From patchwork Mon Jan 7 07:01:04 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Wang, Wei W" X-Patchwork-Id: 10750073 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A94CC91E for ; Mon, 7 Jan 2019 07:36:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 96EA028567 for ; Mon, 7 Jan 2019 07:36:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8AF3A2899B; Mon, 7 Jan 2019 07:36:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id ECDFF28567 for ; Mon, 7 Jan 2019 07:36:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726574AbfAGHgL (ORCPT ); Mon, 7 Jan 2019 02:36:11 -0500 Received: from mga01.intel.com ([192.55.52.88]:52919 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725306AbfAGHgL (ORCPT ); Mon, 7 Jan 2019 02:36:11 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Jan 2019 23:36:10 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,450,1539673200"; d="scan'208";a="107800026" Received: from devel-ww.sh.intel.com ([10.239.48.119]) by orsmga008.jf.intel.com with ESMTP; 06 Jan 2019 23:36:08 -0800 From: Wei Wang To: 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: borntraeger@de.ibm.com, pbonzini@redhat.com, dgilbert@redhat.com, wei.w.wang@intel.com, pasic@linux.ibm.com Subject: [PATCH v3 1/3] virtio-balloon: tweak config_changed implementation Date: Mon, 7 Jan 2019 15:01:04 +0800 Message-Id: <1546844466-38079-2-git-send-email-wei.w.wang@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1546844466-38079-1-git-send-email-wei.w.wang@intel.com> References: <1546844466-38079-1-git-send-email-wei.w.wang@intel.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 Tested-by: Christian Borntraeger --- 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,