From a15ac665b9e9c90b1557499f2a46c1e89d29154a Mon Sep 17 00:00:00 2001 From: Eric Farman Date: Thu, 3 Dec 2020 22:35:11 +0100 Subject: vfio-mdev: Wire in a request handler for mdev parent While performing some destructive tests with vfio-ccw, where the paths to a device are forcible removed and thus the device itself is unreachable, it is rather easy to end up in an endless loop in vfio_del_group_dev() due to the lack of a request callback for the associated device. In this example, one MDEV (77c) is used by a guest, while another (77b) is not. The symptom is that the iommu is detached from the mdev for 77b, but not 77c, until that guest is shutdown: [ 238.794867] vfio_ccw 0.0.077b: MDEV: Unregistering [ 238.794996] vfio_mdev 11f2d2bc-4083-431d-a023-eff72715c4f0: Removing from iommu group 2 [ 238.795001] vfio_mdev 11f2d2bc-4083-431d-a023-eff72715c4f0: MDEV: detaching iommu [ 238.795036] vfio_ccw 0.0.077c: MDEV: Unregistering ...silence... Let's wire in the request call back to the mdev device, so that a device being physically removed from the host can be (gracefully?) handled by the parent device at the time the device is removed. Add a message when registering the device if a driver doesn't provide this callback, so a clue is given that this same loop may be encountered in a similar situation, and a message when this occurs instead of the awkward silence noted above. Signed-off-by: Eric Farman Reviewed-by: Cornelia Huck Signed-off-by: Alex Williamson --- include/linux/mdev.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux') diff --git a/include/linux/mdev.h b/include/linux/mdev.h index 0ce30ca78db0..9004375c462e 100644 --- a/include/linux/mdev.h +++ b/include/linux/mdev.h @@ -72,6 +72,9 @@ struct device *mdev_get_iommu_device(struct device *dev); * @mmap: mmap callback * @mdev: mediated device structure * @vma: vma structure + * @request: request callback to release device + * @mdev: mediated device structure + * @count: request sequence number * Parent device that support mediated device should be registered with mdev * module with mdev_parent_ops structure. **/ @@ -92,6 +95,7 @@ struct mdev_parent_ops { long (*ioctl)(struct mdev_device *mdev, unsigned int cmd, unsigned long arg); int (*mmap)(struct mdev_device *mdev, struct vm_area_struct *vma); + void (*request)(struct mdev_device *mdev, unsigned int count); }; /* interface for exporting mdev supported type attributes */ -- cgit v1.3-18-gd494 From bdfae1c9a913930eae5ea506733aa7c285e12a06 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Wed, 9 Dec 2020 09:44:44 +0800 Subject: vfio/type1: Add vfio_group_iommu_domain() Add the API for getting the domain from a vfio group. This could be used by the physical device drivers which rely on the vfio/mdev framework for mediated device user level access. The typical use case like below: unsigned int pasid; struct vfio_group *vfio_group; struct iommu_domain *iommu_domain; struct device *dev = mdev_dev(mdev); struct device *iommu_device = mdev_get_iommu_device(dev); if (!iommu_device || !iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX)) return -EINVAL; vfio_group = vfio_group_get_external_user_from_dev(dev); if (IS_ERR_OR_NULL(vfio_group)) return -EFAULT; iommu_domain = vfio_group_iommu_domain(vfio_group); if (IS_ERR_OR_NULL(iommu_domain)) { vfio_group_put_external_user(vfio_group); return -EFAULT; } pasid = iommu_aux_get_pasid(iommu_domain, iommu_device); if (pasid < 0) { vfio_group_put_external_user(vfio_group); return -EFAULT; } /* Program device context with pasid value. */ ... Signed-off-by: Lu Baolu Signed-off-by: Alex Williamson --- drivers/vfio/vfio.c | 18 ++++++++++++++++++ drivers/vfio/vfio_iommu_type1.c | 24 ++++++++++++++++++++++++ include/linux/vfio.h | 4 ++++ 3 files changed, 46 insertions(+) (limited to 'include/linux') diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 2151bc7f87ab..4ad8a35667a7 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -2331,6 +2331,24 @@ int vfio_unregister_notifier(struct device *dev, enum vfio_notify_type type, } EXPORT_SYMBOL(vfio_unregister_notifier); +struct iommu_domain *vfio_group_iommu_domain(struct vfio_group *group) +{ + struct vfio_container *container; + struct vfio_iommu_driver *driver; + + if (!group) + return ERR_PTR(-EINVAL); + + container = group->container; + driver = container->iommu_driver; + if (likely(driver && driver->ops->group_iommu_domain)) + return driver->ops->group_iommu_domain(container->iommu_data, + group->iommu_group); + + return ERR_PTR(-ENOTTY); +} +EXPORT_SYMBOL_GPL(vfio_group_iommu_domain); + /** * Module/class support */ diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 67e827638995..0b4dedaa9128 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -2980,6 +2980,29 @@ static int vfio_iommu_type1_dma_rw(void *iommu_data, dma_addr_t user_iova, return ret; } +static struct iommu_domain * +vfio_iommu_type1_group_iommu_domain(void *iommu_data, + struct iommu_group *iommu_group) +{ + struct iommu_domain *domain = ERR_PTR(-ENODEV); + struct vfio_iommu *iommu = iommu_data; + struct vfio_domain *d; + + if (!iommu || !iommu_group) + return ERR_PTR(-EINVAL); + + mutex_lock(&iommu->lock); + list_for_each_entry(d, &iommu->domain_list, next) { + if (find_iommu_group(d, iommu_group)) { + domain = d->domain; + break; + } + } + mutex_unlock(&iommu->lock); + + return domain; +} + static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = { .name = "vfio-iommu-type1", .owner = THIS_MODULE, @@ -2993,6 +3016,7 @@ static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = { .register_notifier = vfio_iommu_type1_register_notifier, .unregister_notifier = vfio_iommu_type1_unregister_notifier, .dma_rw = vfio_iommu_type1_dma_rw, + .group_iommu_domain = vfio_iommu_type1_group_iommu_domain, }; static int __init vfio_iommu_type1_init(void) diff --git a/include/linux/vfio.h b/include/linux/vfio.h index 38d3c6a8dc7e..f45940b38a02 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -90,6 +90,8 @@ struct vfio_iommu_driver_ops { struct notifier_block *nb); int (*dma_rw)(void *iommu_data, dma_addr_t user_iova, void *data, size_t count, bool write); + struct iommu_domain *(*group_iommu_domain)(void *iommu_data, + struct iommu_group *group); }; extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops); @@ -126,6 +128,8 @@ extern int vfio_group_unpin_pages(struct vfio_group *group, extern int vfio_dma_rw(struct vfio_group *group, dma_addr_t user_iova, void *data, size_t len, bool write); +extern struct iommu_domain *vfio_group_iommu_domain(struct vfio_group *group); + /* each type has independent events */ enum vfio_notify_type { VFIO_IOMMU_NOTIFY = 0, -- cgit v1.3-18-gd494