From patchwork Sat Aug 27 17:10:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Tian, Kevin" X-Patchwork-Id: 12956951 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A25A3C0502F for ; Sat, 27 Aug 2022 09:52:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345389AbiH0JwQ (ORCPT ); Sat, 27 Aug 2022 05:52:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345293AbiH0Jvt (ORCPT ); Sat, 27 Aug 2022 05:51:49 -0400 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE3AAAB435; Sat, 27 Aug 2022 02:51:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661593900; x=1693129900; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=FJZtx2DAL5tyUpLeMYSIIC/i025+oTLApzGlLG5VPEg=; b=eMBImm+tu9LAthU/ZI0am3YIssx6t7TCrMdNCZRuXfIP85rHvXkwF3Ll +gD5Bl4vHd0epPclMecr7HhOi4YWBR4p9vfmIXS2ulzx1aizHvvyP/NUU ViEwkrSS8oReTqsv5gHjCYk3iuEBMOgNYWAF47/DqW3k8mbbAf2pOvEkY dmDzhqM8iWVIPdGZG2bin+K4PC5x//ynIbnjZanUn5J/kQADrUAi4ObhT 8sZhDtURY1ViRr/5POz0cz6TVwZH1bUU6eBFrH1O8SQnj/3cvXR+0r+Sr Hb1BxSL4pI2IXOZa4o2b+bUH2sh6Qc95uCZ87V/UZ76ZbmMhZUKXAd9jN g==; X-IronPort-AV: E=McAfee;i="6500,9779,10451"; a="277666470" X-IronPort-AV: E=Sophos;i="5.93,267,1654585200"; d="scan'208";a="277666470" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Aug 2022 02:51:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,267,1654585200"; d="scan'208";a="640354028" Received: from sqa-gate.sh.intel.com (HELO michael.clx.dev.tsp.org) ([10.239.48.212]) by orsmga008.jf.intel.com with ESMTP; 27 Aug 2022 02:51:31 -0700 From: Kevin Tian To: Zhenyu Wang , Zhi Wang , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Daniel Vetter , Eric Farman , Matthew Rosato , Halil Pasic , Vineeth Vijayan , Peter Oberparleiter , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Tony Krowiak , Jason Herne , Harald Freudenberger , Diana Craciun , Alex Williamson , Cornelia Huck , Longfang Liu , Shameer Kolothum , Jason Gunthorpe , Yishai Hadas , Kevin Tian , Eric Auger , Kirti Wankhede , Leon Romanovsky , Abhishek Sahu , intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org Cc: Yi Liu Subject: [PATCH 13/15] vfio/ccw: Use the new device life cycle helpers Date: Sun, 28 Aug 2022 01:10:35 +0800 Message-Id: <20220827171037.30297-14-kevin.tian@intel.com> X-Mailer: git-send-email 2.21.3 In-Reply-To: <20220827171037.30297-1-kevin.tian@intel.com> References: <20220827171037.30297-1-kevin.tian@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org ccw is the only exception which cannot use vfio_alloc_device() because its private device structure is designed to serve both mdev and parent. Life cycle of the parent is managed by css_driver so vfio_ccw_private must be allocated/freed in css_driver probe/remove path instead of conforming to vfio core life cycle for mdev. Given that use a wait/completion scheme so the mdev remove path waits after vfio_put_device() until receiving a completion notification from @release. The completion indicates that all active references on vfio_device have been released. After that point although free of vfio_ccw_private is delayed to css_driver it's at least guaranteed to have no parallel reference on released vfio device part from other code paths. memset() in @probe is removed. vfio_device is either alreary cleared when probed for the first time or cleared in @release from last probe. The right fix is to introduce separate structures for mdev and parent, but this won't happen in short term per prior discussions. Remove vfio_init/uninit_group_dev() as no user now. Signed-off-by: Kevin Tian --- drivers/s390/cio/vfio_ccw_ops.c | 52 +++++++++++++++++++++++++---- drivers/s390/cio/vfio_ccw_private.h | 3 ++ drivers/vfio/vfio_main.c | 27 +++------------ include/linux/vfio.h | 3 -- 4 files changed, 53 insertions(+), 32 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c index 4a806a2273b5..9f8486c0d3d3 100644 --- a/drivers/s390/cio/vfio_ccw_ops.c +++ b/drivers/s390/cio/vfio_ccw_ops.c @@ -87,6 +87,15 @@ static struct attribute_group *mdev_type_groups[] = { NULL, }; +static int vfio_ccw_mdev_init_dev(struct vfio_device *vdev) +{ + struct vfio_ccw_private *private = + container_of(vdev, struct vfio_ccw_private, vdev); + + init_completion(&private->release_comp); + return 0; +} + static int vfio_ccw_mdev_probe(struct mdev_device *mdev) { struct vfio_ccw_private *private = dev_get_drvdata(mdev->dev.parent); @@ -98,9 +107,9 @@ static int vfio_ccw_mdev_probe(struct mdev_device *mdev) if (atomic_dec_if_positive(&private->avail) < 0) return -EPERM; - memset(&private->vdev, 0, sizeof(private->vdev)); - vfio_init_group_dev(&private->vdev, &mdev->dev, - &vfio_ccw_dev_ops); + ret = vfio_init_device(&private->vdev, &mdev->dev, &vfio_ccw_dev_ops); + if (ret) + return ret; VFIO_CCW_MSG_EVENT(2, "sch %x.%x.%04x: create\n", private->sch->schid.cssid, @@ -109,16 +118,33 @@ static int vfio_ccw_mdev_probe(struct mdev_device *mdev) ret = vfio_register_emulated_iommu_dev(&private->vdev); if (ret) - goto err_atomic; + goto err_put_vdev; dev_set_drvdata(&mdev->dev, private); return 0; -err_atomic: - vfio_uninit_group_dev(&private->vdev); +err_put_vdev: + vfio_put_device(&private->vdev); atomic_inc(&private->avail); return ret; } +static void vfio_ccw_mdev_release_dev(struct vfio_device *vdev) +{ + struct vfio_ccw_private *private = + container_of(vdev, struct vfio_ccw_private, vdev); + + /* + * We cannot free vfio_ccw_private here because it includes + * parent info which must be free'ed by css driver. + * + * Use a workaround by memset'ing the core device part and + * then notifying the remove path that all active references + * to this device have been released. + */ + memset(vdev, 0, sizeof(*vdev)); + complete(&private->release_comp); +} + static void vfio_ccw_mdev_remove(struct mdev_device *mdev) { struct vfio_ccw_private *private = dev_get_drvdata(mdev->dev.parent); @@ -130,7 +156,17 @@ static void vfio_ccw_mdev_remove(struct mdev_device *mdev) vfio_unregister_group_dev(&private->vdev); - vfio_uninit_group_dev(&private->vdev); + vfio_put_device(&private->vdev); + /* + * Wait for all active references on mdev are released so it + * is safe to defer kfree() to a later point. + * + * TODO: the clean fix is to split parent/mdev info from ccw + * private structure so each can be managed in its own life + * cycle. + */ + wait_for_completion(&private->release_comp); + atomic_inc(&private->avail); } @@ -592,6 +628,8 @@ static void vfio_ccw_mdev_request(struct vfio_device *vdev, unsigned int count) } static const struct vfio_device_ops vfio_ccw_dev_ops = { + .init = vfio_ccw_mdev_init_dev, + .release = vfio_ccw_mdev_release_dev, .open_device = vfio_ccw_mdev_open_device, .close_device = vfio_ccw_mdev_close_device, .read = vfio_ccw_mdev_read, diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h index cd24b7fada91..63d9202b29c7 100644 --- a/drivers/s390/cio/vfio_ccw_private.h +++ b/drivers/s390/cio/vfio_ccw_private.h @@ -88,6 +88,7 @@ struct vfio_ccw_crw { * @req_trigger: eventfd ctx for signaling userspace to return device * @io_work: work for deferral process of I/O handling * @crw_work: work for deferral process of CRW handling + * @release_comp: synchronization helper for vfio device release */ struct vfio_ccw_private { struct vfio_device vdev; @@ -113,6 +114,8 @@ struct vfio_ccw_private { struct eventfd_ctx *req_trigger; struct work_struct io_work; struct work_struct crw_work; + + struct completion release_comp; } __aligned(8); int vfio_ccw_sch_quiesce(struct subchannel *sch); diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index 9485da17f2e6..15a612153c13 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -482,21 +482,6 @@ static struct vfio_device *vfio_group_get_device(struct vfio_group *group, /* * VFIO driver API */ -void vfio_init_group_dev(struct vfio_device *device, struct device *dev, - const struct vfio_device_ops *ops) -{ - init_completion(&device->comp); - device->dev = dev; - device->ops = ops; -} -EXPORT_SYMBOL_GPL(vfio_init_group_dev); - -void vfio_uninit_group_dev(struct vfio_device *device) -{ - vfio_release_device_set(device); -} -EXPORT_SYMBOL_GPL(vfio_uninit_group_dev); - /* * Alloc and initialize vfio_device so it can be registered to vfio * core. @@ -543,20 +528,18 @@ int vfio_init_device(struct vfio_device *device, struct device *dev, { int ret; - vfio_init_group_dev(device, dev, ops); + init_completion(&device->comp); + device->dev = dev; + device->ops = ops; if (ops->init) { ret = ops->init(device); if (ret) - goto out_uninit; + return ret; } kref_init(&device->kref); return 0; - -out_uninit: - vfio_uninit_group_dev(device); - return ret; } EXPORT_SYMBOL_GPL(vfio_init_device); @@ -577,7 +560,7 @@ void vfio_device_release(struct kref *kref) struct vfio_device *device = container_of(kref, struct vfio_device, kref); - vfio_uninit_group_dev(device); + vfio_release_device_set(device); /* * kvfree() cannot be done here due to a life cycle mess in diff --git a/include/linux/vfio.h b/include/linux/vfio.h index b0928a81b45a..a36a65b966b5 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -160,9 +160,6 @@ static inline void vfio_put_device(struct vfio_device *device) kref_put(&device->kref, vfio_device_release); } -void vfio_init_group_dev(struct vfio_device *device, struct device *dev, - const struct vfio_device_ops *ops); -void vfio_uninit_group_dev(struct vfio_device *device); int vfio_register_group_dev(struct vfio_device *device); int vfio_register_emulated_iommu_dev(struct vfio_device *device); void vfio_unregister_group_dev(struct vfio_device *device);