From patchwork Sat Aug 27 17:10:23 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Tian, Kevin" X-Patchwork-Id: 12956908 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 06FF4C0502E for ; Sat, 27 Aug 2022 09:50:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234221AbiH0JuA (ORCPT ); Sat, 27 Aug 2022 05:50:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231391AbiH0Jt6 (ORCPT ); Sat, 27 Aug 2022 05:49:58 -0400 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 831783F1C4; Sat, 27 Aug 2022 02:49:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661593796; x=1693129796; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Dx5otHghkdbbjEb4+eyGPz5L7FH1uZUkRIY1rfmKp+s=; b=FvB/GMng7D+uUw7Fvf7PcsnL+agTiZP4VT9FuLLtIWn6dnjR1SKZcPa7 FC2percl9JKstfVja9ErSjxCZW1vQo0XODdA6tTDhlxV8xIKC1e0QkA0R L1BI+K6W4n9ncFPZBBVrHfwF0QrRwL2ct0+XfpMectZIJT0RTxG+mXZH7 6WI0tAcF8ufyv8NGQ08HjDTQxvTwF+vOlRMeCmt7p52sSifEQbHdsDyar OXDLquzQyCPt8MUfSgVNuKR+L6qkPc1MAtkd3fNICN9SXPmY9BlNxFdTi QMNfiKbnoo7jahs6Gqhau4F4gSmaZkXhpdVpoWUF4IOGHo3HEUym0/CQa A==; X-IronPort-AV: E=McAfee;i="6500,9779,10451"; a="277666348" X-IronPort-AV: E=Sophos;i="5.93,267,1654585200"; d="scan'208";a="277666348" 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 02:49:55 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,267,1654585200"; d="scan'208";a="640353768" 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 02:49:46 -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 01/15] vfio: Add helpers for unifying vfio_device life cycle Date: Sun, 28 Aug 2022 01:10:23 +0800 Message-Id: <20220827171037.30297-2-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 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 private 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/free'ed 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 free'ed 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 --- 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..af8aad116f2b 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); +/* + * 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); + +/* 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); + 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);