[PATCH V8 37/39] cpr: only-cpr-capable option

[Steve Sistare]

Add the only-cpr-capable option, which causes qemu to exit with an error
if any devices that are not capable of cpr are added.  This guarantees that
cpr-save will not fail due to a blocker.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 include/migration/cpr.h |  2 +-
 migration/cpr.c         | 13 +++++++++++--
 qemu-options.hx         |  8 ++++++++
 softmmu/vl.c            |  6 +++++-
 4 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/include/migration/cpr.h b/include/migration/cpr.h
index ab5f53e..c7eb914 100644
--- a/include/migration/cpr.h
+++ b/include/migration/cpr.h
@@ -11,7 +11,7 @@
 #include "qapi/qapi-types-cpr.h"
 #include "qemu/notify.h"
 
-void cpr_init(int modes);
+void cpr_init(int modes, bool only_cpr_capable);
 void cpr_set_mode(CprMode mode);
 CprMode cpr_get_mode(void);
 bool cpr_enabled(CprMode mode);
diff --git a/migration/cpr.c b/migration/cpr.c
index 9d6bca4..7f507f1 100644
--- a/migration/cpr.c
+++ b/migration/cpr.c
@@ -18,9 +18,11 @@
 #include "sysemu/sysemu.h"
 
 static int cpr_enabled_modes;
+static bool only_cpr_capable;
 
-void cpr_init(int modes)
+void cpr_init(int modes, bool only_cpr)
 {
+    only_cpr_capable = only_cpr;
     cpr_enabled_modes = modes;
     cpr_state_load(&error_fatal);
 }
@@ -36,7 +38,7 @@ static GSList *cpr_blockers[CPR_MODE__MAX];
  * Add blocker for each mode in varargs list, or for all modes if CPR_MODE_ALL
  * is specified.  Caller terminates the list with 0 or CPR_MODE_ALL.  This
  * function takes ownership of *reasonp, and frees it on error, or in
- * cpr_del_blocker.  errp is set in a later patch.
+ * cpr_del_blocker.
  */
 int cpr_add_blocker(Error **reasonp, Error **errp, CprMode mode, ...)
 {
@@ -55,6 +57,13 @@ int cpr_add_blocker(Error **reasonp, Error **errp, CprMode 
mode, ...)
         modes = BIT(CPR_MODE__MAX) - 1;
     }
 
+    if (only_cpr_capable && (cpr_enabled_modes & modes)) {
+        error_propagate_prepend(errp, *reasonp,
+                                "-only-cpr-capable specified, but: ");
+        *reasonp = NULL;
+        return -EACCES;
+    }
+
     for (mode = 0; mode < CPR_MODE__MAX; mode++) {
         if (modes & BIT(mode)) {
             cpr_blockers[mode] = g_slist_prepend(cpr_blockers[mode], *reasonp);
diff --git a/qemu-options.hx b/qemu-options.hx
index 2f4bb2b..25e392f 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4511,6 +4511,14 @@ SRST
     commands.
 ERST
 
+DEF("only-cpr-capable", 0, QEMU_OPTION_only_cpr_capable, \
+    "-only-cpr-capable    allow only cpr capable devices\n", QEMU_ARCH_ALL)
+SRST
+``-only-cpr-capable``
+    Only allow cpr capable devices, which guarantees that cpr-save will not
+    fail due to a cpr blocker.
+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 3e19c74..1bee692 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -2604,6 +2604,7 @@ void qemu_init(int argc, char **argv, char **envp)
     bool userconfig = true;
     FILE *vmstate_dump_file = NULL;
     int cpr_modes = 0;
+    bool only_cpr_capable = false;
 
     qemu_add_opts(&qemu_drive_opts);
     qemu_add_drive_opts(&qemu_legacy_drive_opts);
@@ -3321,6 +3322,9 @@ void qemu_init(int argc, char **argv, char **envp)
                 cpr_modes |= BIT(qapi_enum_parse(&CprMode_lookup, optarg, -1,
                                                  &error_fatal));
                 break;
+            case QEMU_OPTION_only_cpr_capable:
+                only_cpr_capable = true;
+                break;
             case QEMU_OPTION_nodefaults:
                 has_defaults = 0;
                 break;
@@ -3472,7 +3476,7 @@ void qemu_init(int argc, char **argv, char **envp)
     qemu_validate_options(machine_opts_dict);
     qemu_process_sugar_options();
 
-    cpr_init(cpr_modes);
+    cpr_init(cpr_modes, only_cpr_capable);
 
     /*
      * These options affect everything else and should be processed
-- 
1.8.3.1