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 30CEBC36010 for ; Fri, 4 Apr 2025 14:29:43 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1u0i25-0005ms-6B; Fri, 04 Apr 2025 10:28:33 -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 1u0i20-0005h2-6c for qemu-devel@nongnu.org; Fri, 04 Apr 2025 10:28:29 -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 1u0i1x-0000mI-Kl for qemu-devel@nongnu.org; Fri, 04 Apr 2025 10:28:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743776904; 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=H6RnnYC3v9g45HLPJgt9FciXm16JPKf8o3J63kdDnBA=; b=Wbi+1jD7B7YJwp3WkH7uk9nGSBDC3YMtj3BLaKvdfqAhXnsyQEisxbjFh94/OPOawOphVr 8bliN5tKJzOUhkVCH960QsiuzZ7SYrfmudiiheCp/hDXTJtTRTlNOBtczWhpQ1cBHFLUay zeN4/glXwQ4OFhjoOZ+IoKNOArkbJns= Received: from mx-prod-mc-02.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-387-KVQuJiyFM3avwvo-m8aRhQ-1; Fri, 04 Apr 2025 10:28:19 -0400 X-MC-Unique: KVQuJiyFM3avwvo-m8aRhQ-1 X-Mimecast-MFC-AGG-ID: KVQuJiyFM3avwvo-m8aRhQ_1743776898 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9BD1019560B0; Fri, 4 Apr 2025 14:28:17 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.7]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 233993001D0E; Fri, 4 Apr 2025 14:28:15 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 8AC6E21E66C7; Fri, 04 Apr 2025 16:28:12 +0200 (CEST) From: Markus Armbruster To: Vladimir Sementsov-Ogievskiy Cc: mst@redhat.com, sgarzare@redhat.com, dave@treblig.org, eblake@redhat.com, pbonzini@redhat.com, berrange@redhat.com, eduardo@habkost.net, qemu-devel@nongnu.org, Denis Plotnikov Subject: Re: [PATCH v5] [for-10.1] virtio: add VIRTQUEUE_ERROR QAPI event In-Reply-To: <18763620-2bd9-47a6-a5d4-ff61663bae9a@yandex-team.ru> (Vladimir Sementsov-Ogievskiy's message of "Fri, 4 Apr 2025 13:26:42 +0300") References: <20250401170731.121336-1-vsementsov@yandex-team.ru> <878qogqv8u.fsf@pond.sub.org> <18763620-2bd9-47a6-a5d4-ff61663bae9a@yandex-team.ru> Date: Fri, 04 Apr 2025 16:28:12 +0200 Message-ID: <8734eongqr.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 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: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.028, 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_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: 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: > On 04.04.25 09:46, Markus Armbruster wrote: >> 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. >>> >>> Signed-off-by: Vladimir Sementsov-Ogievskiy >>> Reviewed-by: Denis Plotnikov >>> --- >>> >>> v5: resend, update version in QAPI to 10.1 >>> drop a-b by Markus (too much time passed, the context could >>> changed. Markus, is the patch still OK?) >> >> Happy to take another look :) >> >>> hw/virtio/vhost.c | 12 +++++++++--- >>> monitor/monitor.c | 10 ++++++++++ >>> qapi/qdev.json | 32 ++++++++++++++++++++++++++++++++ >>> 3 files changed, 51 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..1296a9207e 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 +500,10 @@ 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) { >>> + hash += g_str_hash(qdict_get_str(evstate->data, "device")); >> >> Isn't @device optional? Should you use @qom-path instead? > > Yes, I'm thinking about it too. This function and the next one together enable fine-grained event throttling. I figure the intent of your patch is to rate-limit this event per device. For that, you must use qom-path. If you wanted to rate-limit per virtqueue, you'd have to throw in @virtqueue. As is, you have a crash bugL g_str_hash() expects a non-null argument. > Maybe, drop the "device" field from the event at all, and keep only qom-path? Years passed since movement to use qom paths.. Possible justifications for having @device: consistency with other events, convenience for users. I can't judge the latter. > >> >>> + } >>> + >>> return hash; >>> } >>> >>> @@ -527,6 +532,11 @@ 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, "device"), >>> + qdict_get_str(evb->data, "device")); >> >> Likewise. >> >>> + } >>> + >>> return TRUE; >>> } >>> >>> diff --git a/qapi/qdev.json b/qapi/qdev.json >>> index 25cbcf977b..2d20f4777e 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: Vhost device reported failure through >>> +# through vring error fd. >> >> One "through" too many. >> >> I'm not quite sure I understand what you're trying to express. Is it >> "the vhost device has communicated failure via the vring error file >> descriptor"? > > Yes. Will use your wording. > >> >> I know next to nothing about vhost devices... >> >>> +# >>> +# Since: 10.1 >>> +## >>> +{ 'enum': 'VirtqueueError', >>> + 'data': [ 'vhost-vring-error' ] } >>> + >>> +## >>> +# @VIRTQUEUE_ERROR: >>> +# >>> +# Emitted when a device virtqueue fails in runtime. >> >> I think it's "at runtime". >> >> Can a device have more than one virtqueue? > > Yes. And event has "virtqueue": "int" for it. Got it, thanks! >>> +# >>> +# @device: the device's ID if it has one >>> +# >>> +# @path: the device's QOM path >> >> I agree with your follow-up: name it @qom-path. >> >>> +# >>> +# @virtqueue: virtqueue index >> >> Bear with me... What's a virtqueue index? > > sequence number of virtqueue of the vhost device Maybe something like "the index of the virtqueue that failed". >>> +# >>> +# @error: error identifier >>> +# >>> +# @description: human readable description >>> +# >>> +# Since: 10.1 >>> +## >>> +{ 'event': 'VIRTQUEUE_ERROR', >>> + 'data': { '*device': 'str', 'path': 'str', 'virtqueue': 'int', >>> + 'error': 'VirtqueueError', 'description': 'str'} } >>