From nobody Tue Feb 10 11:55:55 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1770061829843968.894087460919; Mon, 2 Feb 2026 11:50:29 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vmzt4-0000G8-1M; Mon, 02 Feb 2026 14:47:06 -0500 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 1vmzt2-0000Ew-2F; Mon, 02 Feb 2026 14:47:04 -0500 Received: from isrv.corpit.ru ([212.248.84.144]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vmzt0-0003Dy-Dm; Mon, 02 Feb 2026 14:47:03 -0500 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 2FCFD18509B; Mon, 02 Feb 2026 22:46:03 +0300 (MSK) Received: from think4mjt.tls.msk.ru (mjtthink.wg.tls.msk.ru [192.168.177.146]) by tsrv.corpit.ru (Postfix) with ESMTP id D7F7A35B27D; Mon, 02 Feb 2026 22:46:44 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Hanna Czenczek , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Michael Tokarev Subject: [Stable-10.0.8 09/69] vhost: Always initialize cached vring data Date: Mon, 2 Feb 2026 22:45:32 +0300 Message-ID: <20260202194638.939438-9-mjt@tls.msk.ru> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=212.248.84.144; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, 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: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1770061831233158500 From: Hanna Czenczek vhost_virtqueue_start() can exit early if the descriptor ring address is 0, assuming the virtqueue isn=E2=80=99t ready to start. In this case, all cached vring information (size, physical address, pointer) is left as-is. This is OK at first startup, when that info is still initialized to 0, but after a reset, it will retain old (outdated) information. vhost_virtqueue_start() must make sure these values are (re-)set properly before exiting. (When using an IOMMU, these outdated values can stall the device: vhost_dev_start() deliberately produces an IOMMU miss event for each used vring. If used_phys contains an outdated value, the resulting lookup may fail, forcing the device to be stopped.) Cc: qemu-stable@nongnu.org Signed-off-by: Hanna Czenczek Reviewed-by: Philippe Mathieu-Daud=C3=A9 Message-ID: <20251208113008.153249-1-hreitz@redhat.com> Signed-off-by: Philippe Mathieu-Daud=C3=A9 (cherry picked from commit 46228925edd53bb0569519538b94e10b85f9c001) Signed-off-by: Michael Tokarev diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index e72d991c55..971460eb2a 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -1245,7 +1245,7 @@ int vhost_virtqueue_start(struct vhost_dev *dev, BusState *qbus =3D BUS(qdev_get_parent_bus(DEVICE(vdev))); VirtioBusState *vbus =3D VIRTIO_BUS(qbus); VirtioBusClass *k =3D VIRTIO_BUS_GET_CLASS(vbus); - hwaddr s, l, a; + hwaddr l; int r; int vhost_vq_index =3D dev->vhost_ops->vhost_get_vq_index(dev, idx); struct vhost_vring_file file =3D { @@ -1256,8 +1256,17 @@ int vhost_virtqueue_start(struct vhost_dev *dev, }; struct VirtQueue *vvq =3D virtio_get_queue(vdev, idx); =20 - a =3D virtio_queue_get_desc_addr(vdev, idx); - if (a =3D=3D 0) { + vq->desc_size =3D virtio_queue_get_desc_size(vdev, idx); + vq->desc_phys =3D virtio_queue_get_desc_addr(vdev, idx); + vq->desc =3D NULL; + vq->avail_size =3D virtio_queue_get_avail_size(vdev, idx); + vq->avail_phys =3D virtio_queue_get_avail_addr(vdev, idx); + vq->avail =3D NULL; + vq->used_size =3D virtio_queue_get_used_size(vdev, idx); + vq->used_phys =3D virtio_queue_get_used_addr(vdev, idx); + vq->used =3D NULL; + + if (vq->desc_phys =3D=3D 0) { /* Queue might not be ready for start */ return 0; } @@ -1285,24 +1294,23 @@ int vhost_virtqueue_start(struct vhost_dev *dev, } } =20 - vq->desc_size =3D s =3D l =3D virtio_queue_get_desc_size(vdev, idx); - vq->desc_phys =3D a; - vq->desc =3D vhost_memory_map(dev, a, &l, false); - if (!vq->desc || l !=3D s) { + l =3D vq->desc_size; + vq->desc =3D vhost_memory_map(dev, vq->desc_phys, &l, false); + if (!vq->desc || l !=3D vq->desc_size) { r =3D -ENOMEM; goto fail_alloc_desc; } - vq->avail_size =3D s =3D l =3D virtio_queue_get_avail_size(vdev, idx); - vq->avail_phys =3D a =3D virtio_queue_get_avail_addr(vdev, idx); - vq->avail =3D vhost_memory_map(dev, a, &l, false); - if (!vq->avail || l !=3D s) { + + l =3D vq->avail_size; + vq->avail =3D vhost_memory_map(dev, vq->avail_phys, &l, false); + if (!vq->avail || l !=3D vq->avail_size) { r =3D -ENOMEM; goto fail_alloc_avail; } - vq->used_size =3D s =3D l =3D virtio_queue_get_used_size(vdev, idx); - vq->used_phys =3D a =3D virtio_queue_get_used_addr(vdev, idx); - vq->used =3D vhost_memory_map(dev, a, &l, true); - if (!vq->used || l !=3D s) { + + l =3D vq->used_size; + vq->used =3D vhost_memory_map(dev, vq->used_phys, &l, true); + if (!vq->used || l !=3D vq->used_size) { r =3D -ENOMEM; goto fail_alloc_used; } --=20 2.47.3