From patchwork Mon Sep 10 14:56:15 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fam Zheng X-Patchwork-Id: 10594327 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7A9C8109C for ; Mon, 10 Sep 2018 15:06:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6B77327FC0 for ; Mon, 10 Sep 2018 15:06:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5F8AA281DB; Mon, 10 Sep 2018 15:06:14 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id F3FDE27FC0 for ; Mon, 10 Sep 2018 15:06:13 +0000 (UTC) Received: from localhost ([::1]:52162 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fzNlU-0000Mz-NG for patchwork-qemu-devel@patchwork.kernel.org; Mon, 10 Sep 2018 11:06:12 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55431) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fzNi6-0006Cy-6I for qemu-devel@nongnu.org; Mon, 10 Sep 2018 11:02:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fzNhw-00016s-3r for qemu-devel@nongnu.org; Mon, 10 Sep 2018 11:02:41 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:56052 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fzNcD-0004FM-5s; Mon, 10 Sep 2018 10:56:37 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C119987927; Mon, 10 Sep 2018 14:56:36 +0000 (UTC) Received: from lemon.usersys.redhat.com (ovpn-12-67.pek2.redhat.com [10.72.12.67]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9FA4DAB59B; Mon, 10 Sep 2018 14:56:33 +0000 (UTC) From: Fam Zheng To: qemu-devel@nongnu.org Date: Mon, 10 Sep 2018 22:56:15 +0800 Message-Id: <20180910145616.8598-2-famz@redhat.com> In-Reply-To: <20180910145616.8598-1-famz@redhat.com> References: <20180910145616.8598-1-famz@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Mon, 10 Sep 2018 14:56:36 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Mon, 10 Sep 2018 14:56:36 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'famz@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH 1/2] virtio: Return true from virtio_queue_empty if broken X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , qemu-block@nongnu.org, "Michael S. Tsirkin" , peterx@redhat.com, Stefan Hajnoczi , Paolo Bonzini Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Both virtio-blk and virtio-scsi use virtio_queue_empty() as the loop condition in VQ handlers (virtio_blk_handle_vq, virtio_scsi_handle_cmd_vq). When a device is marked broken in virtqueue_pop, for example if a vIOMMU address translation failed, we want to break out of the loop. This fixes a hanging problem when booting a CentOS 3.10.0-862.el7.x86_64 kernel with ATS enabled: $ qemu-system-x86_64 \ ... \ -device intel-iommu,intremap=on,caching-mode=on,eim=on,device-iotlb=on \ -device virtio-scsi-pci,iommu_platform=on,ats=on,id=scsi0,bus=pci.4,addr=0x0 The dead loop happens immediately when the kernel boots and initializes the device, where virtio_scsi_data_plane_handle_cmd will not return: > ... > #13 0x00005586602b7793 in virtio_scsi_handle_cmd_vq > #14 0x00005586602b8d66 in virtio_scsi_data_plane_handle_cmd > #15 0x00005586602ddab7 in virtio_queue_notify_aio_vq > #16 0x00005586602dfc9f in virtio_queue_host_notifier_aio_poll > #17 0x00005586607885da in run_poll_handlers_once > #18 0x000055866078880e in try_poll_mode > #19 0x00005586607888eb in aio_poll > #20 0x0000558660784561 in aio_wait_bh_oneshot > #21 0x00005586602b9582 in virtio_scsi_dataplane_stop > #22 0x00005586605a7110 in virtio_bus_stop_ioeventfd > #23 0x00005586605a9426 in virtio_pci_stop_ioeventfd > #24 0x00005586605ab808 in virtio_pci_common_write > #25 0x0000558660242396 in memory_region_write_accessor > #26 0x00005586602425ab in access_with_adjusted_size > #27 0x0000558660245281 in memory_region_dispatch_write > #28 0x00005586601e008e in flatview_write_continue > #29 0x00005586601e01d8 in flatview_write > #30 0x00005586601e04de in address_space_write > #31 0x00005586601e052f in address_space_rw > #32 0x00005586602607f2 in kvm_cpu_exec > #33 0x0000558660227148 in qemu_kvm_cpu_thread_fn > #34 0x000055866078bde7 in qemu_thread_start > #35 0x00007f5784906594 in start_thread > #36 0x00007f5784639e6f in clone With this patch, virtio_queue_empty will now return 1 as soon as the vdev is marked as broken, after a "virtio: zero sized buffers are not allowed" error. To be consistent, update virtio_queue_empty_rcu as well. Signed-off-by: Fam Zheng --- hw/virtio/virtio.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index d4e4d98b59..7a05c9e52c 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -358,6 +358,10 @@ int virtio_queue_ready(VirtQueue *vq) * Called within rcu_read_lock(). */ static int virtio_queue_empty_rcu(VirtQueue *vq) { + if (unlikely(vq->vdev->broken)) { + return 1; + } + if (unlikely(!vq->vring.avail)) { return 1; } @@ -373,6 +377,10 @@ int virtio_queue_empty(VirtQueue *vq) { bool empty; + if (unlikely(vq->vdev->broken)) { + return 1; + } + if (unlikely(!vq->vring.avail)) { return 1; }