From patchwork Thu Jul 21 12:07:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 12925033 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5C656C433EF for ; Thu, 21 Jul 2022 12:14:23 +0000 (UTC) Received: from localhost ([::1]:41764 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oEV4Q-0004oP-EY for qemu-devel@archiver.kernel.org; Thu, 21 Jul 2022 08:14:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59264) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oEUyF-0002Ax-Dv for qemu-devel@nongnu.org; Thu, 21 Jul 2022 08:07:59 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:38865) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oEUyD-0000xk-3f for qemu-devel@nongnu.org; Thu, 21 Jul 2022 08:07:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1658405276; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hBbRe241oIn6dwfW5KLA9nuMpaschDSBDr3Vcja/5Ec=; b=SOnqMuwQFaVn+qTubpzyXZ3BrHKh/1w8xz4Vk4O9YvqLzRYwRH+KKf0QgkPYCIDYFDMFk/ U6sVh5x+jIMp+xVgDDoonBLYuqA7KLgPUu0XzG3LyRSy0rieBb17XzRAH6AvRADHGgOkC7 lalmFnbQNZCi/IZJPJi/INCDwTgjwX8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-184-5CcNNtQwPnKHNNyvZFKzkQ-1; Thu, 21 Jul 2022 08:07:46 -0400 X-MC-Unique: 5CcNNtQwPnKHNNyvZFKzkQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C37A0811E81; Thu, 21 Jul 2022 12:07:45 +0000 (UTC) Received: from t480s.fritz.box (unknown [10.39.193.182]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3044A2026D64; Thu, 21 Jul 2022 12:07:43 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Cc: David Hildenbrand , Michal Privoznik , Igor Mammedov , "Michael S. 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David Alan Gilbert" , Eric Blake , Markus Armbruster , Richard Henderson , Stefan Weil Subject: [PATCH RFC 3/7] util: Introduce ThreadContext user-creatable object Date: Thu, 21 Jul 2022 14:07:28 +0200 Message-Id: <20220721120732.118133-4-david@redhat.com> In-Reply-To: <20220721120732.118133-1-david@redhat.com> References: <20220721120732.118133-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 Received-SPF: pass client-ip=170.10.133.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Setting the CPU affinity of QEMU threads is a bit problematic, because QEMU doesn't always have permissions to set the CPU affinity itself, for example, with seccomp after initialized by QEMU: -sandbox enable=on,resourcecontrol=deny While upper layers are already aware how to handl;e CPU affinities for long-lived threads like iothreads or vcpu threads, especially short-lived threads, as used for memory-backend preallocation, are more involved to handle. These threads are created on demand and upper layers are not even able to identify and configure them. Introduce the concept of a ThreadContext, that is essentially a thread used for creating new threads. All threads created via that context thread inherit the configured CPU affinity. Consequently, it's sufficient to create a ThreadContext and configure it once, and have all threads created via that ThreadContext inherit the same CPU affinity. The CPU affinity of a ThreadContext can be configured two ways: (1) Obtaining the thread id via the "thread-id" property and setting the CPU affinity manually. (2) Setting the "cpu-affinity" property and letting QEMU try set the CPU affinity itself. This will fail if QEMU doesn't have permissions to do so anymore after seccomp was initialized. A ThreadContext can be reused, simply be reconfiguring the CPU affinity. Signed-off-by: David Hildenbrand --- include/qemu/thread-context.h | 58 +++++++ qapi/qom.json | 16 ++ util/meson.build | 1 + util/oslib-posix.c | 1 + util/thread-context.c | 279 ++++++++++++++++++++++++++++++++++ 5 files changed, 355 insertions(+) create mode 100644 include/qemu/thread-context.h create mode 100644 util/thread-context.c diff --git a/include/qemu/thread-context.h b/include/qemu/thread-context.h new file mode 100644 index 0000000000..c799cbe7a1 --- /dev/null +++ b/include/qemu/thread-context.h @@ -0,0 +1,58 @@ +/* + * QEMU Thread Context + * + * Copyright Red Hat Inc., 2022 + * + * Authors: + * David Hildenbrand + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + */ + +#ifndef SYSEMU_THREAD_CONTEXT_H +#define SYSEMU_THREAD_CONTEXT_H + +#include "qapi/qapi-types-machine.h" +#include "qemu/thread.h" +#include "qom/object.h" + +#define TYPE_THREAD_CONTEXT "thread-context" +OBJECT_DECLARE_TYPE(ThreadContext, ThreadContextClass, + THREAD_CONTEXT) + +struct ThreadContextClass { + ObjectClass parent_class; +}; + +struct ThreadContext { + /* private */ + Object parent; + + /* private */ + unsigned int thread_id; + QemuThread thread; + + /* Semaphore to wait for context thread action. */ + QemuSemaphore sem; + /* Semaphore to wait for action in context thread. */ + QemuSemaphore sem_thread; + /* Mutex to synchronize requests. */ + QemuMutex mutex; + + /* Commands for the thread to execute. */ + int thread_cmd; + void *thread_cmd_data; + + /* CPU affinity bitmap used for initialization. */ + unsigned long *init_cpu_bitmap; + int init_cpu_nbits; +}; + +void thread_context_create_thread(ThreadContext *tc, QemuThread *thread, + const char *name, + void *(*start_routine)(void *), void *arg, + int mode); + +#endif /* SYSEMU_THREAD_CONTEXT_H */ diff --git a/qapi/qom.json b/qapi/qom.json index 80dd419b39..4775a333ed 100644 --- a/qapi/qom.json +++ b/qapi/qom.json @@ -830,6 +830,20 @@ 'reduced-phys-bits': 'uint32', '*kernel-hashes': 'bool' } } +## +# @ThreadContextProperties: +# +# Properties for thread context objects. +# +# @cpu-affinity: the CPU affinity for all threads created in the thread +# context (default: QEMU main thread affinity) +# +# Since: 7.2 +## +{ 'struct': 'ThreadContextProperties', + 'data': { '*cpu-affinity': ['uint16'] } } + + ## # @ObjectType: # @@ -882,6 +896,7 @@ { 'name': 'secret_keyring', 'if': 'CONFIG_SECRET_KEYRING' }, 'sev-guest', + 'thread-context', 's390-pv-guest', 'throttle-group', 'tls-creds-anon', @@ -948,6 +963,7 @@ 'secret_keyring': { 'type': 'SecretKeyringProperties', 'if': 'CONFIG_SECRET_KEYRING' }, 'sev-guest': 'SevGuestProperties', + 'thread-context': 'ThreadContextProperties', 'throttle-group': 'ThrottleGroupProperties', 'tls-creds-anon': 'TlsCredsAnonProperties', 'tls-creds-psk': 'TlsCredsPskProperties', diff --git a/util/meson.build b/util/meson.build index 5e282130df..e97cd2d779 100644 --- a/util/meson.build +++ b/util/meson.build @@ -1,4 +1,5 @@ util_ss.add(files('osdep.c', 'cutils.c', 'unicode.c', 'qemu-timer-common.c')) +util_ss.add(files('thread-context.c')) if not config_host_data.get('CONFIG_ATOMIC64') util_ss.add(files('atomic64.c')) endif diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 75e8cdcf3e..fa66f73bf8 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -42,6 +42,7 @@ #include "qemu/cutils.h" #include "qemu/compiler.h" #include "qemu/units.h" +#include "qemu/thread-context.h" #ifdef CONFIG_LINUX #include diff --git a/util/thread-context.c b/util/thread-context.c new file mode 100644 index 0000000000..dcd607c532 --- /dev/null +++ b/util/thread-context.c @@ -0,0 +1,279 @@ +/* + * QEMU Thread Context + * + * Copyright Red Hat Inc., 2022 + * + * Authors: + * David Hildenbrand + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + */ + +#include "qemu/osdep.h" +#include "qemu/thread-context.h" +#include "qapi/error.h" +#include "qapi/qapi-builtin-visit.h" +#include "qapi/visitor.h" +#include "qemu/config-file.h" +#include "qapi/qapi-builtin-visit.h" +#include "qom/object_interfaces.h" +#include "qemu/module.h" +#include "qemu/bitmap.h" + +enum { + TC_CMD_NONE = 0, + TC_CMD_STOP, + TC_CMD_NEW, +}; + +typedef struct ThreadContextCmdNew { + QemuThread *thread; + const char *name; + void *(*start_routine)(void *); + void *arg; + int mode; +} ThreadContextCmdNew; + +static void *thread_context_run(void *opaque) +{ + ThreadContext *tc = opaque; + + tc->thread_id = qemu_get_thread_id(); + qemu_sem_post(&tc->sem); + + while (true) { + /* + * Threads inherit the CPU affinity of the creating thread. For this + * reason, we create new (especially short-lived) threads from our + * persistent context thread. + * + * Especially when QEMU is not allowed to set the affinity itself, + * management tools can simply set the affinity of the context thread + * after creating the context, to have new threads created via + * the context inherit the CPU affinity automatically. + */ + switch (tc->thread_cmd) { + case TC_CMD_NONE: + break; + case TC_CMD_STOP: + tc->thread_cmd = TC_CMD_NONE; + qemu_sem_post(&tc->sem); + return NULL; + case TC_CMD_NEW: { + ThreadContextCmdNew *cmd_new = tc->thread_cmd_data; + + qemu_thread_create(cmd_new->thread, cmd_new->name, + cmd_new->start_routine, cmd_new->arg, + cmd_new->mode); + tc->thread_cmd = TC_CMD_NONE; + tc->thread_cmd_data = NULL; + qemu_sem_post(&tc->sem); + break; + } + default: + g_assert_not_reached(); + } + qemu_sem_wait(&tc->sem_thread); + } +} + +static void thread_context_set_cpu_affinity(Object *obj, Visitor *v, + const char *name, void *opaque, + Error **errp) +{ + ThreadContext *tc = THREAD_CONTEXT(obj); + uint16List *l, *host_cpus = NULL; + unsigned long *bitmap = NULL; + int nbits = 0, ret; + Error *err = NULL; + + visit_type_uint16List(v, name, &host_cpus, &err); + if (err) { + error_propagate(errp, err); + return; + } + + if (!host_cpus) { + error_setg(errp, "CPU list is empty"); + goto out; + } + + for (l = host_cpus; l; l = l->next) { + nbits = MAX(nbits, l->value + 1); + } + bitmap = bitmap_new(nbits); + for (l = host_cpus; l; l = l->next) { + set_bit(l->value, bitmap); + } + + if (tc->thread_id != -1) { + /* + * Note: we won't be adjusting the affinity of any thread that is still + * around, but only the affinity of the context thread. + */ + ret = qemu_thread_set_affinity(&tc->thread, bitmap, nbits); + if (ret) { + error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret)); + } + } else { + tc->init_cpu_bitmap = bitmap; + bitmap = NULL; + tc->init_cpu_nbits = nbits; + } +out: + g_free(bitmap); + qapi_free_uint16List(host_cpus); +} + +static void thread_context_get_cpu_affinity(Object *obj, Visitor *v, + const char *name, void *opaque, + Error **errp) +{ + unsigned long *bitmap, nbits, value; + ThreadContext *tc = THREAD_CONTEXT(obj); + uint16List *host_cpus = NULL; + uint16List **tail = &host_cpus; + int ret; + + if (tc->thread_id == -1) { + error_setg(errp, "Object not initialized yet"); + return; + } + + ret = qemu_thread_get_affinity(&tc->thread, &bitmap, &nbits); + if (ret) { + error_setg(errp, "Getting CPU affinity failed: %s", strerror(ret)); + return; + } + + value = find_first_bit(bitmap, nbits); + while (value < nbits) { + QAPI_LIST_APPEND(tail, value); + + value = find_next_bit(bitmap, nbits, value + 1); + } + g_free(bitmap); + + visit_type_uint16List(v, name, &host_cpus, errp); + qapi_free_uint16List(host_cpus); +} + +static void thread_context_get_thread_id(Object *obj, Visitor *v, + const char *name, void *opaque, + Error **errp) +{ + ThreadContext *tc = THREAD_CONTEXT(obj); + uint64_t value = tc->thread_id; + + visit_type_uint64(v, name, &value, errp); +} + +static void thread_context_instance_complete(UserCreatable *uc, Error **errp) +{ + ThreadContext *tc = THREAD_CONTEXT(uc); + char *thread_name; + int ret; + + thread_name = g_strdup_printf("TC %s", + object_get_canonical_path_component(OBJECT(uc))); + qemu_thread_create(&tc->thread, thread_name, thread_context_run, tc, + QEMU_THREAD_JOINABLE); + g_free(thread_name); + + /* Wait until initialization of the thread is done. */ + while (tc->thread_id == -1) { + qemu_sem_wait(&tc->sem); + } + + if (tc->init_cpu_bitmap) { + ret = qemu_thread_set_affinity(&tc->thread, tc->init_cpu_bitmap, + tc->init_cpu_nbits); + if (ret) { + error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret)); + } + g_free(tc->init_cpu_bitmap); + tc->init_cpu_bitmap = NULL; + } +} + +static void thread_context_class_init(ObjectClass *oc, void *data) +{ + UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc); + + ucc->complete = thread_context_instance_complete; + object_class_property_add(oc, "thread-id", "int", + thread_context_get_thread_id, NULL, NULL, + NULL); + object_class_property_add(oc, "cpu-affinity", "int", + thread_context_get_cpu_affinity, + thread_context_set_cpu_affinity, NULL, NULL); +} + +static void thread_context_instance_init(Object *obj) +{ + ThreadContext *tc = THREAD_CONTEXT(obj); + + tc->thread_id = -1; + qemu_sem_init(&tc->sem, 0); + qemu_sem_init(&tc->sem_thread, 0); + qemu_mutex_init(&tc->mutex); +} + +static void thread_context_instance_finalize(Object *obj) +{ + ThreadContext *tc = THREAD_CONTEXT(obj); + + if (tc->thread_id != -1) { + tc->thread_cmd = TC_CMD_STOP; + qemu_sem_post(&tc->sem_thread); + qemu_thread_join(&tc->thread); + } + qemu_sem_destroy(&tc->sem); + qemu_sem_destroy(&tc->sem_thread); + qemu_mutex_destroy(&tc->mutex); +} + +static const TypeInfo thread_context_info = { + .name = TYPE_THREAD_CONTEXT, + .parent = TYPE_OBJECT, + .class_init = thread_context_class_init, + .instance_size = sizeof(ThreadContext), + .instance_init = thread_context_instance_init, + .instance_finalize = thread_context_instance_finalize, + .interfaces = (InterfaceInfo[]) { + { TYPE_USER_CREATABLE }, + { } + } +}; + +static void thread_context_register_types(void) +{ + type_register_static(&thread_context_info); +} +type_init(thread_context_register_types) + +void thread_context_create_thread(ThreadContext *tc, QemuThread *thread, + const char *name, + void *(*start_routine)(void *), void *arg, + int mode) +{ + ThreadContextCmdNew data = { + .thread = thread, + .name = name, + .start_routine = start_routine, + .arg = arg, + .mode = mode, + }; + + qemu_mutex_lock(&tc->mutex); + tc->thread_cmd = TC_CMD_NEW; + tc->thread_cmd_data = &data; + qemu_sem_post(&tc->sem_thread); + + while (tc->thread_cmd != TC_CMD_NONE) { + qemu_sem_wait(&tc->sem); + } + qemu_mutex_unlock(&tc->mutex); +}