plugins/loader.c - qemu - Git at Google

 /*
  * QEMU Plugin Core Loader Code
  *
  * This is the code responsible for loading and unloading the plugins.
  * Aside from the basic housekeeping tasks we also need to ensure any
  * generated code is flushed when we remove a plugin so we cannot end
  * up calling and unloaded helper function.
  *
  * Copyright (C) 2017, Emilio G. Cota <cota@braap.org>
  * Copyright (C) 2019, Linaro
  *
  * License: GNU GPL, version 2 or later.
  *   See the COPYING file in the top-level directory.
  *
  * SPDX-License-Identifier: GPL-2.0-or-later
  */

 #include "qemu/osdep.h"
 #include "qemu/error-report.h"
 #include "qemu/config-file.h"
 #include "qemu/help_option.h"
 #include "qapi/error.h"
 #include "qemu/lockable.h"
 #include "qemu/option.h"
 #include "qemu/rcu_queue.h"
 #include "qemu/qht.h"
 #include "qemu/bitmap.h"
 #include "qemu/cacheinfo.h"
 #include "qemu/xxhash.h"
 #include "qemu/plugin.h"
 #include "qemu/memalign.h"
 #include "hw/core/cpu.h"
 #include "exec/tb-flush.h"
 #ifndef CONFIG_USER_ONLY
 #include "hw/boards.h"
 #endif

 #include "plugin.h"

 /*
  * For convenience we use a bitmap for plugin.mask, but really all we need is a
  * u32, which is what we store in TranslationBlock.
  */
 QEMU_BUILD_BUG_ON(QEMU_PLUGIN_EV_MAX > 32);

 struct qemu_plugin_desc {
     char *path;
     char **argv;
     QTAILQ_ENTRY(qemu_plugin_desc) entry;
     int argc;
 };

 struct qemu_plugin_parse_arg {
     QemuPluginList *head;
     struct qemu_plugin_desc *curr;
 };

 QemuOptsList qemu_plugin_opts = {
     .name = "plugin",
     .implied_opt_name = "file",
     .head = QTAILQ_HEAD_INITIALIZER(qemu_plugin_opts.head),
     .desc = {
         /* do our own parsing to support multiple plugins */
         { /* end of list */ }
     },
 };

 typedef int (*qemu_plugin_install_func_t)(qemu_plugin_id_t, const qemu_info_t *, int, char **);

 extern struct qemu_plugin_state plugin;

 void qemu_plugin_add_dyn_cb_arr(GArray *arr)
 {
     uint32_t hash = qemu_xxhash2((uint64_t)(uintptr_t)arr);
     bool inserted;

     inserted = qht_insert(&plugin.dyn_cb_arr_ht, arr, hash, NULL);
     g_assert(inserted);
 }

 static struct qemu_plugin_desc *plugin_find_desc(QemuPluginList *head,
                                                  const char *path)
 {
     struct qemu_plugin_desc *desc;

     QTAILQ_FOREACH(desc, head, entry) {
         if (strcmp(desc->path, path) == 0) {
             return desc;
         }
     }
     return NULL;
 }

 static int plugin_add(void *opaque, const char *name, const char *value,
                       Error **errp)
 {
     struct qemu_plugin_parse_arg *arg = opaque;
     struct qemu_plugin_desc *p;
     bool is_on;
     char *fullarg;

     if (is_help_option(value)) {
         printf("Plugin options\n");
         printf("  file=<path/to/plugin.so>\n");
         printf("  plugin specific arguments\n");
         exit(0);
     } else if (strcmp(name, "file") == 0) {
         if (strcmp(value, "") == 0) {
             error_setg(errp, "requires a non-empty argument");
             return 1;
         }
         p = plugin_find_desc(arg->head, value);
         if (p == NULL) {
             p = g_new0(struct qemu_plugin_desc, 1);
             p->path = g_strdup(value);
             QTAILQ_INSERT_TAIL(arg->head, p, entry);
         }
         arg->curr = p;
     } else {
         if (arg->curr == NULL) {
             error_setg(errp, "missing earlier '-plugin file=' option");
             return 1;
         }

         if (g_strcmp0(name, "arg") == 0 &&
                 !qapi_bool_parse(name, value, &is_on, NULL)) {
             if (strchr(value, '=') == NULL) {
                 /* Will treat arg="argname" as "argname=on" */
                 fullarg = g_strdup_printf("%s=%s", value, "on");
             } else {
                 fullarg = g_strdup_printf("%s", value);
             }
             warn_report("using 'arg=%s' is deprecated", value);
             error_printf("Please use '%s' directly\n", fullarg);
         } else {
             fullarg = g_strdup_printf("%s=%s", name, value);
         }

         p = arg->curr;
         p->argc++;
         p->argv = g_realloc_n(p->argv, p->argc, sizeof(char *));
         p->argv[p->argc - 1] = fullarg;
     }

     return 0;
 }

 void qemu_plugin_opt_parse(const char *optstr, QemuPluginList *head)
 {
     struct qemu_plugin_parse_arg arg;
     QemuOpts *opts;

     opts = qemu_opts_parse_noisily(qemu_find_opts("plugin"), optstr, true);
     if (opts == NULL) {
         exit(1);
     }
     arg.head = head;
     arg.curr = NULL;
     qemu_opt_foreach(opts, plugin_add, &arg, &error_fatal);
     qemu_opts_del(opts);
 }

 /*
  * From: https://en.wikipedia.org/wiki/Xorshift
  * This is faster than rand_r(), and gives us a wider range (RAND_MAX is only
  * guaranteed to be >= INT_MAX).
  */
 static uint64_t xorshift64star(uint64_t x)
 {
     x ^= x >> 12; /* a */
     x ^= x << 25; /* b */
     x ^= x >> 27; /* c */
     return x * UINT64_C(2685821657736338717);
 }

 /*
  * Disable CFI checks.
  * The install and version functions have been loaded from an external library
  * so we do not have type information
  */
 QEMU_DISABLE_CFI
 static int plugin_load(struct qemu_plugin_desc *desc, const qemu_info_t *info, Error **errp)
 {
     qemu_plugin_install_func_t install;
     struct qemu_plugin_ctx *ctx;
     gpointer sym;
     int rc;

     ctx = qemu_memalign(qemu_dcache_linesize, sizeof(*ctx));
     memset(ctx, 0, sizeof(*ctx));
     ctx->desc = desc;

     ctx->handle = g_module_open(desc->path, G_MODULE_BIND_LOCAL);
     if (ctx->handle == NULL) {
         error_setg(errp, "Could not load plugin %s: %s", desc->path, g_module_error());
         goto err_dlopen;
     }

     if (!g_module_symbol(ctx->handle, "qemu_plugin_install", &sym)) {
         error_setg(errp, "Could not load plugin %s: %s", desc->path, g_module_error());
         goto err_symbol;
     }
     install = (qemu_plugin_install_func_t) sym;
     /* symbol was found; it could be NULL though */
     if (install == NULL) {
         error_setg(errp, "Could not load plugin %s: qemu_plugin_install is NULL",
                    desc->path);
         goto err_symbol;
     }

     if (!g_module_symbol(ctx->handle, "qemu_plugin_version", &sym)) {
         error_setg(errp, "Could not load plugin %s: plugin does not declare API version %s",
                    desc->path, g_module_error());
         goto err_symbol;
     } else {
         int version = *(int *)sym;
         if (version < QEMU_PLUGIN_MIN_VERSION) {
             error_setg(errp, "Could not load plugin %s: plugin requires API version %d, but "
                        "this QEMU supports only a minimum version of %d",
                        desc->path, version, QEMU_PLUGIN_MIN_VERSION);
             goto err_symbol;
         } else if (version > QEMU_PLUGIN_VERSION) {
             error_setg(errp, "Could not load plugin %s: plugin requires API version %d, but "
                        "this QEMU supports only up to version %d",
                        desc->path, version, QEMU_PLUGIN_VERSION);
             goto err_symbol;
         }
     }

     qemu_rec_mutex_lock(&plugin.lock);

     /* find an unused random id with &ctx as the seed */
     ctx->id = (uint64_t)(uintptr_t)ctx;
     for (;;) {
         void *existing;

         ctx->id = xorshift64star(ctx->id);
         existing = g_hash_table_lookup(plugin.id_ht, &ctx->id);
         if (likely(existing == NULL)) {
             bool success;

             success = g_hash_table_insert(plugin.id_ht, &ctx->id, &ctx->id);
             g_assert(success);
             break;
         }
     }
     QTAILQ_INSERT_TAIL(&plugin.ctxs, ctx, entry);
     ctx->installing = true;
     rc = install(ctx->id, info, desc->argc, desc->argv);
     ctx->installing = false;
     if (rc) {
         error_setg(errp, "Could not load plugin %s: qemu_plugin_install returned error code %d",
                    desc->path, rc);
         /*
          * we cannot rely on the plugin doing its own cleanup, so
          * call a full uninstall if the plugin did not yet call it.
          */
         if (!ctx->uninstalling) {
             plugin_reset_uninstall(ctx->id, NULL, false);
         }
     }

     qemu_rec_mutex_unlock(&plugin.lock);
     return rc;

  err_symbol:
     g_module_close(ctx->handle);
  err_dlopen:
     qemu_vfree(ctx);
     return 1;
 }

 /* call after having removed @desc from the list */
 static void plugin_desc_free(struct qemu_plugin_desc *desc)
 {
     int i;

     for (i = 0; i < desc->argc; i++) {
         g_free(desc->argv[i]);
     }
     g_free(desc->argv);
     g_free(desc->path);
     g_free(desc);
 }

 /**
  * qemu_plugin_load_list - load a list of plugins
  * @head: head of the list of descriptors of the plugins to be loaded
  *
  * Returns 0 if all plugins in the list are installed, !0 otherwise.
  *
  * Note: the descriptor of each successfully installed plugin is removed
  * from the list given by @head.
  */
 int qemu_plugin_load_list(QemuPluginList *head, Error **errp)
 {
     struct qemu_plugin_desc *desc, *next;
     g_autofree qemu_info_t *info = g_new0(qemu_info_t, 1);

     info->target_name = TARGET_NAME;
     info->version.min = QEMU_PLUGIN_MIN_VERSION;
     info->version.cur = QEMU_PLUGIN_VERSION;
 #ifndef CONFIG_USER_ONLY
     MachineState *ms = MACHINE(qdev_get_machine());
     info->system_emulation = true;
     info->system.smp_vcpus = ms->smp.cpus;
     info->system.max_vcpus = ms->smp.max_cpus;
 #else
     info->system_emulation = false;
 #endif

     QTAILQ_FOREACH_SAFE(desc, head, entry, next) {
         int err;

         err = plugin_load(desc, info, errp);
         if (err) {
             return err;
         }
         QTAILQ_REMOVE(head, desc, entry);
     }
     return 0;
 }

 struct qemu_plugin_reset_data {
     struct qemu_plugin_ctx *ctx;
     qemu_plugin_simple_cb_t cb;
     bool reset;
 };

 static void plugin_reset_destroy__locked(struct qemu_plugin_reset_data *data)
 {
     struct qemu_plugin_ctx *ctx = data->ctx;
     enum qemu_plugin_event ev;
     bool success;

     /*
      * After updating the subscription lists there is no need to wait for an RCU
      * grace period to elapse, because right now we either are in a "safe async"
      * work environment (i.e. all vCPUs are asleep), or no vCPUs have yet been
      * created.
      */
     for (ev = 0; ev < QEMU_PLUGIN_EV_MAX; ev++) {
         plugin_unregister_cb__locked(ctx, ev);
     }

     if (data->reset) {
         g_assert(ctx->resetting);
         if (data->cb) {
             data->cb(ctx->id);
         }
         ctx->resetting = false;
         g_free(data);
         return;
     }

     g_assert(ctx->uninstalling);
     /* we cannot dlclose if we are going to return to plugin code */
     if (ctx->installing) {
         error_report("Calling qemu_plugin_uninstall from the install function "
                      "is a bug. Instead, return !0 from the install function.");
         abort();
     }

     success = g_hash_table_remove(plugin.id_ht, &ctx->id);
     g_assert(success);
     QTAILQ_REMOVE(&plugin.ctxs, ctx, entry);
     if (data->cb) {
         data->cb(ctx->id);
     }
     if (!g_module_close(ctx->handle)) {
         warn_report("%s: %s", __func__, g_module_error());
     }
     plugin_desc_free(ctx->desc);
     qemu_vfree(ctx);
     g_free(data);
 }

 static void plugin_reset_destroy(struct qemu_plugin_reset_data *data)
 {
     qemu_rec_mutex_lock(&plugin.lock);
     plugin_reset_destroy__locked(data);
     qemu_rec_mutex_lock(&plugin.lock);
 }

 static void plugin_flush_destroy(CPUState *cpu, run_on_cpu_data arg)
 {
     struct qemu_plugin_reset_data *data = arg.host_ptr;

     g_assert(cpu_in_exclusive_context(cpu));
     tb_flush(cpu);
     plugin_reset_destroy(data);
 }

 void plugin_reset_uninstall(qemu_plugin_id_t id,
                             qemu_plugin_simple_cb_t cb,
                             bool reset)
 {
     struct qemu_plugin_reset_data *data;
     struct qemu_plugin_ctx *ctx = NULL;

     WITH_QEMU_LOCK_GUARD(&plugin.lock) {
         ctx = plugin_id_to_ctx_locked(id);
         if (ctx->uninstalling || (reset && ctx->resetting)) {
             return;
         }
         ctx->resetting = reset;
         ctx->uninstalling = !reset;
     }

     data = g_new(struct qemu_plugin_reset_data, 1);
     data->ctx = ctx;
     data->cb = cb;
     data->reset = reset;
     /*
      * Only flush the code cache if the vCPUs have been created. If so,
      * current_cpu must be non-NULL.
      */
     if (current_cpu) {
         async_safe_run_on_cpu(current_cpu, plugin_flush_destroy,
                               RUN_ON_CPU_HOST_PTR(data));
     } else {
         /*
          * If current_cpu isn't set, then we don't have yet any vCPU threads
          * and we therefore can remove the callbacks synchronously.
          */
         plugin_reset_destroy(data);
     }
 }
	/*
	* QEMU Plugin Core Loader Code
	*
	* This is the code responsible for loading and unloading the plugins.
	* Aside from the basic housekeeping tasks we also need to ensure any
	* generated code is flushed when we remove a plugin so we cannot end
	* up calling and unloaded helper function.
	*
	* Copyright (C) 2017, Emilio G. Cota <cota@braap.org>
	* Copyright (C) 2019, Linaro
	*
	* License: GNU GPL, version 2 or later.
	* See the COPYING file in the top-level directory.
	*
	* SPDX-License-Identifier: GPL-2.0-or-later
	*/

	#include "qemu/osdep.h"
	#include "qemu/error-report.h"
	#include "qemu/config-file.h"
	#include "qemu/help_option.h"
	#include "qapi/error.h"
	#include "qemu/lockable.h"
	#include "qemu/option.h"
	#include "qemu/rcu_queue.h"
	#include "qemu/qht.h"
	#include "qemu/bitmap.h"
	#include "qemu/cacheinfo.h"
	#include "qemu/xxhash.h"
	#include "qemu/plugin.h"
	#include "qemu/memalign.h"
	#include "hw/core/cpu.h"
	#include "exec/tb-flush.h"
	#ifndef CONFIG_USER_ONLY
	#include "hw/boards.h"
	#endif

	#include "plugin.h"

	/*
	* For convenience we use a bitmap for plugin.mask, but really all we need is a
	* u32, which is what we store in TranslationBlock.
	*/
	QEMU_BUILD_BUG_ON(QEMU_PLUGIN_EV_MAX > 32);

	struct qemu_plugin_desc {
	char *path;
	char **argv;
	QTAILQ_ENTRY(qemu_plugin_desc) entry;
	int argc;
	};

	struct qemu_plugin_parse_arg {
	QemuPluginList *head;
	struct qemu_plugin_desc *curr;
	};

	QemuOptsList qemu_plugin_opts = {
	.name = "plugin",
	.implied_opt_name = "file",
	.head = QTAILQ_HEAD_INITIALIZER(qemu_plugin_opts.head),
	.desc = {
	/* do our own parsing to support multiple plugins */
	{ /* end of list */ }
	},
	};

	typedef int (qemu_plugin_install_func_t)(qemu_plugin_id_t, const qemu_info_t , int, char **);

	extern struct qemu_plugin_state plugin;

	void qemu_plugin_add_dyn_cb_arr(GArray *arr)
	{
	uint32_t hash = qemu_xxhash2((uint64_t)(uintptr_t)arr);
	bool inserted;

	inserted = qht_insert(&plugin.dyn_cb_arr_ht, arr, hash, NULL);
	g_assert(inserted);
	}

	static struct qemu_plugin_desc plugin_find_desc(QemuPluginList head,
	const char *path)
	{
	struct qemu_plugin_desc *desc;

	QTAILQ_FOREACH(desc, head, entry) {
	if (strcmp(desc->path, path) == 0) {
	return desc;
	}
	}
	return NULL;
	}

	static int plugin_add(void opaque, const char name, const char *value,
	Error **errp)
	{
	struct qemu_plugin_parse_arg *arg = opaque;
	struct qemu_plugin_desc *p;
	bool is_on;
	char *fullarg;

	if (is_help_option(value)) {
	printf("Plugin options\n");
	printf(" file=<path/to/plugin.so>\n");
	printf(" plugin specific arguments\n");
	exit(0);
	} else if (strcmp(name, "file") == 0) {
	if (strcmp(value, "") == 0) {
	error_setg(errp, "requires a non-empty argument");
	return 1;
	}
	p = plugin_find_desc(arg->head, value);
	if (p == NULL) {
	p = g_new0(struct qemu_plugin_desc, 1);
	p->path = g_strdup(value);
	QTAILQ_INSERT_TAIL(arg->head, p, entry);
	}
	arg->curr = p;
	} else {
	if (arg->curr == NULL) {
	error_setg(errp, "missing earlier '-plugin file=' option");
	return 1;
	}

	if (g_strcmp0(name, "arg") == 0 &&
	!qapi_bool_parse(name, value, &is_on, NULL)) {
	if (strchr(value, '=') == NULL) {
	/* Will treat arg="argname" as "argname=on" */
	fullarg = g_strdup_printf("%s=%s", value, "on");
	} else {
	fullarg = g_strdup_printf("%s", value);
	}
	warn_report("using 'arg=%s' is deprecated", value);
	error_printf("Please use '%s' directly\n", fullarg);
	} else {
	fullarg = g_strdup_printf("%s=%s", name, value);
	}

	p = arg->curr;
	p->argc++;
	p->argv = g_realloc_n(p->argv, p->argc, sizeof(char *));
	p->argv[p->argc - 1] = fullarg;
	}

	return 0;
	}

	void qemu_plugin_opt_parse(const char optstr, QemuPluginList head)
	{
	struct qemu_plugin_parse_arg arg;
	QemuOpts *opts;

	opts = qemu_opts_parse_noisily(qemu_find_opts("plugin"), optstr, true);
	if (opts == NULL) {
	exit(1);
	}
	arg.head = head;
	arg.curr = NULL;
	qemu_opt_foreach(opts, plugin_add, &arg, &error_fatal);
	qemu_opts_del(opts);
	}

	/*
	* From: https://en.wikipedia.org/wiki/Xorshift
	* This is faster than rand_r(), and gives us a wider range (RAND_MAX is only
	* guaranteed to be >= INT_MAX).
	*/
	static uint64_t xorshift64star(uint64_t x)
	{
	x ^= x >> 12; /* a */
	x ^= x << 25; /* b */
	x ^= x >> 27; /* c */
	return x * UINT64_C(2685821657736338717);
	}

	/*
	* Disable CFI checks.
	* The install and version functions have been loaded from an external library
	* so we do not have type information
	*/
	QEMU_DISABLE_CFI
	static int plugin_load(struct qemu_plugin_desc desc, const qemu_info_t info, Error **errp)
	{
	qemu_plugin_install_func_t install;
	struct qemu_plugin_ctx *ctx;
	gpointer sym;
	int rc;

	ctx = qemu_memalign(qemu_dcache_linesize, sizeof(*ctx));
	memset(ctx, 0, sizeof(*ctx));
	ctx->desc = desc;

	ctx->handle = g_module_open(desc->path, G_MODULE_BIND_LOCAL);
	if (ctx->handle == NULL) {
	error_setg(errp, "Could not load plugin %s: %s", desc->path, g_module_error());
	goto err_dlopen;
	}

	if (!g_module_symbol(ctx->handle, "qemu_plugin_install", &sym)) {
	error_setg(errp, "Could not load plugin %s: %s", desc->path, g_module_error());
	goto err_symbol;
	}
	install = (qemu_plugin_install_func_t) sym;
	/* symbol was found; it could be NULL though */
	if (install == NULL) {
	error_setg(errp, "Could not load plugin %s: qemu_plugin_install is NULL",
	desc->path);
	goto err_symbol;
	}

	if (!g_module_symbol(ctx->handle, "qemu_plugin_version", &sym)) {
	error_setg(errp, "Could not load plugin %s: plugin does not declare API version %s",
	desc->path, g_module_error());
	goto err_symbol;
	} else {
	int version = (int )sym;
	if (version < QEMU_PLUGIN_MIN_VERSION) {
	error_setg(errp, "Could not load plugin %s: plugin requires API version %d, but "
	"this QEMU supports only a minimum version of %d",
	desc->path, version, QEMU_PLUGIN_MIN_VERSION);
	goto err_symbol;
	} else if (version > QEMU_PLUGIN_VERSION) {
	error_setg(errp, "Could not load plugin %s: plugin requires API version %d, but "
	"this QEMU supports only up to version %d",
	desc->path, version, QEMU_PLUGIN_VERSION);
	goto err_symbol;
	}
	}

	qemu_rec_mutex_lock(&plugin.lock);

	/* find an unused random id with &ctx as the seed */
	ctx->id = (uint64_t)(uintptr_t)ctx;
	for (;;) {
	void *existing;

	ctx->id = xorshift64star(ctx->id);
	existing = g_hash_table_lookup(plugin.id_ht, &ctx->id);
	if (likely(existing == NULL)) {
	bool success;

	success = g_hash_table_insert(plugin.id_ht, &ctx->id, &ctx->id);
	g_assert(success);
	break;
	}
	}
	QTAILQ_INSERT_TAIL(&plugin.ctxs, ctx, entry);
	ctx->installing = true;
	rc = install(ctx->id, info, desc->argc, desc->argv);
	ctx->installing = false;
	if (rc) {
	error_setg(errp, "Could not load plugin %s: qemu_plugin_install returned error code %d",
	desc->path, rc);
	/*
	* we cannot rely on the plugin doing its own cleanup, so
	* call a full uninstall if the plugin did not yet call it.
	*/
	if (!ctx->uninstalling) {
	plugin_reset_uninstall(ctx->id, NULL, false);
	}
	}

	qemu_rec_mutex_unlock(&plugin.lock);
	return rc;

	err_symbol:
	g_module_close(ctx->handle);
	err_dlopen:
	qemu_vfree(ctx);
	return 1;
	}

	/* call after having removed @desc from the list */
	static void plugin_desc_free(struct qemu_plugin_desc *desc)
	{
	int i;

	for (i = 0; i < desc->argc; i++) {
	g_free(desc->argv[i]);
	}
	g_free(desc->argv);
	g_free(desc->path);
	g_free(desc);
	}

	/**
	* qemu_plugin_load_list - load a list of plugins
	* @head: head of the list of descriptors of the plugins to be loaded
	*
	* Returns 0 if all plugins in the list are installed, !0 otherwise.
	*
	* Note: the descriptor of each successfully installed plugin is removed
	* from the list given by @head.
	*/
	int qemu_plugin_load_list(QemuPluginList head, Error *errp)
	{
	struct qemu_plugin_desc desc, next;
	g_autofree qemu_info_t *info = g_new0(qemu_info_t, 1);

	info->target_name = TARGET_NAME;
	info->version.min = QEMU_PLUGIN_MIN_VERSION;
	info->version.cur = QEMU_PLUGIN_VERSION;
	#ifndef CONFIG_USER_ONLY
	MachineState *ms = MACHINE(qdev_get_machine());
	info->system_emulation = true;
	info->system.smp_vcpus = ms->smp.cpus;
	info->system.max_vcpus = ms->smp.max_cpus;
	#else
	info->system_emulation = false;
	#endif

	QTAILQ_FOREACH_SAFE(desc, head, entry, next) {
	int err;

	err = plugin_load(desc, info, errp);
	if (err) {
	return err;
	}
	QTAILQ_REMOVE(head, desc, entry);
	}
	return 0;
	}

	struct qemu_plugin_reset_data {
	struct qemu_plugin_ctx *ctx;
	qemu_plugin_simple_cb_t cb;
	bool reset;
	};

	static void plugin_reset_destroy__locked(struct qemu_plugin_reset_data *data)
	{
	struct qemu_plugin_ctx *ctx = data->ctx;
	enum qemu_plugin_event ev;
	bool success;

	/*
	* After updating the subscription lists there is no need to wait for an RCU
	* grace period to elapse, because right now we either are in a "safe async"
	* work environment (i.e. all vCPUs are asleep), or no vCPUs have yet been
	* created.
	*/
	for (ev = 0; ev < QEMU_PLUGIN_EV_MAX; ev++) {
	plugin_unregister_cb__locked(ctx, ev);
	}

	if (data->reset) {
	g_assert(ctx->resetting);
	if (data->cb) {
	data->cb(ctx->id);
	}
	ctx->resetting = false;
	g_free(data);
	return;
	}

	g_assert(ctx->uninstalling);
	/* we cannot dlclose if we are going to return to plugin code */
	if (ctx->installing) {
	error_report("Calling qemu_plugin_uninstall from the install function "
	"is a bug. Instead, return !0 from the install function.");
	abort();
	}

	success = g_hash_table_remove(plugin.id_ht, &ctx->id);
	g_assert(success);
	QTAILQ_REMOVE(&plugin.ctxs, ctx, entry);
	if (data->cb) {
	data->cb(ctx->id);
	}
	if (!g_module_close(ctx->handle)) {
	warn_report("%s: %s", __func__, g_module_error());
	}
	plugin_desc_free(ctx->desc);
	qemu_vfree(ctx);
	g_free(data);
	}

	static void plugin_reset_destroy(struct qemu_plugin_reset_data *data)
	{
	qemu_rec_mutex_lock(&plugin.lock);
	plugin_reset_destroy__locked(data);
	qemu_rec_mutex_lock(&plugin.lock);
	}

	static void plugin_flush_destroy(CPUState *cpu, run_on_cpu_data arg)
	{
	struct qemu_plugin_reset_data *data = arg.host_ptr;

	g_assert(cpu_in_exclusive_context(cpu));
	tb_flush(cpu);
	plugin_reset_destroy(data);
	}

	void plugin_reset_uninstall(qemu_plugin_id_t id,
	qemu_plugin_simple_cb_t cb,
	bool reset)
	{
	struct qemu_plugin_reset_data *data;
	struct qemu_plugin_ctx *ctx = NULL;

	WITH_QEMU_LOCK_GUARD(&plugin.lock) {
	ctx = plugin_id_to_ctx_locked(id);
	if (ctx->uninstalling \|\| (reset && ctx->resetting)) {
	return;
	}
	ctx->resetting = reset;
	ctx->uninstalling = !reset;
	}

	data = g_new(struct qemu_plugin_reset_data, 1);
	data->ctx = ctx;
	data->cb = cb;
	data->reset = reset;
	/*
	* Only flush the code cache if the vCPUs have been created. If so,
	* current_cpu must be non-NULL.
	*/
	if (current_cpu) {
	async_safe_run_on_cpu(current_cpu, plugin_flush_destroy,
	RUN_ON_CPU_HOST_PTR(data));
	} else {
	/*
	* If current_cpu isn't set, then we don't have yet any vCPU threads
	* and we therefore can remove the callbacks synchronously.
	*/
	plugin_reset_destroy(data);
	}
	}