images/inventory: add fields for plugins

This patch extends the inventory image with a new "plugins" entry that
contains *optional* boolean flags for the AMDGPU and CUDA plugins.

These fields are set when a plugin is initialized, and their values
indicate whether the checkpoint contains GPU state. In other words,
a missing field indicates that the plugin was not initialized during
checkpoint.

During restore, these fields are used to avoid loading unnecessary
plugins or to show an appropriate error message if a required plugin
is missing. If the "plugins" entry is not present in the inventory
image, all CRIU plugins are loaded to preserve backwards compatibility.

It is important to note that these fields are set to `true` only when
the checkpoint contains GPU state. This approach allows to migrate
processes (or containers) from a GPU-enabled system to a system without
a GPU, when the GPU is not utilized.

Examples:

1. The checkpoint was created without any CRIU plugins:
{
    "magic": "INVENTORY",
    "entries": [
	{
	    "plugins": {}
	}
    ]
}

2. The checkpoint was created with both AMD GPU and CUDA plugins
   installed but does not contain GPU state:

{
    "magic": "INVENTORY",
    "entries": [
        {
            "plugins": {
                "amdgpu": false,
                "cuda": false
            }
        }
    ]
}

3. The checkpoint was created with only with the CUDA plugin installed
   and contains GPU state:
{
    "magic": "INVENTORY",
    "entries": [
        {
            "plugins": {
                "cuda": true
            }
        }
    ]
}

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

criu/cr-restore.c

@@ -2353,12 +2353,12 @@ int cr_restore_tasks(void)
 	if (init_service_fd())
 		return 1;
 
-	if (cr_plugin_init(CR_PLUGIN_STAGE__RESTORE))
-		return -1;
-
 	if (check_img_inventory(/* restore = */ true) < 0)
 		goto err;
 
+	if (cr_plugin_init(CR_PLUGIN_STAGE__RESTORE))
+		return -1;
+
 	if (init_stats(RESTORE_STATS))
 		goto err;
 

criu/image.c

@@ -26,6 +26,39 @@ TaskKobjIdsEntry *root_ids;
 u32 root_cg_set;
 Lsmtype image_lsm;
 
+static PluginsEntry criu_plugins = PLUGINS_ENTRY__INIT;
+bool enabled_plugins_inventory;
+
+void __attribute__((used)) set_cuda_plugin(void)
+{
+	criu_plugins.has_cuda = true;
+}
+
+void __attribute__((used)) set_cuda_plugin_enabled(void)
+{
+	criu_plugins.cuda = true;
+}
+
+bool __attribute__((used)) get_cuda_plugin_enabled(void)
+{
+	return criu_plugins.has_cuda && criu_plugins.cuda;
+}
+
+void __attribute__((used)) set_amdgpu_plugin(void)
+{
+	criu_plugins.has_amdgpu = true;
+}
+
+void __attribute__((used)) set_amdgpu_plugin_enabled(void)
+{
+	criu_plugins.amdgpu = true;
+}
+
+bool __attribute__((used)) get_amdgpu_plugin_enabled(void)
+{
+	return criu_plugins.has_amdgpu && criu_plugins.amdgpu;
+}
+
 int check_img_inventory(bool restore)
 {
 	int ret = -1;
@@ -99,6 +132,16 @@ int check_img_inventory(bool restore)
 		} else {
 			opts.network_lock_method = he->network_lock_method;
 		}
+
+		if (he->plugins == NULL) {
+			enabled_plugins_inventory = false;
+		} else {
+			criu_plugins.has_amdgpu = he->plugins->has_amdgpu;
+			criu_plugins.amdgpu = he->plugins->amdgpu;
+			criu_plugins.has_cuda = he->plugins->has_cuda;
+			criu_plugins.cuda = he->plugins->cuda;
+			enabled_plugins_inventory = true;
+		}
 	}
 
 	ret = 0;
@@ -121,6 +164,7 @@ int write_img_inventory(InventoryEntry *he)
 	if (!img)
 		return -1;
 
+	he->plugins = &criu_plugins;
 	ret = pb_write_one(img, he, PB_INVENTORY);
 
 	xfree(he->root_ids);

criu/include/image.h

@@ -177,4 +177,17 @@ extern int read_img_str(struct cr_img *, char **pstr, int size);
 
 extern void close_image(struct cr_img *);
 
+/* For backwards compatibility, if the inventory image does not contain
+ * a "plugins" field, we should load all plugins. */
+extern bool enabled_plugins_inventory;
+
+extern void set_cuda_plugin(void);
+extern void set_cuda_plugin_enabled(void);
+extern bool get_cuda_plugin_enabled(void);
+
+extern void set_amdgpu_plugin(void);
+extern void set_amdgpu_plugin_enabled(void);
+extern bool get_amdgpu_plugin_enabled(void);
+
+
 #endif /* __CR_IMAGE_H__ */

criu/plugin.c

@@ -205,6 +205,10 @@ int cr_plugin_init(int stage)
 	char *path;
 	size_t i;
 	DIR *d;
+	bool cuda_plugin_required = get_cuda_plugin_enabled();
+	bool cuda_plugin_loaded = false;
+	bool amdgpu_plugin_required = get_amdgpu_plugin_enabled();
+	bool amdgpu_plugin_loaded = false;
 
 	INIT_LIST_HEAD(&cr_plugin_ctl.head);
 	for (i = 0; i < ARRAY_SIZE(cr_plugin_ctl.hook_chain); i++)
@@ -247,6 +251,18 @@ int cr_plugin_init(int stage)
 		if (len < 3 || strncmp(de->d_name + len - 3, ".so", 3))
 			continue;
 
+		if (enabled_plugins_inventory && stage == CR_PLUGIN_STAGE__RESTORE) {
+			if (len == 16 && strncmp(de->d_name, "amdgpu_plugin.so", 16)) {
+				if (amdgpu_plugin_required == false)
+					continue; /* Skip unnecessary plugin */
+				amdgpu_plugin_loaded = true;
+			} else if (len == 14 && strncmp(de->d_name, "cuda_plugin.so", 14)) {
+				if (cuda_plugin_required == false)
+					continue; /* Skip unnecessary plugin */
+				cuda_plugin_loaded = true;
+			}
+		}
+
 		if (snprintf(path, sizeof(path), "%s/%s", opts.libdir, de->d_name) >= sizeof(path)) {
 			pr_err("Unable to build plugin path\n");
 			goto err;
@@ -256,6 +272,18 @@ int cr_plugin_init(int stage)
 			goto err;
 	}
 
+	if (enabled_plugins_inventory && stage == CR_PLUGIN_STAGE__RESTORE) {
+		if (amdgpu_plugin_required && !amdgpu_plugin_loaded) {
+			pr_err("AMD GPU plugin is required for restore\n");
+			goto err;
+		}
+
+		if (cuda_plugin_required && !cuda_plugin_loaded) {
+			pr_err("CUDA plugin is required for restore\n");
+			goto err;
+		}
+	}
+
 	exit_code = 0;
 err:
 	closedir(d);

images/inventory.proto

@@ -10,6 +10,11 @@ enum lsmtype {
 	APPARMOR	= 2;
 }
 
+message plugins_entry {
+	optional bool amdgpu = 1;
+	optional bool cuda = 2;
+};
+
 message inventory_entry {
 	required uint32			img_version	= 1;
 	optional bool			fdinfo_per_id	= 2;
@@ -21,4 +26,5 @@ message inventory_entry {
 	optional uint32			pre_dump_mode	= 9;
 	optional bool			tcp_close	= 10;
 	optional uint32			network_lock_method	= 11;
+	optional plugins_entry		plugins = 12;
 }

plugins/amdgpu/amdgpu_plugin.c

@@ -360,6 +360,8 @@ int amdgpu_plugin_init(int stage)
 	kfd_max_buffer_size = 0;
 	getenv_size_t("KFD_MAX_BUFFER_SIZE", &kfd_max_buffer_size);
 
+	set_amdgpu_plugin();
+
 	return 0;
 }
 
@@ -414,6 +416,10 @@ int amdgpu_plugin_handle_device_vma(int fd, const struct stat *st_buf)
 	if (ret)
 		pr_perror("%s(), Can't handle VMAs of input device", __func__);
 
+	/* Set the AMD GPU plugin as enabled in the inventory image
+         * only if the checkpoint contains GPU state (i.e., ret == 0). */
+	set_amdgpu_plugin_enabled();
+
 	return ret;
 }
 CR_PLUGIN_REGISTER_HOOK(CR_PLUGIN_HOOK__HANDLE_DEVICE_VMA, amdgpu_plugin_handle_device_vma)

plugins/cuda/cuda_plugin.c

@@ -334,6 +334,10 @@ int cuda_plugin_checkpoint_devices(int pid)
 		return 0;
 	}
 
+	/* Set the CUDA plugin as enabled in the inventory image
+	 * only if the checkpoint contains GPU state (i.e., restore_tid != -1). */
+	set_cuda_plugin_enabled();
+
 	pr_info("Checkpointing CUDA devices on pid %d restore_tid %d\n", pid, restore_tid);
 	/* We need to resume the checkpoint thread to prepare the mappings for
 	 * checkpointing
@@ -463,6 +467,8 @@ int cuda_plugin_init(int stage)
 {
 	int ret;
 
+	set_cuda_plugin();
+
 	if (!fault_injected(FI_PLUGIN_CUDA_FORCE_ENABLE) && access("/dev/nvidiactl", F_OK)) {
 		pr_info("/dev/nvidiactl doesn't exist. The CUDA plugin is disabled.\n");
 		plugin_disabled = true;