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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 B07D6C43387 for ; Mon, 7 Jan 2019 13:54:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 697262147C for ; Mon, 7 Jan 2019 13:54:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728718AbfAGNyL (ORCPT ); Mon, 7 Jan 2019 08:54:11 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:54442 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726589AbfAGNyK (ORCPT ); Mon, 7 Jan 2019 08:54:10 -0500 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id x07Ds4aW008107 for ; Mon, 7 Jan 2019 08:54:09 -0500 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 2pv7d19uy8-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 07 Jan 2019 08:54:06 -0500 Received: from localhost by e06smtp03.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) Mon, 7 Jan 2019 13:49:04 -0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x07Dn3IL63504638 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 7 Jan 2019 13:49:04 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D16F6AE045; Mon, 7 Jan 2019 13:49:03 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 70336AE04D; Mon, 7 Jan 2019 13:49:03 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.152.224.141]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 7 Jan 2019 13:49:03 +0000 (GMT) Subject: Re: [PATCH v3 1/3] virtio-balloon: tweak config_changed implementation To: Wei Wang , virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, mst@redhat.com, cohuck@redhat.com Cc: pbonzini@redhat.com, dgilbert@redhat.com, pasic@linux.ibm.com References: <1546844466-38079-1-git-send-email-wei.w.wang@intel.com> <1546844466-38079-2-git-send-email-wei.w.wang@intel.com> From: Christian Borntraeger 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: <1546844466-38079-2-git-send-email-wei.w.wang@intel.com> Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 19010713-0012-0000-0000-000002E350A2 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19010713-0013-0000-0000-0000211A59CA Message-Id: <4ea022d4-6b89-b481-5747-871e154dd21a@de.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-01-07_06:,, 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-1901070124 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07.01.2019 08:01, Wei Wang wrote: > virtio-ccw has deadlock issues with reading the config space inside the > interrupt context, so we tweak the virtballoon_changed implementation > by moving the config read operations into the related workqueue contexts. > The config_read_bitmap is used as a flag to the workqueue callbacks > about the related config fields that need to be read. > > The cmd_id_received is also renamed to cmd_id_received_cache, and > the value should be obtained via virtio_balloon_cmd_id_received. > > Reported-by: Christian Borntraeger > Signed-off-by: Wei Wang > Reviewed-by: Cornelia Huck > Reviewed-by: Halil Pasic Together with virtio_pci: use queue idx instead of array idx to set up the vq virtio: don't allocate vqs when names[i] = NULL Tested-by: Christian Borntraeger as already said, would be good to add cc stable (and a Fixes: tag) > --- > drivers/virtio/virtio_balloon.c | 98 +++++++++++++++++++++++++++-------------- > 1 file changed, 65 insertions(+), 33 deletions(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 728ecd1..fb12fe2 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -61,6 +61,10 @@ enum virtio_balloon_vq { > VIRTIO_BALLOON_VQ_MAX > }; > > +enum virtio_balloon_config_read { > + VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0, > +}; > + > struct virtio_balloon { > struct virtio_device *vdev; > struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; > @@ -77,14 +81,20 @@ struct virtio_balloon { > /* Prevent updating balloon when it is being canceled. */ > spinlock_t stop_update_lock; > bool stop_update; > + /* Bitmap to indicate if reading the related config fields are needed */ > + unsigned long config_read_bitmap; > > /* The list of allocated free pages, waiting to be given back to mm */ > struct list_head free_page_list; > spinlock_t free_page_list_lock; > /* The number of free page blocks on the above list */ > unsigned long num_free_page_blocks; > - /* The cmd id received from host */ > - u32 cmd_id_received; > + /* > + * The cmd id received from host. > + * Read it via virtio_balloon_cmd_id_received to get the latest value > + * sent from host. > + */ > + u32 cmd_id_received_cache; > /* The cmd id that is actively in use */ > __virtio32 cmd_id_active; > /* Buffer to store the stop sign */ > @@ -390,37 +400,31 @@ static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb, > return num_returned; > } > > +static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb) > +{ > + if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) > + return; > + > + /* No need to queue the work if the bit was already set. */ > + if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID, > + &vb->config_read_bitmap)) > + return; > + > + queue_work(vb->balloon_wq, &vb->report_free_page_work); > +} > + > static void virtballoon_changed(struct virtio_device *vdev) > { > struct virtio_balloon *vb = vdev->priv; > unsigned long flags; > - s64 diff = towards_target(vb); > - > - if (diff) { > - spin_lock_irqsave(&vb->stop_update_lock, flags); > - if (!vb->stop_update) > - queue_work(system_freezable_wq, > - &vb->update_balloon_size_work); > - spin_unlock_irqrestore(&vb->stop_update_lock, flags); > - } > > - if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { > - virtio_cread(vdev, struct virtio_balloon_config, > - free_page_report_cmd_id, &vb->cmd_id_received); > - if (vb->cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) { > - /* Pass ULONG_MAX to give back all the free pages */ > - return_free_pages_to_mm(vb, ULONG_MAX); > - } else if (vb->cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP && > - vb->cmd_id_received != > - virtio32_to_cpu(vdev, vb->cmd_id_active)) { > - spin_lock_irqsave(&vb->stop_update_lock, flags); > - if (!vb->stop_update) { > - queue_work(vb->balloon_wq, > - &vb->report_free_page_work); > - } > - spin_unlock_irqrestore(&vb->stop_update_lock, flags); > - } > + spin_lock_irqsave(&vb->stop_update_lock, flags); > + if (!vb->stop_update) { > + queue_work(system_freezable_wq, > + &vb->update_balloon_size_work); > + virtio_balloon_queue_free_page_work(vb); > } > + spin_unlock_irqrestore(&vb->stop_update_lock, flags); > } > > static void update_balloon_size(struct virtio_balloon *vb) > @@ -527,6 +531,17 @@ static int init_vqs(struct virtio_balloon *vb) > return 0; > } > > +static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb) > +{ > + if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID, > + &vb->config_read_bitmap)) > + virtio_cread(vb->vdev, struct virtio_balloon_config, > + free_page_report_cmd_id, > + &vb->cmd_id_received_cache); > + > + return vb->cmd_id_received_cache; > +} > + > static int send_cmd_id_start(struct virtio_balloon *vb) > { > struct scatterlist sg; > @@ -537,7 +552,8 @@ static int send_cmd_id_start(struct virtio_balloon *vb) > while (virtqueue_get_buf(vq, &unused)) > ; > > - vb->cmd_id_active = cpu_to_virtio32(vb->vdev, vb->cmd_id_received); > + vb->cmd_id_active = virtio32_to_cpu(vb->vdev, > + virtio_balloon_cmd_id_received(vb)); > sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active)); > err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL); > if (!err) > @@ -620,7 +636,8 @@ static int send_free_pages(struct virtio_balloon *vb) > * stop the reporting. > */ > cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active); > - if (cmd_id_active != vb->cmd_id_received) > + if (unlikely(cmd_id_active != > + virtio_balloon_cmd_id_received(vb))) > break; > > /* > @@ -637,11 +654,9 @@ static int send_free_pages(struct virtio_balloon *vb) > return 0; > } > > -static void report_free_page_func(struct work_struct *work) > +static void virtio_balloon_report_free_page(struct virtio_balloon *vb) > { > int err; > - struct virtio_balloon *vb = container_of(work, struct virtio_balloon, > - report_free_page_work); > struct device *dev = &vb->vdev->dev; > > /* Start by sending the received cmd id to host with an outbuf. */ > @@ -659,6 +674,23 @@ static void report_free_page_func(struct work_struct *work) > dev_err(dev, "Failed to send a stop id, err = %d\n", err); > } > > +static void report_free_page_func(struct work_struct *work) > +{ > + struct virtio_balloon *vb = container_of(work, struct virtio_balloon, > + report_free_page_work); > + u32 cmd_id_received; > + > + cmd_id_received = virtio_balloon_cmd_id_received(vb); > + if (cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) { > + /* Pass ULONG_MAX to give back all the free pages */ > + return_free_pages_to_mm(vb, ULONG_MAX); > + } else if (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP && > + cmd_id_received != > + virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) { > + virtio_balloon_report_free_page(vb); > + } > +} > + > #ifdef CONFIG_BALLOON_COMPACTION > /* > * virtballoon_migratepage - perform the balloon page migration on behalf of > @@ -885,7 +917,7 @@ static int virtballoon_probe(struct virtio_device *vdev) > goto out_del_vqs; > } > INIT_WORK(&vb->report_free_page_work, report_free_page_func); > - vb->cmd_id_received = VIRTIO_BALLOON_CMD_ID_STOP; > + vb->cmd_id_received_cache = 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, >