migration: introduce decompress-error-check

QEMU 3.0 enables strict check for compression & decompression to
make the migration more robust, that depends on the source to fix
the internal design which triggers the unexpected error conditions

To make it work for migrating old version QEMU to 2.13 QEMU, we
introduce this parameter to disable the error check on the
destination which is the default behavior of the machine type
which is older than 2.13, alternately, the strict check can be
enabled explicitly as followings:
      -M pc-q35-2.11 -global migration.decompress-error-check=true

Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

hw/arm/virt.c

@@ -1693,6 +1693,9 @@ static void machvirt_machine_init(void)
 }
 type_init(machvirt_machine_init);
 
+#define VIRT_COMPAT_2_12 \
+    HW_COMPAT_2_12
+
 static void virt_2_12_instance_init(Object *obj)
 {
     VirtMachineState *vms = VIRT_MACHINE(obj);
@@ -1763,6 +1766,7 @@ static void virt_2_12_instance_init(Object *obj)
 
 static void virt_machine_2_12_options(MachineClass *mc)
 {
+    SET_MACHINE_COMPAT(mc, VIRT_COMPAT_2_12);
 }
 DEFINE_VIRT_MACHINE_AS_LATEST(2, 12)
 

hw/i386/pc_piix.c

@@ -430,6 +430,7 @@ static void pc_i440fx_3_0_machine_options(MachineClass *m)
     pc_i440fx_machine_options(m);
     m->alias = "pc";
     m->is_default = 1;
+    SET_MACHINE_COMPAT(m, PC_COMPAT_2_12);
 }
 
 DEFINE_I440FX_MACHINE(v3_0, "pc-i440fx-3.0", NULL,

hw/i386/pc_q35.c

@@ -312,6 +312,7 @@ static void pc_q35_3_0_machine_options(MachineClass *m)
 {
     pc_q35_machine_options(m);
     m->alias = "q35";
+    SET_MACHINE_COMPAT(m, PC_COMPAT_2_12);
 }
 
 DEFINE_Q35_MACHINE(v3_0, "pc-q35-3.0", NULL,

include/hw/compat.h

@@ -1,7 +1,12 @@
 #ifndef HW_COMPAT_H
 #define HW_COMPAT_H
 
-#define HW_COMPAT_2_12
+#define HW_COMPAT_2_12 \
+    {\
+        .driver   = "migration",\
+        .property = "decompress-error-check",\
+        .value    = "off",\
+    },
 
 #define HW_COMPAT_2_11 \
     {\

migration/migration.c

@@ -2971,6 +2971,8 @@ void migration_global_dump(Monitor *mon)
                    ms->send_configuration ? "on" : "off");
     monitor_printf(mon, "send-section-footer: %s\n",
                    ms->send_section_footer ? "on" : "off");
+    monitor_printf(mon, "decompress-error-check: %s\n",
+                   ms->decompress_error_check ? "on" : "off");
 }
 
 #define DEFINE_PROP_MIG_CAP(name, x)             \
@@ -2984,6 +2986,8 @@ static Property migration_properties[] = {
                      send_configuration, true),
     DEFINE_PROP_BOOL("send-section-footer", MigrationState,
                      send_section_footer, true),
+    DEFINE_PROP_BOOL("decompress-error-check", MigrationState,
+                      decompress_error_check, true),
 
     /* Migration parameters */
     DEFINE_PROP_UINT8("x-compress-level", MigrationState,

migration/migration.h

@@ -212,6 +212,13 @@ struct MigrationState
     /* Needed by postcopy-pause state */
     QemuSemaphore postcopy_pause_sem;
     QemuSemaphore postcopy_pause_rp_sem;
+    /*
+     * Whether we abort the migration if decompression errors are
+     * detected at the destination. It is left at false for qemu
+     * older than 3.0, since only newer qemu sends streams that
+     * do not trigger spurious decompression errors.
+     */
+    bool decompress_error_check;
 };
 
 void migrate_set_state(int *state, int old_state, int new_state);

migration/ram.c

@@ -2881,7 +2881,7 @@ static void *do_data_decompress(void *opaque)
 
             ret = qemu_uncompress_data(&param->stream, des, pagesize,
                                        param->compbuf, len);
-            if (ret < 0) {
+            if (ret < 0 && migrate_get_current()->decompress_error_check) {
                 error_report("decompress data failed");
                 qemu_file_set_error(decomp_file, ret);
             }