RR Upgrade (#1267)

* added replay check to loadvm

* changed the PANDA_IS_IN_REPLAY flag to be a global var

* made it so that loadvm ALWAYS excludes non-essential devices

* exclude unnecessary devices from snapshots while recording

* cpu_common is not important for replays

* minor tweaks and cleanup

* more minor cleanup

* forgot to commit the header sooner oops

* reset the rr debugging code

* removed section ID checks on snapshot load

* reset rr debug code

* setting panda_is_in_record inside of scissors

* wrapped global flag setting/unsetting in shim functions

include/migration/savevm.h

@@ -0,0 +1,4 @@
+extern int panda_is_in_record;
+
+void set_rr_snapshot(void);
+void unset_rr_snapshot(void);

migration/savevm.c

@@ -55,6 +55,7 @@
 #include "io/channel-buffer.h"
 #include "io/channel-file.h"
 #include "panda/callbacks/cb-support.h"
+#include "migration/savevm.h"
 
 #ifndef ETH_P_RARP
 #define ETH_P_RARP 0x8035
@@ -83,6 +84,30 @@ static struct mig_cmd_args {
     [MIG_CMD_MAX]              = { .len = -1, .name = "MAX" },
 };
 
+const char* important_idstrs[] = {
+"ram",
+"cpu",
+NULL
+};
+
+int idstr_is_important(char* idstr);
+
+
+int idstr_is_important(char* idstr) {
+
+    int i = 0;
+    while (important_idstrs[i]) {
+        if (strcmp(idstr, important_idstrs[i]) == 0) {
+            return 1;
+        }
+
+        i++;
+    }
+
+    return 0;
+}
+
+
 static int announce_self_create(uint8_t *buf,
                                 uint8_t *mac_addr)
 {
@@ -1153,6 +1178,10 @@ void qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only)
     json_start_array(vmdesc, "devices");
     QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
 
+        if (panda_is_in_record && !idstr_is_important(se->idstr)) {
+            continue;
+        }
+
         if ((!se->ops || !se->ops->save_state) && !se->vmsd) {
             continue;
         }
@@ -1838,6 +1867,7 @@ void loadvm_free_handlers(MigrationIncomingState *mis)
     }
 }
 
+
 static int
 qemu_loadvm_section_start_full(QEMUFile *f, MigrationIncomingState *mis)
 {
@@ -1859,6 +1889,7 @@ qemu_loadvm_section_start_full(QEMUFile *f, MigrationIncomingState *mis)
 
     trace_qemu_loadvm_state_section_startfull(section_id, idstr,
             instance_id, version_id);
+
     /* Find savevm section */
     se = find_se(idstr, instance_id);
     if (se == NULL) {

panda/plugins/scissors/scissors.c

@@ -18,6 +18,7 @@
 #include "panda/include/panda/rr/panda_rr2.h"
 
 #include "migration/migration.h"
+#include "migration/savevm.h"
 #include "include/exec/address-spaces.h"
 #include "migration/qemu-file.h"
 #include "io/channel-file.h"
@@ -256,8 +257,13 @@ static inline void save_snp_shot(void) {
     QIOChannelFile* ioc =
         qio_channel_file_new_path(snp_name, O_WRONLY | O_CREAT, 0660, NULL);
     QEMUFile* snp = qemu_fopen_channel_output(QIO_CHANNEL(ioc));
+
+    set_rr_snapshot();
+
     qemu_savevm_state(snp, NULL);
     qemu_fclose(snp);
+
+    unset_rr_snapshot();
 }
 
 static void create_command_file(void) {

panda/src/rr/rr_log.c

@@ -57,6 +57,7 @@
 #include "panda/callbacks/cb-support.h"
 #include "exec/gdbstub.h"
 #include "sysemu/cpus.h"
+#include "migration/savevm.h"
 
 //#define RR_DEBUG
 
@@ -89,6 +90,16 @@ struct rr_file_info*  recording_info = NULL;
 
 bool rr_replay_complete = false;
 
+int panda_is_in_record = 0;
+
+void set_rr_snapshot(void) {
+    panda_is_in_record = 1;
+}
+
+void unset_rr_snapshot(void) {
+    panda_is_in_record = 0;
+}
+
 // our own assertion mechanism
 #define rr_assert(exp)                                                         \
     if (!(exp)) {                                                              \
@@ -1583,6 +1594,9 @@ int rr_do_begin_record(const char* file_name_full, CPUState* cpu_state)
     QIOChannelFile* ioc =
         qio_channel_file_new_path(name_buf, O_WRONLY | O_CREAT, 0660, NULL);
     QEMUFile* snp = qemu_fopen_channel_output(QIO_CHANNEL(ioc));
+
+    set_rr_snapshot();
+
     snapshot_ret = qemu_savevm_state(snp, &err);
     qemu_fclose(snp);
     // log_all_cpu_states();
@@ -1643,6 +1657,8 @@ void rr_do_end_record(void)
 
     printf("...complete!\n");
 
+    unset_rr_snapshot();
+
     // log_all_cpu_states();
 
     rr_destroy_log();