From mboxrd@z Thu Jan 1 00:00:00 1970 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 5E677C36002 for ; Wed, 9 Apr 2025 10:50:11 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1u2SzM-0000Y6-Im; Wed, 09 Apr 2025 06:49:00 -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 1u2SzL-0000Xw-Ks for qemu-devel@nongnu.org; Wed, 09 Apr 2025 06:48:59 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1u2SzJ-0007UQ-NL for qemu-devel@nongnu.org; Wed, 09 Apr 2025 06:48:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744195735; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=bApCIjPDb7rE6jneUbjBXg2x2UuQ8rEQgogaE+eQ554=; b=GXAOITcjk3bGlOokI4lnn6r9Iwyk/N9FfE4mMPIO6C8x3hOL6lbVfxnjK9G09jJQYs5NR+ PMw2JAgZANREmlBD/QmVvb8z1PMqn/NwUVPQtPffCX6N7yK4csp4hH+Mrf/qxnWRGAhjV8 +DA3Mq0RDnKWTZlWfiJ6PahOJCnkt88= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-221-mgagX8wCOkKv6YUrlRAqMw-1; Wed, 09 Apr 2025 06:48:52 -0400 X-MC-Unique: mgagX8wCOkKv6YUrlRAqMw-1 X-Mimecast-MFC-AGG-ID: mgagX8wCOkKv6YUrlRAqMw_1744195731 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EC0211955BC5; Wed, 9 Apr 2025 10:48:50 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.7]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 29A1A1955BC1; Wed, 9 Apr 2025 10:48:49 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 9CAB021E675E; Wed, 09 Apr 2025 12:48:46 +0200 (CEST) From: Markus Armbruster To: Vladimir Sementsov-Ogievskiy Cc: qemu-devel@nongnu.org, mst@redhat.com, eblake@redhat.com, eduardo@habkost.net, berrange@redhat.com, pbonzini@redhat.com, dave@treblig.org, armbru@redhat.com, sgarzare@redhat.com, den-plotnikov@yandex-team.ru Subject: Re: [PATCH v6] [for-10.1] virtio: add VIRTQUEUE_ERROR QAPI event In-Reply-To: <20250409094758.58232-1-vsementsov@yandex-team.ru> (Vladimir Sementsov-Ogievskiy's message of "Wed, 9 Apr 2025 12:47:58 +0300") References: <20250409094758.58232-1-vsementsov@yandex-team.ru> Date: Wed, 09 Apr 2025 12:48:46 +0200 Message-ID: <87plhlbofl.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.845, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_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: 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 Vladimir Sementsov-Ogievskiy writes: > For now we only log the vhost device error, when virtqueue is actually > stopped. Let's add a QAPI event, which makes possible: > > - collect statistics of such errors > - make immediate actions: take core dumps or do some other debugging > - inform the user through a management API or UI, so that (s)he can > react somehow, e.g. reset the device driver in the guest or even > build up some automation to do so > > Note that basically every inconsistency discovered during virtqueue > processing results in a silent virtqueue stop. The guest then just > sees the requests getting stuck somewhere in the device for no visible > reason. This event provides a means to inform the management layer of > this situation in a timely fashion. > > The event could be reused for some other virtqueue problems (not only > for vhost devices) in future. For this it gets a generic name and > structure. > > We keep original VHOST_OPS_DEBUG(), to keep original debug output as is > here, it's not the only call to VHOST_OPS_DEBUG in the file. Likely should be tracepoints. Not this patch's problem, though. > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > > v6: rename path to qom-path, and improve throttling of the event > improve wording > > hw/virtio/vhost.c | 12 +++++++++--- > monitor/monitor.c | 14 ++++++++++++++ > qapi/qdev.json | 32 ++++++++++++++++++++++++++++++++ > 3 files changed, 55 insertions(+), 3 deletions(-) > > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c > index 6aa72fd434..0b205cef73 100644 > --- a/hw/virtio/vhost.c > +++ b/hw/virtio/vhost.c > @@ -15,6 +15,7 @@ > > #include "qemu/osdep.h" > #include "qapi/error.h" > +#include "qapi/qapi-events-qdev.h" > #include "hw/virtio/vhost.h" > #include "qemu/atomic.h" > #include "qemu/range.h" > @@ -1442,11 +1443,16 @@ static void vhost_virtqueue_error_notifier(EventNotifier *n) > struct vhost_virtqueue *vq = container_of(n, struct vhost_virtqueue, > error_notifier); > struct vhost_dev *dev = vq->dev; > - int index = vq - dev->vqs; > > if (event_notifier_test_and_clear(n) && dev->vdev) { > - VHOST_OPS_DEBUG(-EINVAL, "vhost vring error in virtqueue %d", > - dev->vq_index + index); > + int ind = vq - dev->vqs + dev->vq_index; > + DeviceState *ds = &dev->vdev->parent_obj; > + > + VHOST_OPS_DEBUG(-EINVAL, "vhost vring error in virtqueue %d", ind); > + qapi_event_send_virtqueue_error(ds->id, ds->canonical_path, ind, > + VIRTQUEUE_ERROR_VHOST_VRING_ERROR, > + "vhost reported failure through vring " > + "error fd"); > } > } > > diff --git a/monitor/monitor.c b/monitor/monitor.c > index c5a5d30877..11c8859703 100644 > --- a/monitor/monitor.c > +++ b/monitor/monitor.c > @@ -313,6 +313,7 @@ static MonitorQAPIEventConf monitor_qapi_event_conf[QAPI_EVENT__MAX] = { > [QAPI_EVENT_BALLOON_CHANGE] = { 1000 * SCALE_MS }, > [QAPI_EVENT_QUORUM_REPORT_BAD] = { 1000 * SCALE_MS }, > [QAPI_EVENT_QUORUM_FAILURE] = { 1000 * SCALE_MS }, > + [QAPI_EVENT_VIRTQUEUE_ERROR] = { 1000 * SCALE_MS }, > [QAPI_EVENT_VSERPORT_CHANGE] = { 1000 * SCALE_MS }, > [QAPI_EVENT_MEMORY_DEVICE_SIZE_CHANGE] = { 1000 * SCALE_MS }, > [QAPI_EVENT_HV_BALLOON_STATUS_REPORT] = { 1000 * SCALE_MS }, > @@ -499,6 +500,12 @@ static unsigned int qapi_event_throttle_hash(const void *key) > hash += g_str_hash(qdict_get_str(evstate->data, "qom-path")); > } > > + if (evstate->event == QAPI_EVENT_VIRTQUEUE_ERROR) { > + uint64_t virtqueue = qdict_get_int(evstate->data, "virtqueue"); > + hash += g_str_hash(qdict_get_str(evstate->data, "qom-path")) ^ > + g_int64_hash(&virtqueue); > + } > + > return hash; > } > > @@ -527,6 +534,13 @@ static gboolean qapi_event_throttle_equal(const void *a, const void *b) > qdict_get_str(evb->data, "qom-path")); > } > > + if (eva->event == QAPI_EVENT_VIRTQUEUE_ERROR) { > + return !strcmp(qdict_get_str(eva->data, "qom-path"), > + qdict_get_str(evb->data, "qom-path")) && > + (qdict_get_int(eva->data, "virtqueue") == > + qdict_get_int(evb->data, "virtqueue")); > + } > + > return TRUE; > } > Rate-limiting is now per virt queue. It was per device in previous revisions. Worth it? > diff --git a/qapi/qdev.json b/qapi/qdev.json > index 25cbcf977b..ddfae18761 100644 > --- a/qapi/qdev.json > +++ b/qapi/qdev.json > @@ -187,3 +187,35 @@ > { 'command': 'device-sync-config', > 'features': [ 'unstable' ], > 'data': {'id': 'str'} } > + > +## > +# @VirtqueueError: > +# > +# @vhost-vring-error: the vhost device has communicated failure via > +# the vring error file descriptor > +# > +# Since: 10.1 > +## > +{ 'enum': 'VirtqueueError', > + 'data': [ 'vhost-vring-error' ] } > + > +## > +# @VIRTQUEUE_ERROR: > +# > +# Emitted when a device virtqueue fails at runtime. > +# > +# @device: the device's ID if it has one > +# > +# @qom-path: the device's QOM path > +# > +# @virtqueue: the index of the virtqueue that failed > +# > +# @error: error identifier > +# > +# @description: human readable description > +# > +# Since: 10.1 > +## > +{ 'event': 'VIRTQUEUE_ERROR', > + 'data': { '*device': 'str', 'qom-path': 'str', 'virtqueue': 'int', > + 'error': 'VirtqueueError', 'description': 'str'} } Standard question for events: can a management application poll for the information as well? I might have asked this before, I don't remember. If you already answered it, feel free to point me to your answer. Why is this a standard question for events? Say, a management application wants to track the state of X. Two ways: poll the state with a query command that returns it, listen for events that report a change of X. Listening for an event is more efficient. However, if the management application connects to a QEMU instance, X could be anything, so it needs to poll once. Special case: the management application restarts for some reason.