From patchwork Fri Sep 6 06:53:46 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Tokarev X-Patchwork-Id: 13793464 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 34A3DCE7AE0 for ; Fri, 6 Sep 2024 07:00:53 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1smSsv-0000ai-Kx; Fri, 06 Sep 2024 02:55:57 -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 1smSsr-0000EA-IJ; Fri, 06 Sep 2024 02:55:53 -0400 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1smSso-0003I0-N8; Fri, 06 Sep 2024 02:55:53 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id A9C438C245; Fri, 6 Sep 2024 09:53:12 +0300 (MSK) Received: from tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with SMTP id 668351333FD; Fri, 6 Sep 2024 09:54:30 +0300 (MSK) Received: (nullmailer pid 43424 invoked by uid 1000); Fri, 06 Sep 2024 06:54:29 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Thomas Huth , Manos Pitsidianakis , "Michael S . Tsirkin" , Michael Tokarev Subject: [Stable-8.2.7 16/53] hw/virtio: Fix the de-initialization of vhost-user devices Date: Fri, 6 Sep 2024 09:53:46 +0300 Message-Id: <20240906065429.42415-16-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Thomas Huth The unrealize functions of the various vhost-user devices are calling the corresponding vhost_*_set_status() functions with a status of 0 to shut down the device correctly. Now these vhost_*_set_status() functions all follow this scheme: bool should_start = virtio_device_should_start(vdev, status); if (vhost_dev_is_started(&vvc->vhost_dev) == should_start) { return; } if (should_start) { /* ... do the initialization stuff ... */ } else { /* ... do the cleanup stuff ... */ } The problem here is virtio_device_should_start(vdev, 0) currently always returns "true" since it internally only looks at vdev->started instead of looking at the "status" parameter. Thus once the device got started once, virtio_device_should_start() always returns true and thus the vhost_*_set_status() functions return early, without ever doing any clean-up when being called with status == 0. This causes e.g. problems when trying to hot-plug and hot-unplug a vhost user devices multiple times since the de-initialization step is completely skipped during the unplug operation. This bug has been introduced in commit 9f6bcfd99f ("hw/virtio: move vm_running check to virtio_device_started") which replaced should_start = status & VIRTIO_CONFIG_S_DRIVER_OK; with should_start = virtio_device_started(vdev, status); which later got replaced by virtio_device_should_start(). This blocked the possibility to set should_start to false in case the status flag VIRTIO_CONFIG_S_DRIVER_OK was not set. Fix it by adjusting the virtio_device_should_start() function to only consider the status flag instead of vdev->started. Since this function is only used in the various vhost_*_set_status() functions for exactly the same purpose, it should be fine to fix it in this central place there without any risk to change the behavior of other code. Fixes: 9f6bcfd99f ("hw/virtio: move vm_running check to virtio_device_started") Buglink: https://issues.redhat.com/browse/RHEL-40708 Signed-off-by: Thomas Huth Message-Id: <20240618121958.88673-1-thuth@redhat.com> Reviewed-by: Manos Pitsidianakis Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin (cherry picked from commit d72479b11797c28893e1e3fc565497a9cae5ca16) Signed-off-by: Michael Tokarev diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h index 7d5ffdc145..2eafad17b8 100644 --- a/include/hw/virtio/virtio.h +++ b/include/hw/virtio/virtio.h @@ -470,9 +470,9 @@ static inline bool virtio_device_started(VirtIODevice *vdev, uint8_t status) * @vdev - the VirtIO device * @status - the devices status bits * - * This is similar to virtio_device_started() but also encapsulates a - * check on the VM status which would prevent a device starting - * anyway. + * This is similar to virtio_device_started() but ignores vdev->started + * and also encapsulates a check on the VM status which would prevent a + * device from starting anyway. */ static inline bool virtio_device_should_start(VirtIODevice *vdev, uint8_t status) { @@ -480,7 +480,7 @@ static inline bool virtio_device_should_start(VirtIODevice *vdev, uint8_t status return false; } - return virtio_device_started(vdev, status); + return status & VIRTIO_CONFIG_S_DRIVER_OK; } static inline void virtio_set_started(VirtIODevice *vdev, bool started)