migration-test: memory_backend

Allow each migration test to define its own memory backend, replacing
the standard "-m <size>" specification.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/1736967650-129648-18-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>

tests/qtest/migration/framework.c

@@ -221,6 +221,7 @@ int migrate_start(QTestState **from, QTestState **to, const char *uri,
     g_autofree char *machine = NULL;
     const char *bootpath;
     g_autoptr(QList) capabilities = migrate_start_get_qmp_capabilities(args);
+    g_autofree char *memory_backend = NULL;
 
     if (args->use_shmem) {
         if (!g_file_test("/dev/shm", G_FILE_TEST_IS_DIR)) {
@@ -296,6 +297,12 @@ int migrate_start(QTestState **from, QTestState **to, const char *uri,
             memory_size, shmem_path);
     }
 
+    if (args->memory_backend) {
+        memory_backend = g_strdup_printf(args->memory_backend, memory_size);
+    } else {
+        memory_backend = g_strdup_printf("-m %s ", memory_size);
+    }
+
     if (args->use_dirty_ring) {
         kvm_opts = ",dirty-ring-size=4096";
     }
@@ -314,12 +321,12 @@ int migrate_start(QTestState **from, QTestState **to, const char *uri,
     cmd_source = g_strdup_printf("-accel kvm%s -accel tcg "
                                  "-machine %s,%s "
                                  "-name source,debug-threads=on "
-                                 "-m %s "
+                                 "%s "
                                  "-serial file:%s/src_serial "
                                  "%s %s %s %s",
                                  kvm_opts ? kvm_opts : "",
                                  machine, machine_opts,
-                                 memory_size, tmpfs,
+                                 memory_backend, tmpfs,
                                  arch_opts ? arch_opts : "",
                                  shmem_opts ? shmem_opts : "",
                                  args->opts_source ? args->opts_source : "",
@@ -335,13 +342,13 @@ int migrate_start(QTestState **from, QTestState **to, const char *uri,
     cmd_target = g_strdup_printf("-accel kvm%s -accel tcg "
                                  "-machine %s,%s "
                                  "-name target,debug-threads=on "
-                                 "-m %s "
+                                 "%s "
                                  "-serial file:%s/dest_serial "
                                  "-incoming %s "
                                  "%s %s %s %s",
                                  kvm_opts ? kvm_opts : "",
                                  machine, machine_opts,
-                                 memory_size, tmpfs, uri,
+                                 memory_backend, tmpfs, uri,
                                  arch_opts ? arch_opts : "",
                                  shmem_opts ? shmem_opts : "",
                                  args->opts_target ? args->opts_target : "",

tests/qtest/migration/framework.h

@@ -111,6 +111,11 @@ typedef struct {
     bool suspend_me;
     /* enable OOB QMP capability */
     bool oob;
+    /*
+     * Format string for the main memory backend, containing one %s where the
+     * size is plugged in.  If omitted, "-m %s" is used.
+     */
+    const char *memory_backend;
 } MigrateStart;
 
 typedef enum PostcopyRecoveryFailStage {