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Fri, 6 May 2022 00:08:52 +0000 Received: from MN2PR12MB4192.namprd12.prod.outlook.com ([fe80::ec2d:9167:1b47:2db2]) by MN2PR12MB4192.namprd12.prod.outlook.com ([fe80::ec2d:9167:1b47:2db2%6]) with mapi id 15.20.5206.027; Fri, 6 May 2022 00:08:52 +0000 From: Jason Gunthorpe To: Alexander Gordeev , David Airlie , Alex Williamson , Christian Borntraeger , Cornelia Huck , Jonathan Corbet , Daniel Vetter , dri-devel@lists.freedesktop.org, Harald Freudenberger , Vasily Gorbik , Heiko Carstens , intel-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, Jani Nikula , Jason Herne , Joonas Lahtinen , kvm@vger.kernel.org, Kirti Wankhede , linux-doc@vger.kernel.org, linux-s390@vger.kernel.org, Matthew Rosato , Peter Oberparleiter , Halil Pasic , Rodrigo Vivi , Sven Schnelle , Tvrtko Ursulin , Vineeth Vijayan , Zhenyu Wang , Zhi Wang Subject: [PATCH v4 7/7] vfio: Remove calls to vfio_group_add_container_user() Date: Thu, 5 May 2022 21:08:45 -0300 Message-Id: <7-v4-8045e76bf00b+13d-vfio_mdev_no_group_jgg@nvidia.com> In-Reply-To: <0-v4-8045e76bf00b+13d-vfio_mdev_no_group_jgg@nvidia.com> References: X-ClientProxiedBy: MN2PR02CA0014.namprd02.prod.outlook.com (2603:10b6:208:fc::27) To MN2PR12MB4192.namprd12.prod.outlook.com (2603:10b6:208:1d5::15) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: e75e0ca0-a46e-419d-033c-08da2ef497f2 X-MS-TrafficTypeDiagnostic: BYAPR12MB2934:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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Thus, so long as drivers call functions within their open_device()/close_device() region they do not need to worry about the container_users. These functions can all only be called between open_device() and close_device(): vfio_pin_pages() vfio_unpin_pages() vfio_dma_rw() vfio_register_notifier() vfio_unregister_notifier() Eliminate the calls to vfio_group_add_container_user() and add vfio_assert_device_open() to detect driver mis-use. This causes the close_device() op to check device->open_count so always leave it elevated while calling the op. Reviewed-by: Christoph Hellwig Reviewed-by: Kevin Tian Signed-off-by: Jason Gunthorpe --- drivers/vfio/vfio.c | 80 ++++++++++----------------------------------- 1 file changed, 17 insertions(+), 63 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index c651c4805acd59..8bb38941c1dfd8 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -1115,6 +1115,12 @@ static int vfio_group_add_container_user(struct vfio_group *group) static const struct file_operations vfio_device_fops; +/* true if the vfio_device has open_device() called but not close_device() */ +static bool vfio_assert_device_open(struct vfio_device *device) +{ + return !WARN_ON_ONCE(!READ_ONCE(device->open_count)); +} + static int vfio_group_get_device_fd(struct vfio_group *group, char *buf) { struct vfio_device *device; @@ -1329,8 +1335,10 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep) struct vfio_device *device = filep->private_data; mutex_lock(&device->dev_set->lock); - if (!--device->open_count && device->ops->close_device) + vfio_assert_device_open(device); + if (device->open_count == 1 && device->ops->close_device) device->ops->close_device(device); + device->open_count--; mutex_unlock(&device->dev_set->lock); module_put(device->dev->driver->owner); @@ -1897,7 +1905,8 @@ int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn, struct vfio_iommu_driver *driver; int ret; - if (!user_pfn || !phys_pfn || !npage) + if (!user_pfn || !phys_pfn || !npage || + !vfio_assert_device_open(device)) return -EINVAL; if (npage > VFIO_PIN_PAGES_MAX_ENTRIES) @@ -1906,10 +1915,6 @@ int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn, if (group->dev_counter > 1) return -EINVAL; - ret = vfio_group_add_container_user(group); - if (ret) - return ret; - container = group->container; driver = container->iommu_driver; if (likely(driver && driver->ops->pin_pages)) @@ -1919,8 +1924,6 @@ int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn, else ret = -ENOTTY; - vfio_group_try_dissolve_container(group); - return ret; } EXPORT_SYMBOL(vfio_pin_pages); @@ -1941,16 +1944,12 @@ int vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn, struct vfio_iommu_driver *driver; int ret; - if (!user_pfn || !npage) + if (!user_pfn || !npage || !vfio_assert_device_open(device)) return -EINVAL; if (npage > VFIO_PIN_PAGES_MAX_ENTRIES) return -E2BIG; - ret = vfio_group_add_container_user(device->group); - if (ret) - return ret; - container = device->group->container; driver = container->iommu_driver; if (likely(driver && driver->ops->unpin_pages)) @@ -1959,8 +1958,6 @@ int vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn, else ret = -ENOTTY; - vfio_group_try_dissolve_container(device->group); - return ret; } EXPORT_SYMBOL(vfio_unpin_pages); @@ -1989,13 +1986,9 @@ int vfio_dma_rw(struct vfio_device *device, dma_addr_t user_iova, void *data, struct vfio_iommu_driver *driver; int ret = 0; - if (!data || len <= 0) + if (!data || len <= 0 || !vfio_assert_device_open(device)) return -EINVAL; - ret = vfio_group_add_container_user(device->group); - if (ret) - return ret; - container = device->group->container; driver = container->iommu_driver; @@ -2004,9 +1997,6 @@ int vfio_dma_rw(struct vfio_device *device, dma_addr_t user_iova, void *data, user_iova, data, len, write); else ret = -ENOTTY; - - vfio_group_try_dissolve_container(device->group); - return ret; } EXPORT_SYMBOL(vfio_dma_rw); @@ -2019,10 +2009,6 @@ static int vfio_register_iommu_notifier(struct vfio_group *group, struct vfio_iommu_driver *driver; int ret; - ret = vfio_group_add_container_user(group); - if (ret) - return -EINVAL; - container = group->container; driver = container->iommu_driver; if (likely(driver && driver->ops->register_notifier)) @@ -2030,9 +2016,6 @@ static int vfio_register_iommu_notifier(struct vfio_group *group, events, nb); else ret = -ENOTTY; - - vfio_group_try_dissolve_container(group); - return ret; } @@ -2043,10 +2026,6 @@ static int vfio_unregister_iommu_notifier(struct vfio_group *group, struct vfio_iommu_driver *driver; int ret; - ret = vfio_group_add_container_user(group); - if (ret) - return -EINVAL; - container = group->container; driver = container->iommu_driver; if (likely(driver && driver->ops->unregister_notifier)) @@ -2054,9 +2033,6 @@ static int vfio_unregister_iommu_notifier(struct vfio_group *group, nb); else ret = -ENOTTY; - - vfio_group_try_dissolve_container(group); - return ret; } @@ -2085,10 +2061,6 @@ static int vfio_register_group_notifier(struct vfio_group *group, if (*events) return -EINVAL; - ret = vfio_group_add_container_user(group); - if (ret) - return -EINVAL; - ret = blocking_notifier_chain_register(&group->notifier, nb); /* @@ -2098,25 +2070,6 @@ static int vfio_register_group_notifier(struct vfio_group *group, if (!ret && set_kvm && group->kvm) blocking_notifier_call_chain(&group->notifier, VFIO_GROUP_NOTIFY_SET_KVM, group->kvm); - - vfio_group_try_dissolve_container(group); - - return ret; -} - -static int vfio_unregister_group_notifier(struct vfio_group *group, - struct notifier_block *nb) -{ - int ret; - - ret = vfio_group_add_container_user(group); - if (ret) - return -EINVAL; - - ret = blocking_notifier_chain_unregister(&group->notifier, nb); - - vfio_group_try_dissolve_container(group); - return ret; } @@ -2127,7 +2080,8 @@ int vfio_register_notifier(struct vfio_device *device, struct vfio_group *group = device->group; int ret; - if (!nb || !events || (*events == 0)) + if (!nb || !events || (*events == 0) || + !vfio_assert_device_open(device)) return -EINVAL; switch (type) { @@ -2151,7 +2105,7 @@ int vfio_unregister_notifier(struct vfio_device *device, struct vfio_group *group = device->group; int ret; - if (!nb) + if (!nb || !vfio_assert_device_open(device)) return -EINVAL; switch (type) { @@ -2159,7 +2113,7 @@ int vfio_unregister_notifier(struct vfio_device *device, ret = vfio_unregister_iommu_notifier(group, nb); break; case VFIO_GROUP_NOTIFY: - ret = vfio_unregister_group_notifier(group, nb); + ret = blocking_notifier_chain_unregister(&group->notifier, nb); break; default: ret = -EINVAL;