[PATCH V1 26/26] migration: only-migratable-modes

[Steve Sistare <steven.sistare@oracle.com>]

Add the only-migratable-modes option as a generalization of only-migratable.
Only devices that support all requested modes are allowed.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 include/migration/misc.h       |  3 +++
 include/sysemu/sysemu.h        |  1 -
 migration/migration-hmp-cmds.c | 26 +++++++++++++++++++++++++-
 migration/migration.c          | 22 +++++++++++++++++-----
 migration/savevm.c             |  2 +-
 qemu-options.hx                | 16 ++++++++++++++--
 system/globals.c               |  1 -
 system/vl.c                    | 13 ++++++++++++-
 target/s390x/cpu_models.c      |  4 +++-
 9 files changed, 75 insertions(+), 13 deletions(-)

diff --git a/include/migration/misc.h b/include/migration/misc.h
index 5b963ba..3ad2cd9 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -119,6 +119,9 @@ bool migration_incoming_postcopy_advised(void);
 /* True if background snapshot is active */
 bool migration_in_bg_snapshot(void);
 
+void migration_set_required_mode(MigMode mode);
+bool migration_mode_required(MigMode mode);
+
 /* migration/block-dirty-bitmap.c */
 void dirty_bitmap_mig_init(void);
 
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 5b4397e..0a9c4b4 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -8,7 +8,6 @@
 
 /* vl.c */
 
-extern int only_migratable;
 extern const char *qemu_name;
 extern QemuUUID qemu_uuid;
 extern bool qemu_uuid_set;
diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index 414c7e8..ca913b7 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -16,6 +16,7 @@
 #include "qemu/osdep.h"
 #include "block/qapi.h"
 #include "migration/snapshot.h"
+#include "migration/misc.h"
 #include "monitor/hmp.h"
 #include "monitor/monitor.h"
 #include "qapi/error.h"
@@ -33,6 +34,28 @@
 #include "options.h"
 #include "migration.h"
 
+static void migration_dump_modes(Monitor *mon)
+{
+    int mode, n = 0;
+
+    monitor_printf(mon, "only-migratable-modes: ");
+
+    for (mode = 0; mode < MIG_MODE__MAX; mode++) {
+        if (migration_mode_required(mode)) {
+            if (n++) {
+                monitor_printf(mon, ",");
+            }
+            monitor_printf(mon, "%s", MigMode_str(mode));
+        }
+    }
+
+    if (!n) {
+        monitor_printf(mon, "none\n");
+    } else {
+        monitor_printf(mon, "\n");
+    }
+}
+
 static void migration_global_dump(Monitor *mon)
 {
     MigrationState *ms = migrate_get_current();
@@ -41,7 +64,7 @@ static void migration_global_dump(Monitor *mon)
     monitor_printf(mon, "store-global-state: %s\n",
                    ms->store_global_state ? "on" : "off");
     monitor_printf(mon, "only-migratable: %s\n",
-                   only_migratable ? "on" : "off");
+                   migration_mode_required(MIG_MODE_NORMAL) ? "on" : "off");
     monitor_printf(mon, "send-configuration: %s\n",
                    ms->send_configuration ? "on" : "off");
     monitor_printf(mon, "send-section-footer: %s\n",
@@ -50,6 +73,7 @@ static void migration_global_dump(Monitor *mon)
                    ms->decompress_error_check ? "on" : "off");
     monitor_printf(mon, "clear-bitmap-shift: %u\n",
                    ms->clear_bitmap_shift);
+    migration_dump_modes(mon);
 }
 
 void hmp_info_migrate(Monitor *mon, const QDict *qdict)
diff --git a/migration/migration.c b/migration/migration.c
index 4984dee..5535b84 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1719,17 +1719,29 @@ static bool is_busy(Error **reasonp, Error **errp)
     return false;
 }
 
-static bool is_only_migratable(Error **reasonp, Error **errp, int modes)
+static int migration_modes_required;
+
+void migration_set_required_mode(MigMode mode)
+{
+    migration_modes_required |= BIT(mode);
+}
+
+bool migration_mode_required(MigMode mode)
+{
+    return !!(migration_modes_required & BIT(mode));
+}
+
+static bool modes_are_required(Error **reasonp, Error **errp, int modes)
 {
     ERRP_GUARD();
 
-    if (only_migratable && (modes & BIT(MIG_MODE_NORMAL))) {
+    if (migration_modes_required & modes) {
         error_propagate_prepend(errp, *reasonp,
-                                "disallowing migration blocker "
-                                "(--only-migratable) for: ");
+                                "-only-migratable{-modes}  specified, but: ");
         *reasonp = NULL;
         return true;
     }
+
     return false;
 }
 
@@ -1783,7 +1795,7 @@ int migrate_add_blocker_modes(Error **reasonp, Error **errp, MigMode mode, ...)
     modes = get_modes(mode, ap);
     va_end(ap);
 
-    if (is_only_migratable(reasonp, errp, modes)) {
+    if (modes_are_required(reasonp, errp, modes)) {
         return -EACCES;
     } else if (is_busy(reasonp, errp)) {
         return -EBUSY;
diff --git a/migration/savevm.c b/migration/savevm.c
index 6087c3a..e53ac84 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -3585,7 +3585,7 @@ void vmstate_register_ram_global(MemoryRegion *mr)
 bool vmstate_check_only_migratable(const VMStateDescription *vmsd)
 {
     /* check needed if --only-migratable is specified */
-    if (!only_migratable) {
+    if (!migration_mode_required(MIG_MODE_NORMAL)) {
         return true;
     }
 
diff --git a/qemu-options.hx b/qemu-options.hx
index f0dfda5..946d731 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4807,8 +4807,20 @@ DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \
     "-only-migratable     allow only migratable devices\n", QEMU_ARCH_ALL)
 SRST
 ``-only-migratable``
-    Only allow migratable devices. Devices will not be allowed to enter
-    an unmigratable state.
+    Only allow devices that can migrate using normal mode. Devices will not
+    be allowed to enter an unmigratable state.
+ERST
+
+DEF("only-migratable-modes", HAS_ARG, QEMU_OPTION_only_migratable_modes, \
+    "-only-migratable-modes mode1[,...]\n"
+    "                allow only devices that are migratable using mode(s)\n",
+    QEMU_ARCH_ALL)
+SRST
+``-only-migratable-modes mode1[,...]``
+    Only allow devices which are migratable using all modes in the list,
+    which guarantees that migration will not fail due to a blocker.
+    If both only-migratable-modes and only-migratable are specified,
+    or are specified multiple times, then the required modes accumulate.
 ERST
 
 DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
diff --git a/system/globals.c b/system/globals.c
index e353584..fdc263e 100644
--- a/system/globals.c
+++ b/system/globals.c
@@ -48,7 +48,6 @@ const char *qemu_name;
 unsigned int nb_prom_envs;
 const char *prom_envs[MAX_PROM_ENVS];
 uint8_t *boot_splash_filedata;
-int only_migratable; /* turn it off unless user states otherwise */
 int icount_align_option;
 
 /* The bytes in qemu_uuid are in the order specified by RFC4122, _not_ in the
diff --git a/system/vl.c b/system/vl.c
index b76881e..7e73be9 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -3458,7 +3458,18 @@ void qemu_init(int argc, char **argv)
                 incoming = optarg;
                 break;
             case QEMU_OPTION_only_migratable:
-                only_migratable = 1;
+                migration_set_required_mode(MIG_MODE_NORMAL);
+                break;
+            case QEMU_OPTION_only_migratable_modes:
+                {
+                    int i, mode;
+                    g_autofree char **words = g_strsplit(optarg, ",", -1);
+                    for (i = 0; words[i]; i++) {
+                        mode = qapi_enum_parse(&MigMode_lookup, words[i], -1,
+                                               &error_fatal);
+                        migration_set_required_mode(mode);
+                    }
+                }
                 break;
             case QEMU_OPTION_nodefaults:
                 has_defaults = 0;
diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
index 8ed3bb6..42ad160 100644
--- a/target/s390x/cpu_models.c
+++ b/target/s390x/cpu_models.c
@@ -16,6 +16,7 @@
 #include "kvm/kvm_s390x.h"
 #include "sysemu/kvm.h"
 #include "sysemu/tcg.h"
+#include "migration/misc.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "qapi/visitor.h"
@@ -526,7 +527,8 @@ static void check_compatibility(const S390CPUModel *max_model,
     }
 
 #ifndef CONFIG_USER_ONLY
-    if (only_migratable && test_bit(S390_FEAT_UNPACK, model->features)) {
+    if (migration_mode_required(MIG_MODE_NORMAL) &&
+        test_bit(S390_FEAT_UNPACK, model->features)) {
         error_setg(errp, "The unpack facility is not compatible with "
                    "the --only-migratable option. You must remove either "
                    "the 'unpack' facility or the --only-migratable option");
-- 
1.8.3.1