    Enable the specified cpr mode.  May be supplied multiple times, once
+    per mode.  This is a pre-requisite for calling the cpr-save and cpr-load
+    commands.
+ERST
+
 DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
     "-nodefaults     don't create default devices\n", QEMU_ARCH_ALL)
 SRST
diff --git a/softmmu/vl.c b/softmmu/vl.c
index 54e920a..ce779cf 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -78,6 +78,7 @@
 #include "hw/i386/pc.h"
 #include "migration/misc.h"
 #include "migration/snapshot.h"
+#include "migration/cpr.h"
 #include "sysemu/tpm.h"
 #include "sysemu/dma.h"
 #include "hw/audio/soundhw.h"
@@ -2600,6 +2601,7 @@ void qemu_init(int argc, char **argv, char **envp)
     MachineClass *machine_class;
     bool userconfig = true;
     FILE *vmstate_dump_file = NULL;
+    int cpr_modes = 0;
 
     qemu_add_opts(&qemu_drive_opts);
     qemu_add_drive_opts(&qemu_legacy_drive_opts);
@@ -3313,6 +3315,10 @@ void qemu_init(int argc, char **argv, char **envp)
             case QEMU_OPTION_only_migratable:
                 only_migratable = 1;
                 break;
+            case QEMU_OPTION_cpr_enable:
+                cpr_modes |= BIT(qapi_enum_parse(&CprMode_lookup, optarg, -1,
+                                                 &error_fatal));
+                break;
             case QEMU_OPTION_nodefaults:
                 has_defaults = 0;
                 break;
@@ -3464,6 +3470,8 @@ void qemu_init(int argc, char **argv, char **envp)
     qemu_validate_options(machine_opts_dict);
     qemu_process_sugar_options();
 
+    cpr_init(cpr_modes);
+
     /*
      * These options affect everything else and should be processed
      * before daemonizing.
-- 
1.8.3.1