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 X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F21CC43444 for ; Thu, 27 Dec 2018 12:17:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EDE95218FC for ; Thu, 27 Dec 2018 12:17:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731006AbeL0MRc (ORCPT ); Thu, 27 Dec 2018 07:17:32 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:35982 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730891AbeL0MRc (ORCPT ); Thu, 27 Dec 2018 07:17:32 -0500 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wBRC97Y5028047 for ; Thu, 27 Dec 2018 07:17:31 -0500 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2pmu9mfmnh-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 27 Dec 2018 07:17:31 -0500 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 27 Dec 2018 12:17:22 -0000 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id wBRCHLia34799844 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 27 Dec 2018 12:17:21 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1EE7B52050; Thu, 27 Dec 2018 12:17:21 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.152.224.141]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 6FDB752052; Thu, 27 Dec 2018 12:17:20 +0000 (GMT) Subject: Re: [PATCH v37 0/3] Virtio-balloon: support free page reporting From: Christian Borntraeger To: Wei Wang , virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mst@redhat.com, mhocko@kernel.org, akpm@linux-foundation.org, dgilbert@redhat.com Cc: torvalds@linux-foundation.org, pbonzini@redhat.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com, peterx@redhat.com, quintela@redhat.com, Halil Pasic , Cornelia Huck References: <1535333539-32420-1-git-send-email-wei.w.wang@intel.com> <0661b05a-d9d0-d374-44e8-2583463e94c2@de.ibm.com> Openpgp: preference=signencrypt Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18122712-0008-0000-0000-000002A6EF65 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18122712-0009-0000-0000-00002212F58E Message-Id: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-12-27_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1812270112 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27.12.2018 12:59, Christian Borntraeger wrote: > On 27.12.2018 12:31, Christian Borntraeger wrote: >> This patch triggers random crashes in the guest kernel on s390 early during boot. >> No migration and no setting of the balloon is involved. >> > > Adding Conny and Halil, > > As the QEMU provides no PAGE_HINT feature yet, this quick hack makes the > guest boot fine again: > > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 728ecd1eea305..aa2e1864c5736 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -492,7 +492,7 @@ static int init_vqs(struct virtio_balloon *vb) > callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; > } > > - err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, > + err = vb->vdev->config->find_vqs(vb->vdev, 3, //VIRTIO_BALLOON_VQ_MAX, > vqs, callbacks, names, NULL, NULL); > if (err) > return err; > > > To me it looks like that virtio_ccw_find_vqs will abort if any of the virtqueues > that it is been asked for does not exist (including the earlier ones). > This "hack" makes the random crashes go away, but the balloon interface itself does not work. (setting the value to anything will hang the guest). As patch 1 also modifies the main path, there seem to be additional issues, maybe endianess Looking at things like + vb->cmd_id_received = VIRTIO_BALLOON_CMD_ID_STOP; + vb->cmd_id_active = cpu_to_virtio32(vb->vdev, + VIRTIO_BALLOON_CMD_ID_STOP); + vb->cmd_id_stop = cpu_to_virtio32(vb->vdev, + VIRTIO_BALLOON_CMD_ID_STOP); Why is cmd_id_received not using cpu_to_virtio32?