From nobody Thu Dec 18 01:37:30 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8329A239E8C for ; Sat, 31 May 2025 09:52:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748685123; cv=none; b=iA04olRjwTi33uTVnrMo48bGn7d+s74RIMejpikFq76q73Uz7B0NeSz9S/W0C5PkGKoWv/iDO7wulUjJtav7IXXalWxBkHxCMJxRpwBIkdZU1YDgR3Presvx4dFihmQLr2UjXhhxQuyT7uX3xSWu4G4nA65f0Dlhayah6GaD18Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748685123; c=relaxed/simple; bh=CcOpk8Xyc4VMwwKi2VpRLuGbaZey2YlSpo+8aANMhkg=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=p562dXq/gKeRQPcuznT4gNOITgTWRYaf+CAKy0jNAaRt+CkXCPMD1v26wYIJ1PLXMN9cl/fC5mSyes9evZAYaRZ2AReLA08smaRG+a6VjfSdO+dr5Be+iEnFXQy6JqMNtRvtiXYDYexGDVi6fFOt+4puJEgPzF4TLCGpPiQpdNU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=MxG0sRSW; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MxG0sRSW" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1748685120; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/eIhXFNCsuT8fyAjm28qjbco9E563cRybykc6t/pZX4=; b=MxG0sRSWduBI5cA+lgZvDCXG+YexLfiHxdH+3HMK3ZjA1V+nLQd4cc//RjMNt+gLe5wv1X Y524+j2O0HQ0ioaw4cDct2EWoewPjlfgxStcBTVDUjsA88NQzNHo/41RTVOqfcwAPlMs1N krkwgmFC8dLXN0RJwA5iKAFcMWwg6m0= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-193-0rYBKxYlP_KOS9jjQYB26w-1; Sat, 31 May 2025 05:51:59 -0400 X-MC-Unique: 0rYBKxYlP_KOS9jjQYB26w-1 X-Mimecast-MFC-AGG-ID: 0rYBKxYlP_KOS9jjQYB26w_1748685118 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 088BC1800446; Sat, 31 May 2025 09:51:58 +0000 (UTC) Received: from server.redhat.com (unknown [10.72.112.30]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id EAB90180049D; Sat, 31 May 2025 09:51:53 +0000 (UTC) From: Cindy Lu To: lulu@redhat.com, jasowang@redhat.com, mst@redhat.com, michael.christie@oracle.com, sgarzare@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH v10 2/3] vhost: Reintroduce kthread mode support in vhost Date: Sat, 31 May 2025 17:47:04 +0800 Message-ID: <20250531095135.159582-3-lulu@redhat.com> In-Reply-To: <20250531095135.159582-1-lulu@redhat.com> References: <20250531095135.159582-1-lulu@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 This patch reintroduces kthread mode support in vhost, It also introduces struct vhost_worker_ops to abstract worker create/stop/wakeup operations. * Bring back the original vhost_worker() implementation, and renamed to vhost_run_work_kthread_list(). * Add cgroup support for the kthread * Introduce struct vhost_worker_ops: - Encapsulates create / stop / wake=E2=80=91up callbacks. - vhost_worker_create() selects the proper ops according to inherit_owner. This partially reverts or improves upon: commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads") commit 1cdaafa1b8b4 ("vhost: replace single worker pointer with xarray") Signed-off-by: Cindy Lu --- drivers/vhost/vhost.c | 188 ++++++++++++++++++++++++++++++++++++++---- drivers/vhost/vhost.h | 12 +++ 2 files changed, 182 insertions(+), 18 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 240ba78b1e3f..2d2909be1bb2 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -246,7 +247,7 @@ static void vhost_worker_queue(struct vhost_worker *wor= ker, * test_and_set_bit() implies a memory barrier. */ llist_add(&work->node, &worker->work_list); - vhost_task_wake(worker->vtsk); + worker->ops->wakeup(worker); } } =20 @@ -392,6 +393,44 @@ static void vhost_vq_reset(struct vhost_dev *dev, __vhost_vq_meta_reset(vq); } =20 +static int vhost_run_work_kthread_list(void *data) +{ + struct vhost_worker *worker =3D data; + struct vhost_work *work, *work_next; + struct vhost_dev *dev =3D worker->dev; + struct llist_node *node; + + kthread_use_mm(dev->mm); + + for (;;) { + /* mb paired w/ kthread_stop */ + set_current_state(TASK_INTERRUPTIBLE); + + if (kthread_should_stop()) { + __set_current_state(TASK_RUNNING); + break; + } + node =3D llist_del_all(&worker->work_list); + if (!node) + schedule(); + + node =3D llist_reverse_order(node); + /* make sure flag is seen after deletion */ + smp_wmb(); + llist_for_each_entry_safe(work, work_next, node, node) { + clear_bit(VHOST_WORK_QUEUED, &work->flags); + __set_current_state(TASK_RUNNING); + kcov_remote_start_common(worker->kcov_handle); + work->fn(work); + kcov_remote_stop(); + cond_resched(); + } + } + kthread_unuse_mm(dev->mm); + + return 0; +} + static bool vhost_run_work_list(void *data) { struct vhost_worker *worker =3D data; @@ -586,6 +625,46 @@ long vhost_dev_check_owner(struct vhost_dev *dev) } EXPORT_SYMBOL_GPL(vhost_dev_check_owner); =20 +struct vhost_attach_cgroups_struct { + struct vhost_work work; + struct task_struct *owner; + int ret; +}; + +static void vhost_attach_cgroups_work(struct vhost_work *work) +{ + struct vhost_attach_cgroups_struct *s; + + s =3D container_of(work, struct vhost_attach_cgroups_struct, work); + s->ret =3D cgroup_attach_task_all(s->owner, current); +} + +static int vhost_attach_task_to_cgroups(struct vhost_worker *worker) +{ + struct vhost_attach_cgroups_struct attach; + int saved_cnt; + + attach.owner =3D current; + + vhost_work_init(&attach.work, vhost_attach_cgroups_work); + vhost_worker_queue(worker, &attach.work); + + mutex_lock(&worker->mutex); + + /* + * Bypass attachment_cnt check in __vhost_worker_flush: + * Temporarily change it to INT_MAX to bypass the check + */ + saved_cnt =3D worker->attachment_cnt; + worker->attachment_cnt =3D INT_MAX; + __vhost_worker_flush(worker); + worker->attachment_cnt =3D saved_cnt; + + mutex_unlock(&worker->mutex); + + return attach.ret; +} + /* Caller should have device mutex */ bool vhost_dev_has_owner(struct vhost_dev *dev) { @@ -631,7 +710,7 @@ static void vhost_worker_destroy(struct vhost_dev *dev, =20 WARN_ON(!llist_empty(&worker->work_list)); xa_erase(&dev->worker_xa, worker->id); - vhost_task_stop(worker->vtsk); + worker->ops->stop(worker); kfree(worker); } =20 @@ -654,42 +733,115 @@ static void vhost_workers_free(struct vhost_dev *dev) xa_destroy(&dev->worker_xa); } =20 +static void vhost_task_wakeup(struct vhost_worker *worker) +{ + return vhost_task_wake(worker->vtsk); +} + +static void vhost_kthread_wakeup(struct vhost_worker *worker) +{ + wake_up_process(worker->kthread_task); +} + +static void vhost_task_do_stop(struct vhost_worker *worker) +{ + return vhost_task_stop(worker->vtsk); +} + +static void vhost_kthread_do_stop(struct vhost_worker *worker) +{ + kthread_stop(worker->kthread_task); +} + +static int vhost_task_worker_create(struct vhost_worker *worker, + struct vhost_dev *dev, const char *name) +{ + struct vhost_task *vtsk; + u32 id; + int ret; + + vtsk =3D vhost_task_create(vhost_run_work_list, vhost_worker_killed, + worker, name); + if (IS_ERR(vtsk)) + return PTR_ERR(vtsk); + + worker->vtsk =3D vtsk; + vhost_task_start(vtsk); + ret =3D xa_alloc(&dev->worker_xa, &id, worker, xa_limit_32b, GFP_KERNEL); + if (ret < 0) { + vhost_task_do_stop(worker); + return ret; + } + worker->id =3D id; + return 0; +} + +static int vhost_kthread_worker_create(struct vhost_worker *worker, + struct vhost_dev *dev, const char *name) +{ + struct task_struct *task; + u32 id; + int ret; + + task =3D kthread_create(vhost_run_work_kthread_list, worker, "%s", name); + if (IS_ERR(task)) + return PTR_ERR(task); + + worker->kthread_task =3D task; + wake_up_process(task); + ret =3D xa_alloc(&dev->worker_xa, &id, worker, xa_limit_32b, GFP_KERNEL); + if (ret < 0) + goto stop_worker; + + ret =3D vhost_attach_task_to_cgroups(worker); + if (ret) + goto stop_worker; + + worker->id =3D id; + return 0; + +stop_worker: + vhost_kthread_do_stop(worker); + return ret; +} + +static const struct vhost_worker_ops kthread_ops =3D { + .create =3D vhost_kthread_worker_create, + .stop =3D vhost_kthread_do_stop, + .wakeup =3D vhost_kthread_wakeup, +}; + +static const struct vhost_worker_ops vhost_task_ops =3D { + .create =3D vhost_task_worker_create, + .stop =3D vhost_task_do_stop, + .wakeup =3D vhost_task_wakeup, +}; + static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev) { struct vhost_worker *worker; - struct vhost_task *vtsk; char name[TASK_COMM_LEN]; int ret; - u32 id; + const struct vhost_worker_ops *ops =3D + dev->inherit_owner ? &vhost_task_ops : &kthread_ops; =20 worker =3D kzalloc(sizeof(*worker), GFP_KERNEL_ACCOUNT); if (!worker) return NULL; =20 worker->dev =3D dev; + worker->ops =3D ops; snprintf(name, sizeof(name), "vhost-%d", current->pid); =20 - vtsk =3D vhost_task_create(vhost_run_work_list, vhost_worker_killed, - worker, name); - if (IS_ERR(vtsk)) - goto free_worker; - mutex_init(&worker->mutex); init_llist_head(&worker->work_list); worker->kcov_handle =3D kcov_common_handle(); - worker->vtsk =3D vtsk; - - vhost_task_start(vtsk); - - ret =3D xa_alloc(&dev->worker_xa, &id, worker, xa_limit_32b, GFP_KERNEL); + ret =3D ops->create(worker, dev, name); if (ret < 0) - goto stop_worker; - worker->id =3D id; + goto free_worker; =20 return worker; =20 -stop_worker: - vhost_task_stop(vtsk); free_worker: kfree(worker); return NULL; diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index c1ff4a92b925..bef42ed51485 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -26,7 +26,18 @@ struct vhost_work { unsigned long flags; }; =20 +struct vhost_worker; +struct vhost_dev; + +struct vhost_worker_ops { + int (*create)(struct vhost_worker *worker, struct vhost_dev *dev, + const char *name); + void (*stop)(struct vhost_worker *worker); + void (*wakeup)(struct vhost_worker *worker); +}; + struct vhost_worker { + struct task_struct *kthread_task; struct vhost_task *vtsk; struct vhost_dev *dev; /* Used to serialize device wide flushing with worker swapping. */ @@ -36,6 +47,7 @@ struct vhost_worker { u32 id; int attachment_cnt; bool killed; + const struct vhost_worker_ops *ops; }; =20 /* Poll a file (eventfd or socket) */ --=20 2.45.0