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 6A072D21265 for ; Thu, 17 Oct 2024 09:17:46 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t1MdZ-0007iM-Tf; Thu, 17 Oct 2024 05:17:41 -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 1t1MdX-0007iA-VF for qemu-devel@nongnu.org; Thu, 17 Oct 2024 05:17:40 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t1MdW-0003he-23 for qemu-devel@nongnu.org; Thu, 17 Oct 2024 05:17:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1729156657; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=3aR5/6oW8HF/UBo9q99JIkpNfjS/sm/Ou2ZYxlrIT3w=; b=ZX8oLiuTUwDGcjtWrz165Nxhd8JedqHRguyFJSS+/byUhHR5mkdo869m1WQP2R0ZhqNplz K4If5SASBfXhuZYKib6PmR00/+w70/5d2bALAmf0XNRyQJS8mTvnl3XZO5vPUBgXtfbXMP lvDShBQOTSSY1dFrOyGZCeqarLeOaJE= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-472-ZM4RxZ1uOUy_TQzz0RnP5w-1; Thu, 17 Oct 2024 05:17:35 -0400 X-MC-Unique: ZM4RxZ1uOUy_TQzz0RnP5w-1 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-37d67f4bf98so395100f8f.1 for ; Thu, 17 Oct 2024 02:17:35 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729156654; x=1729761454; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=3aR5/6oW8HF/UBo9q99JIkpNfjS/sm/Ou2ZYxlrIT3w=; b=KusEuU3UKSnmwwXetgpga7P1eH15jXepAJe/idaqQeVnfjjBXPgKYRGa6No+F2tmMi YXCUpcyyM/xUoZLtHxIG7Te9rlBIgrgcIvXIeRJyeCkza7Dmzc2lwaU4Tw5KTCSrIbKG G/8fLKjrF3a4PBYUk9L8oHLMRojBN/HsWg+oLzznmFYGI6ERngNvLQX9iGziDsebIKve Pja+RJXJrHwvH4K3zAWE0qDat5Hzqj6GQ8S0gY3WgAcjbaN+KoLZC7wMNFbAInNFoEI3 FedJgxXzDhqZ1TTkUE46kHfYtlgu2HFTzSv7eQ1Xg4JFCqKlQJudrlAObgQwZNWGccz3 djvA== X-Gm-Message-State: AOJu0YwgGXjnKUooXkA8d06h8sqYPlqFtOzmfCbcH85FyGkVhIt5DQiV SZc+3kdbgsiL8EgO04MsAvUUNKc8gGLKtw2L+sP4F62HePzLcVrGF/4aMJ9Syucnj+J6zZy1/1j v+GWNVhqq20FQ+wezAaVweu7xhBgyPEkAuNSKBbUw8i8IGBeltjLTMKj3sEfQ X-Received: by 2002:adf:e707:0:b0:37c:cdb6:6a9e with SMTP id ffacd0b85a97d-37d86ba4447mr4244683f8f.9.1729156654027; Thu, 17 Oct 2024 02:17:34 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEaWXjDyFvW17JFq/7nEyYTzqDmOXkMdyEWOFhaD3v3NxKWhHFKZFmuLwzLgD8xP4byvSOErw== X-Received: by 2002:adf:e707:0:b0:37c:cdb6:6a9e with SMTP id ffacd0b85a97d-37d86ba4447mr4244669f8f.9.1729156653565; Thu, 17 Oct 2024 02:17:33 -0700 (PDT) Received: from ?IPV6:2a01:e0a:e10:ef90:4c84:58cb:a1ef:8b78? ([2a01:e0a:e10:ef90:4c84:58cb:a1ef:8b78]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-37d7fbf8567sm6651207f8f.76.2024.10.17.02.17.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Oct 2024 02:17:33 -0700 (PDT) Message-ID: Date: Thu, 17 Oct 2024 11:17:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PULL 08/20] virtio-net: Add only one queue pair when realizing To: Akihiko Odaki , Jason Wang Cc: qemu-devel@nongnu.org, "Michael S. Tsirkin" References: <20240604073755.1859-1-jasowang@redhat.com> <20240604073755.1859-9-jasowang@redhat.com> <14bcc2cf-f934-4aa3-8cab-21803a930adc@redhat.com> <60169858-3930-4490-b42d-d04117ab9abd@daynix.com> Content-Language: en-US From: Laurent Vivier Autocrypt: addr=lvivier@redhat.com; keydata= xsFNBFYFJhkBEAC2me7w2+RizYOKZM+vZCx69GTewOwqzHrrHSG07MUAxJ6AY29/+HYf6EY2 WoeuLWDmXE7A3oJoIsRecD6BXHTb0OYS20lS608anr3B0xn5g0BX7es9Mw+hV/pL+63EOCVm SUVTEQwbGQN62guOKnJJJfphbbv82glIC/Ei4Ky8BwZkUuXd7d5NFJKC9/GDrbWdj75cDNQx UZ9XXbXEKY9MHX83Uy7JFoiFDMOVHn55HnncflUncO0zDzY7CxFeQFwYRbsCXOUL9yBtqLer Ky8/yjBskIlNrp0uQSt9LMoMsdSjYLYhvk1StsNPg74+s4u0Q6z45+l8RAsgLw5OLtTa+ePM JyS7OIGNYxAX6eZk1+91a6tnqfyPcMbduxyBaYXn94HUG162BeuyBkbNoIDkB7pCByed1A7q q9/FbuTDwgVGVLYthYSfTtN0Y60OgNkWCMtFwKxRaXt1WFA5ceqinN/XkgA+vf2Ch72zBkJL RBIhfOPFv5f2Hkkj0MvsUXpOWaOjatiu0fpPo6Hw14UEpywke1zN4NKubApQOlNKZZC4hu6/ 8pv2t4HRi7s0K88jQYBRPObjrN5+owtI51xMaYzvPitHQ2053LmgsOdN9EKOqZeHAYG2SmRW LOxYWKX14YkZI5j/TXfKlTpwSMvXho+efN4kgFvFmP6WT+tPnwARAQABzSNMYXVyZW50IFZp dmllciA8bHZpdmllckByZWRoYXQuY29tPsLBeAQTAQIAIgUCVgVQgAIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQ8ww4vT8vvjwpgg//fSGy0Rs/t8cPFuzoY1cex4limJQfReLr SJXCANg9NOWy/bFK5wunj+h/RCFxIFhZcyXveurkBwYikDPUrBoBRoOJY/BHK0iZo7/WQkur 6H5losVZtrotmKOGnP/lJYZ3H6OWvXzdz8LL5hb3TvGOP68K8Bn8UsIaZJoeiKhaNR0sOJyI YYbgFQPWMHfVwHD/U+/gqRhD7apVysxv5by/pKDln1I5v0cRRH6hd8M8oXgKhF2+rAOL7gvh jEHSSWKUlMjC7YwwjSZmUkL+TQyE18e2XBk85X8Da3FznrLiHZFHQ/NzETYxRjnOzD7/kOVy gKD/o7asyWQVU65mh/ECrtjfhtCBSYmIIVkopoLaVJ/kEbVJQegT2P6NgERC/31kmTF69vn8 uQyW11Hk8tyubicByL3/XVBrq4jZdJW3cePNJbTNaT0d/bjMg5zCWHbMErUib2Nellnbg6bc 2HLDe0NLVPuRZhHUHM9hO/JNnHfvgiRQDh6loNOUnm9Iw2YiVgZNnT4soUehMZ7au8PwSl4I KYE4ulJ8RRiydN7fES3IZWmOPlyskp1QMQBD/w16o+lEtY6HSFEzsK3o0vuBRBVp2WKnssVH qeeV01ZHw0bvWKjxVNOksP98eJfWLfV9l9e7s6TaAeySKRRubtJ+21PRuYAxKsaueBfUE7ZT 7zfOwU0EVgUmGQEQALxSQRbl/QOnmssVDxWhHM5TGxl7oLNJms2zmBpcmlrIsn8nNz0rRyxT 460k2niaTwowSRK8KWVDeAW6ZAaWiYjLlTunoKwvF8vP3JyWpBz0diTxL5o+xpvy/Q6YU3BN efdq8Vy3rFsxgW7mMSrI/CxJ667y8ot5DVugeS2NyHfmZlPGE0Nsy7hlebS4liisXOrN3jFz asKyUws3VXek4V65lHwB23BVzsnFMn/bw/rPliqXGcwl8CoJu8dSyrCcd1Ibs0/Inq9S9+t0 VmWiQWfQkz4rvEeTQkp/VfgZ6z98JRW7S6l6eophoWs0/ZyRfOm+QVSqRfFZdxdP2PlGeIFM C3fXJgygXJkFPyWkVElr76JTbtSHsGWbt6xUlYHKXWo+xf9WgtLeby3cfSkEchACrxDrQpj+ Jt/JFP+q997dybkyZ5IoHWuPkn7uZGBrKIHmBunTco1+cKSuRiSCYpBIXZMHCzPgVDjk4viP brV9NwRkmaOxVvye0vctJeWvJ6KA7NoAURplIGCqkCRwg0MmLrfoZnK/gRqVJ/f6adhU1oo6 z4p2/z3PemA0C0ANatgHgBb90cd16AUxpdEQmOCmdNnNJF/3Zt3inzF+NFzHoM5Vwq6rc1JP jfC3oqRLJzqAEHBDjQFlqNR3IFCIAo4SYQRBdAHBCzkM4rWyRhuVABEBAAHCwV8EGAECAAkF AlYFJhkCGwwACgkQ8ww4vT8vvjwg9w//VQrcnVg3TsjEybxDEUBm8dBmnKqcnTBFmxN5FFtI WlEuY8+YMiWRykd8Ln9RJ/98/ghABHz9TN8TRo2b6WimV64FmlVn17Ri6FgFU3xNt9TTEChq AcNg88eYryKsYpFwegGpwUlaUaaGh1m9OrTzcQy+klVfZWaVJ9Nw0keoGRGb8j4XjVpL8+2x OhXKrM1fzzb8JtAuSbuzZSQPDwQEI5CKKxp7zf76J21YeRrEW4WDznPyVcDTa+tz++q2S/Bp P4W98bXCBIuQgs2m+OflERv5c3Ojldp04/S4NEjXEYRWdiCxN7ca5iPml5gLtuvhJMSy36gl U6IW9kn30IWuSoBpTkgV7rLUEhh9Ms82VWW/h2TxL8enfx40PrfbDtWwqRID3WY8jLrjKfTd R3LW8BnUDNkG+c4FzvvGUs8AvuqxxyHbXAfDx9o/jXfPHVRmJVhSmd+hC3mcQ+4iX5bBPBPM oDqSoLt5w9GoQQ6gDVP2ZjTWqwSRMLzNr37rJjZ1pt0DCMMTbiYIUcrhX8eveCJtY7NGWNyx FCRkhxRuGcpwPmRVDwOl39MB3iTsRighiMnijkbLXiKoJ5CDVvX5yicNqYJPKh5MFXN1bvsB kmYiStMRbrD0HoY1kx5/VozBtc70OU0EB8Wrv9hZD+Ofp0T3KOr1RUHvCZoLURfFhSQ= In-Reply-To: <60169858-3930-4490-b42d-d04117ab9abd@daynix.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=lvivier@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.038, 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_H3=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 On 17/10/2024 11:07, Akihiko Odaki wrote: > On 2024/10/17 16:32, Laurent Vivier wrote: >> On 17/10/2024 08:59, Jason Wang wrote: >>> On Mon, Oct 14, 2024 at 11:16 PM Laurent Vivier wrote: >>>> >>>> On 14/10/2024 10:30, Laurent Vivier wrote: >>>>> Hi Akihiko, >>>>> >>>>> On 04/06/2024 09:37, Jason Wang wrote: >>>>>> From: Akihiko Odaki >>>>>> >>>>>> Multiqueue usage is not negotiated yet when realizing. If more than >>>>>> one queue is added and the guest never requests to enable multiqueue, >>>>>> the extra queues will not be deleted when unrealizing and leak. >>>>>> >>>>>> Fixes: f9d6dbf0bf6e ("virtio-net: remove virtio queues if the guest doesn't support >>>>>> multiqueue") >>>>>> Signed-off-by: Akihiko Odaki >>>>>> Signed-off-by: Jason Wang >>>>>> --- >>>>>>    hw/net/virtio-net.c | 4 +--- >>>>>>    1 file changed, 1 insertion(+), 3 deletions(-) >>>>>> >>>>>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c >>>>>> index 3cee2ef3ac..a8db8bfd9c 100644 >>>>>> --- a/hw/net/virtio-net.c >>>>>> +++ b/hw/net/virtio-net.c >>>>>> @@ -3743,9 +3743,7 @@ static void virtio_net_device_realize(DeviceState *dev, Error >>>>>> **errp) >>>>>>        n->net_conf.tx_queue_size = MIN(virtio_net_max_tx_queue_size(n), >>>>>>                                        n->net_conf.tx_queue_size); >>>>>> -    for (i = 0; i < n->max_queue_pairs; i++) { >>>>>> -        virtio_net_add_queue(n, i); >>>>>> -    } >>>>>> +    virtio_net_add_queue(n, 0); >>>>>>        n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl); >>>>>>        qemu_macaddr_default_if_unset(&n->nic_conf.macaddr); >>>>> >>>>> This change breaks virtio net migration when multiqueue is enabled. >>>>> >>>>> I think this is because virtqueues are half initialized after migration : they are >>>>> initialized on guest side (kernel is using them) but not on QEMU side (realized has only >>>>> initialized one). After migration, they are not initialized by the call to >>>>> virtio_net_set_multiqueue() from virtio_net_set_features() because >>>>> virtio_get_num_queues() >>>>> reports already n->max_queue_pairs as this value is coming from the source guest memory. >>>>> >>>>> I don't think we have a way to half-initialize a virtqueue (to initialize them only on >>>>> QEMU side as they are already initialized on kernel side). >>>>> >>>>> I think this change should be reverted to fix the migration issue. >>>>> >>>> >>>> Moreover, if I look in the code of virtio_load() and virtio_add_queue() we can guess it's >>>> not correct to migrate a virtqueue that is not initialized on the destination side >>>> because >>>> fields like 'vdev->vq[i].handle_output' or 'vdev->vq[i].used_elems' cannot be initialized >>>> by virtio_load() and neither by virtio_add_queue() after virtio_load() as fields like >>>> 'vring.num' are already initialized by virtio_load(). >>>> >>>> For instance, in virtio_load() we set: >>>> >>>>       for (i = 0; i < num; i++) { >>>>           vdev->vq[i].vring.num = qemu_get_be32(f); >>>> >>>> and in virtio_add_queue() we search for the firt available queue to add with: >>>> >>>>       for (i = 0; i < VIRTIO_QUEUE_MAX; i++) { >>>>           if (vdev->vq[i].vring.num == 0) >>>>               break; >>>>       } >>>> >>>> So virtio_add_queue() cannot be used to set: >>>> >>>>       vdev->vq[i].handle_output = handle_output; >>>>       vdev->vq[i].used_elems = g_new0(VirtQueueElement, queue_size); >>>> >>>> Moreover it would overwrite fields already set by virtio_load(): >>>> >>>>       vdev->vq[i].vring.num = queue_size; >>>>       vdev->vq[i].vring.align = VIRTIO_PCI_VRING_ALIGN; >>>> >>>> It also explains why virtio_net_change_num_queue_pairs() (indirectly called by >>>> virtio_net_set_features()) doesn't update the queue pair numbers: vring.num is already >>>> set >>>> so it thinks there is no more queues to add. >>>> >>>> Thanks, >>>> LAurent >>>> >>> >>> I agree. >>> >>> Laurent, would you like to send a patch to revert this? >>> >> >> Yes. I will also try to fix the leak in unrealize that the patch wanted to fix initially. > > I wrote a fix so I will submit it once internal testing is done. You can see the change at: > https://gitlab.com/akihiko.odaki/qemu-kvm/-/commit/22161221aa2d2031d7ad1be7701852083aa9109a It works fine for me but I don't know if it's a good idea to add queues while the state is loading. Jason, let me know which solution you prefer (revert or pre_load_queues helper). CC'ing MST Thanks, Laurent