From patchwork Thu Sep 1 14:37:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Tian, Kevin" X-Patchwork-Id: 12961914 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 16256ECAAD8 for ; Thu, 1 Sep 2022 07:17:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233707AbiIAHRt (ORCPT ); Thu, 1 Sep 2022 03:17:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233629AbiIAHRp (ORCPT ); Thu, 1 Sep 2022 03:17:45 -0400 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0177125E8A; Thu, 1 Sep 2022 00:17:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1662016662; x=1693552662; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=e83uQmoLWDUcDyfr3MZBIiqrTNzpPSs5GIlAGpeBrhE=; b=k8dkzCAzKD7IP3avJNXrYx3tvBS6ps4ZONwUQ6m4i9B2dkKIsKsopyiA mltv6Ce2a4rk0aDRaIlmh19K80PnQPhhQbeyOhZTJPwb0giMlQBSsKRnA LjS7JYnH3CLJN4pOUtXpzBAKrZaCivQc7pX5niqcQAUOpxJOIZdiQEJAI eT1Ek8rpFhoBOjQ1981UpG1vh6qNXW0/xxIrhkaTkojuWDTRn8ZpuSy4z IJFd8k0JCYe+FD9nQaCqzcvgW99yahxYasn6x6nDkw7dPReDVoli6CSsa fS1eR/kInTjDcZCa1sQjby/8Z02RkqsNMsXWWqjt38GManoF4so7VEBrA w==; X-IronPort-AV: E=McAfee;i="6500,9779,10456"; a="276039173" X-IronPort-AV: E=Sophos;i="5.93,280,1654585200"; d="scan'208";a="276039173" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Sep 2022 00:17:42 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,280,1654585200"; d="scan'208";a="673719836" Received: from sqa-gate.sh.intel.com (HELO michael.clx.dev.tsp.org) ([10.239.48.212]) by fmsmga008.fm.intel.com with ESMTP; 01 Sep 2022 00:17:34 -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 v2 01/15] vfio: Add helpers for unifying vfio_device life cycle Date: Thu, 1 Sep 2022 22:37:33 +0800 Message-Id: <20220901143747.32858-2-kevin.tian@intel.com> X-Mailer: git-send-email 2.21.3 In-Reply-To: <20220901143747.32858-1-kevin.tian@intel.com> References: <20220901143747.32858-1-kevin.tian@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The idea is to let vfio core manage the vfio_device life cycle instead of duplicating the logic cross drivers. This is also a preparatory step for adding struct device into vfio_device. New pair of helpers together with a kref in vfio_device: - vfio_alloc_device() - vfio_put_device() Drivers can register @init/@release callbacks to manage any priviate state wrapping the vfio_device. However vfio-ccw doesn't fit this model due to a life cycle mess that its private structure mixes both parent and mdev info hence must be allocated/freed outside of the life cycle of vfio device. Per prior discussions this won't be fixed in short term by IBM folks. Instead of waiting introduce another helper vfio_init_device() so ccw can call it to initialize a pre-allocated vfio_device. Further implication of the ccw trick is that vfio_device cannot be freed uniformly in vfio core. Instead, require *EVERY* driver to implement @release and free vfio_device inside. Then ccw can choose to delay the free at its own discretion. Another trick down the road is that kvzalloc() is used to accommodate the need of gvt which uses vzalloc() while all others use kzalloc(). So drivers should call a helper vfio_free_device() to free the vfio_device instead of assuming that kfree() or vfree() is appliable. Later once the ccw mess is fixed we can remove those tricks and fully handle structure alloc/free in vfio core. Existing vfio_{un}init_group_dev() will be deprecated after all existing usages are converted to the new model. Suggested-by: Jason Gunthorpe Co-developed-by: Yi Liu Signed-off-by: Yi Liu Signed-off-by: Kevin Tian Reviewed-by: Tony Krowiak Reviewed-by: Jason Gunthorpe Reviewed-by: Eric Auger --- drivers/vfio/vfio_main.c | 92 ++++++++++++++++++++++++++++++++++++++++ include/linux/vfio.h | 25 ++++++++++- 2 files changed, 116 insertions(+), 1 deletion(-) diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index 7cb56c382c97..c9d982131265 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -496,6 +496,98 @@ void vfio_uninit_group_dev(struct vfio_device *device) } EXPORT_SYMBOL_GPL(vfio_uninit_group_dev); +/* Release helper called by vfio_put_device() */ +void vfio_device_release(struct kref *kref) +{ + struct vfio_device *device = + container_of(kref, struct vfio_device, kref); + + vfio_uninit_group_dev(device); + + /* + * kvfree() cannot be done here due to a life cycle mess in + * vfio-ccw. Before the ccw part is fixed all drivers are + * required to support @release and call vfio_free_device() + * from there. + */ + device->ops->release(device); +} +EXPORT_SYMBOL_GPL(vfio_device_release); + +/* + * Alloc and initialize vfio_device so it can be registered to vfio + * core. + * + * Drivers should use the wrapper vfio_alloc_device() for allocation. + * @size is the size of the structure to be allocated, including any + * private data used by the driver. + * + * Driver may provide an @init callback to cover device private data. + * + * Use vfio_put_device() to release the structure after success return. + */ +struct vfio_device *_vfio_alloc_device(size_t size, struct device *dev, + const struct vfio_device_ops *ops) +{ + struct vfio_device *device; + int ret; + + if (WARN_ON(size < sizeof(struct vfio_device))) + return ERR_PTR(-EINVAL); + + device = kvzalloc(size, GFP_KERNEL); + if (!device) + return ERR_PTR(-ENOMEM); + + ret = vfio_init_device(device, dev, ops); + if (ret) + goto out_free; + return device; + +out_free: + kvfree(device); + return ERR_PTR(ret); +} +EXPORT_SYMBOL_GPL(_vfio_alloc_device); + +/* + * Initialize a vfio_device so it can be registered to vfio core. + * + * Only vfio-ccw driver should call this interface. + */ +int vfio_init_device(struct vfio_device *device, struct device *dev, + const struct vfio_device_ops *ops) +{ + int ret; + + vfio_init_group_dev(device, dev, ops); + + if (ops->init) { + ret = ops->init(device); + if (ret) + goto out_uninit; + } + + kref_init(&device->kref); + return 0; + +out_uninit: + vfio_uninit_group_dev(device); + return ret; +} +EXPORT_SYMBOL_GPL(vfio_init_device); + +/* + * The helper called by driver @release callback to free the device + * structure. Drivers which don't have private data to clean can + * simply use this helper as its @release. + */ +void vfio_free_device(struct vfio_device *device) +{ + kvfree(device); +} +EXPORT_SYMBOL_GPL(vfio_free_device); + static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev, enum vfio_group_type type) { diff --git a/include/linux/vfio.h b/include/linux/vfio.h index e05ddc6fe6a5..e1e9e8352903 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -45,7 +45,8 @@ struct vfio_device { struct kvm *kvm; /* Members below here are private, not for driver use */ - refcount_t refcount; + struct kref kref; /* object life cycle */ + refcount_t refcount; /* user count on registered device*/ unsigned int open_count; struct completion comp; struct list_head group_next; @@ -55,6 +56,8 @@ struct vfio_device { /** * struct vfio_device_ops - VFIO bus driver device callbacks * + * @init: initialize private fields in device structure + * @release: Reclaim private fields in device structure * @open_device: Called when the first file descriptor is opened for this device * @close_device: Opposite of open_device * @read: Perform read(2) on device file descriptor @@ -72,6 +75,8 @@ struct vfio_device { */ struct vfio_device_ops { char *name; + int (*init)(struct vfio_device *vdev); + void (*release)(struct vfio_device *vdev); int (*open_device)(struct vfio_device *vdev); void (*close_device)(struct vfio_device *vdev); ssize_t (*read)(struct vfio_device *vdev, char __user *buf, @@ -137,6 +142,24 @@ static inline int vfio_check_feature(u32 flags, size_t argsz, u32 supported_ops, return 1; } +struct vfio_device *_vfio_alloc_device(size_t size, struct device *dev, + const struct vfio_device_ops *ops); +#define vfio_alloc_device(dev_struct, member, dev, ops) \ + container_of(_vfio_alloc_device(sizeof(struct dev_struct) + \ + BUILD_BUG_ON_ZERO(offsetof( \ + struct dev_struct, member)), \ + dev, ops), \ + struct dev_struct, member) + +int vfio_init_device(struct vfio_device *device, struct device *dev, + const struct vfio_device_ops *ops); +void vfio_free_device(struct vfio_device *device); +void vfio_device_release(struct kref *kref); +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);