From patchwork Fri Sep 13 08:08:00 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: yaozhenguo X-Patchwork-Id: 13803083 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 96C0FFA372A for ; Fri, 13 Sep 2024 08:09:04 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sp1M4-0005EQ-BX; Fri, 13 Sep 2024 04:08:36 -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 1sp1M2-0005DD-CY for qemu-devel@nongnu.org; Fri, 13 Sep 2024 04:08:34 -0400 Received: from mail-pf1-x432.google.com ([2607:f8b0:4864:20::432]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1sp1M0-0004kU-KA for qemu-devel@nongnu.org; Fri, 13 Sep 2024 04:08:34 -0400 Received: by mail-pf1-x432.google.com with SMTP id d2e1a72fcca58-7178df70f28so1445437b3a.2 for ; Fri, 13 Sep 2024 01:08:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1726214911; x=1726819711; 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=8AXURNAi+BDX4azNt4WUsGR8sMriNn0bmqexN5+D+MU=; b=VFWJAkHqkN9iQJrpVE/S5dJMHSzJIS7gj+yMTuChcA7UMMlO593bXlt2JFFutw5ezi rdQXTgz40V9STm+B0LhJjSVU3F4Xfd/tJoaNFLxg1juK0BcrA2WY5FB1SJlB91Q+4YqJ nOB/mQpsWErd6Erw35DlG6iZAbqOTnWMVAuyhAgw0C+a2mOH5BVK6rAWCw83jU1cxrYy pa0n1D64bzJaj5EIFRzKmvaAgVN+pojG6AiYAgjnhkqw9fSbgyjU7okbmznw5Iy5K1X3 G39S5TGlTjqDRfvh2moQTUwuQjzRCvMCugRrTo7tIOU0eeTKIvkhIim8qpeAIcgMMjOs zEnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1726214911; x=1726819711; 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=8AXURNAi+BDX4azNt4WUsGR8sMriNn0bmqexN5+D+MU=; b=I5b1bXKZvzf9SWwG7UChPQOMomXcGFTcwdsWM39FwRTU662sTy5u7DgsNts20d1act itd+VEyFSeF6Y/rIxEm+fgpuBUeS+NKt5AiO2q4F4d9IV2rtZ8d2z8iAzgHUBZzFZiqC U1NmP3t/ed983xav5IEYwnOlrJJJ2a0AhMu5XdfMjHF06TQfO7G9p1qNI1NRbJZgPZNR pHAMUYjN8hzI8Bidr0x3Uw+ruqtzY/FPaePvzwSYhbXIyjW5mlSX2fprobBeZCaZdE+5 RFa1qIx46O+DXK7aMTPMuOBZ4ikaqMQW/S3C/OI2/59Zq7w+gz6ToCDe2PD6m7GAat1N N8/Q== X-Gm-Message-State: AOJu0YzAlDbh0/m3RvoTx4qRYL8D3hicKpTGGupU1QC587IDJQB/j7Uk m4tvUwvfxwQUsO9+K+M2b2CUF8uB4xO5OozZb4JCXHtxkLUcMoXV X-Google-Smtp-Source: AGHT+IHL65v/9Y4IZomWevQGvrRZUSTaCw0v5jp2mqo5STr3Ewzvz/9FN+hi/reohBDN0cJSdaTLwg== X-Received: by 2002:a05:6a20:ac43:b0:1cf:36f2:21e9 with SMTP id adf61e73a8af0-1cf76358fdfmr7223972637.32.1726214910634; Fri, 13 Sep 2024 01:08:30 -0700 (PDT) Received: from localhost.localdomain ([2408:80e0:41fc:0:fe2d:0:1:8699]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-71908fe5309sm5635701b3a.84.2024.09.13.01.08.28 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 13 Sep 2024 01:08:30 -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 V1] virtio/vhost-user: fix qemu abort when hotunplug vhost-user-net device Date: Fri, 13 Sep 2024 16:08:00 +0800 Message-Id: <20240913080800.40816-1-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::432; envelope-from=yaozhenguo1@gmail.com; helo=mail-pf1-x432.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 process of hot-unplug in vhost-user-net NIC, vhost_user_cleanup may add same rcu node to rcu list. Function calls are 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 Reason for the abort is that adding two identical nodes to the rcu list will cause it becomes a ring. After dummy node is added to the tail of the list in try_dequeue, the ring is opened. But lead to a situation that only one node is added to list and rcu_call_count is added twice. This will cause try_dequeue abort. This issue happens when n->addr != 0 in vhost_user_host_notifier_remove. It can happens in a hotplug stress test with a 32queue vhost-user-net type NIC. Because n->addr is set in VHOST_USER_BACKEND_VRING_HOST_NOTIFIER_MSG function. during device hotplug process and it is cleared in vhost_dev_stop during device hot-unplug. Since VHOST_USER_BACKEND_VRING_HOST_NOTIFIER_MSG is a message sent by DPDK to qemu, it is asynchronous. So, there is no guaranteed order between the two processes of setting n->addr and clearing n->addr. If setting n->addr in hotplug occurs after clearing n->addr in hotunplug, the issue will occur. So, 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 --- hw/virtio/vhost-user.c | 34 ++++++++++++++++++---------------- include/hw/virtio/vhost-user.h | 1 + 2 files changed, 19 insertions(+), 16 deletions(-) diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 00561da..b2da3cf 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->need_free) { + memory_region_transaction_begin(); + object_unparent(OBJECT(&n->mr)); + memory_region_transaction_commit(); + g_free(n); + } } /* @@ -1195,17 +1202,20 @@ 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 free) { 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->need_free = free; + call_rcu(n, vhost_user_host_notifier_free, rcu); } static int vhost_user_set_vring_base(struct vhost_dev *dev, @@ -1280,7 +1290,7 @@ static int vhost_user_get_vring_base(struct vhost_dev *dev, 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); @@ -1562,7 +1572,7 @@ 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; @@ -2737,13 +2747,7 @@ 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); } } @@ -2765,9 +2769,7 @@ 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 324cd86..a171f29 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 need_free; } VhostUserHostNotifier; /**