From patchwork Thu Oct 10 06:18:24 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: yaozhenguo X-Patchwork-Id: 13829534 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 3113CCF07A9 for ; Thu, 10 Oct 2024 06:19:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1symVU-0001Yi-9T; Thu, 10 Oct 2024 02:18:40 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1symVO-0001Ve-5m for qemu-devel@nongnu.org; Thu, 10 Oct 2024 02:18:35 -0400 Received: from mail-pl1-x631.google.com ([2607:f8b0:4864:20::631]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1symVM-0000Nm-E1 for qemu-devel@nongnu.org; Thu, 10 Oct 2024 02:18:33 -0400 Received: by mail-pl1-x631.google.com with SMTP id d9443c01a7336-20b9b35c7c7so3475735ad.1 for ; Wed, 09 Oct 2024 23:18:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1728541111; x=1729145911; darn=nongnu.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=MLNiJsGAAWceYJxSps2//DWS3W5RdJ9dtm7PKKVZBoQ=; b=WL4qj9ySBfoQ3lC1b1GwlxZYS9KGyg8wOWfkumjLeH+wEQNxdBu2P6XGBjAePuy0wn b4Q1EziDFowRCoYlzU3CSTktaRTjEXl4bKBA2dblAt40Q6gCVr51LkjchXqg3BAbVyAr 84rnvZGUIwEeG/ZiStXny8sjBfmkgfzq09DcWcYvJDq24ULdKE14c1IO8tr/tm1V+t+U FbY2ZQ4eEferDpGEup1hqBeSLwsgufsQ7Wp9HIBmcWOsIxVyb17HylwhMkKqfvvdycTh T+xtYPZgsnxIfZqq3zfMiHFu9f8aZjtCLvN7sE7Rmr5p4KjmCoazs6IAwtBFDo3UC7B7 OR3Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728541111; x=1729145911; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=MLNiJsGAAWceYJxSps2//DWS3W5RdJ9dtm7PKKVZBoQ=; b=UdVbgHYsFZUK4KMr5wMSafpu8L88fG9jlZMIy9OkvRYl6wLZzjmhiRq8tFZop52QB+ wQm8Kd+80lCGly3uvevio6Zqgab6ku+Z+rt5vvGOyQ0qrXmGGhaoTguX1IkDUcNjGeQS U0l6EcuAaHV3G72MHDBkPzDiakaHs8z8Arbkqv6prBVAZ7eLbBlq0hQyrhIwXV3hxyZ0 jzySN8pyM6wMoL5M1OCqSYA9Cw5tS/0+UsIOjbnsDi80wo1GE7m+bN/l4jwXHEZMub6b R0IrnvWzWa/3mT93A8e0ItmUuSKfv5LRWoaR5TeFIDQCNKykqFy8KGihngLBcVu0GSd2 GO9g== X-Gm-Message-State: AOJu0Yw7kLuNYpX8pvaMjkK+IUEhE978X3ILalTaiHkqluhq7i4XNMrn k7AwzfwbQTrSUxd5It4DLAo91yVLtOd9bB1vuK+vRm+SqEdBkMUv X-Google-Smtp-Source: AGHT+IHrcPiCD2q/3IMA+0pLF3qhHAZbaxI6azAz2xIu/33uK8N53aGDRJ97geVujVGBZ2zDtteDxg== X-Received: by 2002:a17:90b:1245:b0:2e2:c636:d205 with SMTP id 98e67ed59e1d1-2e2c636d34cmr2955663a91.27.1728541110526; Wed, 09 Oct 2024 23:18:30 -0700 (PDT) Received: from localhost.localdomain ([156.59.87.117]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2e2a5aacaebsm2761061a91.39.2024.10.09.23.18.28 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 09 Oct 2024 23:18:30 -0700 (PDT) From: yaozhenguo X-Google-Original-From: yaozhenguo To: alex.bennee@linaro.org, mst@redhat.com, sgarzare@redhat.com Cc: qemu-devel@nongnu.org, yaozhenguo@jd.com Subject: [PATCH V3] virtio/vhost-user: fix qemu abort when hotunplug vhost-user-net device Date: Thu, 10 Oct 2024 14:18:24 +0800 Message-Id: <20241010061824.74819-1-yaozhenguo@jd.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::631; envelope-from=yaozhenguo1@gmail.com; helo=mail-pl1-x631.google.com X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org During the hot-unplugging of vhost-user-net type network cards, the vhost_user_cleanup function may add the same rcu node to the rcu linked list. The function call relationship in this case is as follows: vhost_user_cleanup ->vhost_user_host_notifier_remove ->call_rcu(n, vhost_user_host_notifier_free, rcu); ->g_free_rcu(n, rcu); When this happens, QEMU will abort in try_dequeue: if (head == &dummy && qatomic_mb_read(&tail) == &dummy.next) { abort(); } backtrace is as follows:: 0 __pthread_kill_implementation () at /usr/lib64/libc.so.6 1 raise () at /usr/lib64/libc.so.6 2 abort () at /usr/lib64/libc.so.6 3 try_dequeue () at ../util/rcu.c:235 4 call_rcu_thread (0) at ../util/rcu.c:288 5 qemu_thread_start (0) at ../util/qemu-thread-posix.c:541 6 start_thread () at /usr/lib64/libc.so.6 7 clone3 () at /usr/lib64/libc.so.6 The reason for the abort is that adding two identical nodes to the rcu linked list will cause the rcu linked list to become a ring, but when the dummy node is added after the two identical nodes, the ring is opened. But only one node is added to list with rcu_call_count added twice. This will cause rcu try_dequeue abort. This happens when n->addr != 0. In some scenarios, this does happen. For example, this situation will occur when using a 32-queue DPU vhost-user-net type network card for hot-unplug testing, because VhostUserHostNotifier->addr will be cleared during the processing of VHOST_USER_BACKEND_VRING_HOST_NOTIFIER_MSG. However,it is asynchronous, so we cannot guarantee that VhostUserHostNotifier->addr is zero in vhost_user_cleanup. Therefore, it is necessary to merge g_free_rcu and vhost_user_host_notifier_free into one rcu node. Fixes: 503e355465 ("virtio/vhost-user: dynamically assign VhostUserHostNotifiers") Signed-off-by: yaozhenguo --- V1->V2: add n->addr check in vhost_user_get_vring_base and vhost_user_backend_handle_vring_host_notifier to prevent submit same node to rcu list. V2->V3: 1. change "free" to "destroy" 2. move "!n->addr && !destroy" checking to vhost_user_host_notifier_remove 3. move "!n" checking to vhost_user_host_notifier_remove --- hw/virtio/vhost-user.c | 43 ++++++++++++++++++---------------- include/hw/virtio/vhost-user.h | 1 + 2 files changed, 24 insertions(+), 20 deletions(-) diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 00561daa06..f80d0af76f 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -1185,9 +1185,16 @@ static int vhost_user_set_vring_num(struct vhost_dev *dev, static void vhost_user_host_notifier_free(VhostUserHostNotifier *n) { - assert(n && n->unmap_addr); - munmap(n->unmap_addr, qemu_real_host_page_size()); - n->unmap_addr = NULL; + if (n->unmap_addr) { + munmap(n->unmap_addr, qemu_real_host_page_size()); + n->unmap_addr = NULL; + } + if (n->destroy) { + memory_region_transaction_begin(); + object_unparent(OBJECT(&n->mr)); + memory_region_transaction_commit(); + g_free(n); + } } /* @@ -1195,17 +1202,25 @@ static void vhost_user_host_notifier_free(VhostUserHostNotifier *n) * under rcu. */ static void vhost_user_host_notifier_remove(VhostUserHostNotifier *n, - VirtIODevice *vdev) + VirtIODevice *vdev, bool destroy) { + if (!n) + return; + if (!destroy && !n->addr) + return; + if (n->addr) { if (vdev) { + memory_region_transaction_begin(); virtio_queue_set_host_notifier_mr(vdev, n->idx, &n->mr, false); + memory_region_transaction_commit(); } assert(!n->unmap_addr); n->unmap_addr = n->addr; n->addr = NULL; - call_rcu(n, vhost_user_host_notifier_free, rcu); } + n->destroy = destroy; + call_rcu(n, vhost_user_host_notifier_free, rcu); } static int vhost_user_set_vring_base(struct vhost_dev *dev, @@ -1279,9 +1294,7 @@ static int vhost_user_get_vring_base(struct vhost_dev *dev, struct vhost_user *u = dev->opaque; VhostUserHostNotifier *n = fetch_notifier(u->user, ring->index); - if (n) { - vhost_user_host_notifier_remove(n, dev->vdev); - } + vhost_user_host_notifier_remove(n, dev->vdev, false); ret = vhost_user_write(dev, &msg, NULL, 0); if (ret < 0) { @@ -1562,7 +1575,7 @@ static int vhost_user_backend_handle_vring_host_notifier(struct vhost_dev *dev, * new mapped address. */ n = fetch_or_create_notifier(user, queue_idx); - vhost_user_host_notifier_remove(n, vdev); + vhost_user_host_notifier_remove(n, vdev, false); if (area->u64 & VHOST_USER_VRING_NOFD_MASK) { return 0; @@ -2736,15 +2749,7 @@ static int vhost_user_set_inflight_fd(struct vhost_dev *dev, static void vhost_user_state_destroy(gpointer data) { VhostUserHostNotifier *n = (VhostUserHostNotifier *) data; - if (n) { - vhost_user_host_notifier_remove(n, NULL); - object_unparent(OBJECT(&n->mr)); - /* - * We can't free until vhost_user_host_notifier_remove has - * done it's thing so schedule the free with RCU. - */ - g_free_rcu(n, rcu); - } + vhost_user_host_notifier_remove(n, NULL, true); } bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp) @@ -2765,9 +2770,7 @@ void vhost_user_cleanup(VhostUserState *user) if (!user->chr) { return; } - memory_region_transaction_begin(); user->notifiers = (GPtrArray *) g_ptr_array_free(user->notifiers, true); - memory_region_transaction_commit(); user->chr = NULL; } diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h index 324cd8663a..9a3f238b43 100644 --- a/include/hw/virtio/vhost-user.h +++ b/include/hw/virtio/vhost-user.h @@ -54,6 +54,7 @@ typedef struct VhostUserHostNotifier { void *addr; void *unmap_addr; int idx; + bool destroy; } VhostUserHostNotifier; /**