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 953A7C43387 for ; Fri, 28 Dec 2018 06:36:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6A062208E4 for ; Fri, 28 Dec 2018 06:36:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729043AbeL1GgY (ORCPT ); Fri, 28 Dec 2018 01:36:24 -0500 Received: from mga12.intel.com ([192.55.52.136]:32082 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725929AbeL1GgX (ORCPT ); Fri, 28 Dec 2018 01:36:23 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Dec 2018 22:36:23 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,408,1539673200"; d="scan'208";a="131208853" Received: from unknown (HELO [10.239.13.114]) ([10.239.13.114]) by fmsmga004.fm.intel.com with ESMTP; 27 Dec 2018 22:36:20 -0800 Message-ID: <5C25C5A5.4080706@intel.com> Date: Fri, 28 Dec 2018 14:41:41 +0800 From: Wei Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Christian Borntraeger , 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 Subject: Re: [PATCH v37 0/3] Virtio-balloon: support free page reporting References: <1535333539-32420-1-git-send-email-wei.w.wang@intel.com> <0661b05a-d9d0-d374-44e8-2583463e94c2@de.ibm.com> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/27/2018 08:17 PM, Christian Borntraeger wrote: > > 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? > That conversion is only needed when we need to send the value to the device. cmd_id_received doesn't need to be sent to the device. Best, Wei