diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig index 850d86ca685b273344271eda7c95ad4f82b28244..da6e2ce77495b21ec127209664567b7e2f8f467e 100644 --- a/drivers/vfio/Kconfig +++ b/drivers/vfio/Kconfig @@ -31,6 +31,21 @@ menuconfig VFIO If you don't know what to do here, say N. +menuconfig VFIO_NOIOMMU + bool "VFIO No-IOMMU support" + depends on VFIO + help + VFIO is built on the ability to isolate devices using the IOMMU. + Only with an IOMMU can userspace access to DMA capable devices be + considered secure. VFIO No-IOMMU mode enables IOMMU groups for + devices without IOMMU backing for the purpose of re-using the VFIO + infrastructure in a non-secure mode. Use of this mode will result + in an unsupportable kernel and will therefore taint the kernel. + Device assignment to virtual machines is also not possible with + this mode since there is no IOMMU to provide DMA translation. + + If you don't know what to do here, say N. + source "drivers/vfio/pci/Kconfig" source "drivers/vfio/platform/Kconfig" source "virt/lib/Kconfig" diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 56bf6dbb93db7ac281a0af4fa01a8d212fd87670..2760a7ba3f309d1a344781c2f9a4eb6c3b3ff4aa 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -940,13 +940,13 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) if (pdev->hdr_type != PCI_HEADER_TYPE_NORMAL) return -EINVAL; - group = iommu_group_get(&pdev->dev); + group = vfio_iommu_group_get(&pdev->dev); if (!group) return -EINVAL; vdev = kzalloc(sizeof(*vdev), GFP_KERNEL); if (!vdev) { - iommu_group_put(group); + vfio_iommu_group_put(group, &pdev->dev); return -ENOMEM; } @@ -957,7 +957,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev); if (ret) { - iommu_group_put(group); + vfio_iommu_group_put(group, &pdev->dev); kfree(vdev); return ret; } @@ -993,7 +993,7 @@ static void vfio_pci_remove(struct pci_dev *pdev) if (!vdev) return; - iommu_group_put(pdev->dev.iommu_group); + vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev); kfree(vdev); if (vfio_pci_is_vga(pdev)) { diff --git a/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c b/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c index da5356f48d0b023225e62a672716e24d1ee94550..d4030d0c38e9c69b6498ed45624df5884ef8c003 100644 --- a/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c +++ b/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c @@ -110,7 +110,7 @@ int vfio_platform_amdxgbe_reset(struct vfio_platform_device *vdev) usleep_range(10, 15); count = 2000; - while (count-- && (ioread32(xgmac_regs->ioaddr + DMA_MR) & 1)) + while (--count && (ioread32(xgmac_regs->ioaddr + DMA_MR) & 1)) usleep_range(500, 600); if (!count) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 6070b793cbcb244d98a784bf6c41a5f0fabb662b..82f25cc1c460dee73c37b2b19895fb7d89bfb0d3 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -62,6 +62,7 @@ struct vfio_container { struct rw_semaphore group_lock; struct vfio_iommu_driver *iommu_driver; void *iommu_data; + bool noiommu; }; struct vfio_unbound_dev { @@ -84,6 +85,7 @@ struct vfio_group { struct list_head unbound_list; struct mutex unbound_lock; atomic_t opened; + bool noiommu; }; struct vfio_device { @@ -95,6 +97,128 @@ struct vfio_device { void *device_data; }; +#ifdef CONFIG_VFIO_NOIOMMU +static bool noiommu __read_mostly; +module_param_named(enable_unsafe_noiommu_mode, + noiommu, bool, S_IRUGO | S_IWUSR); +MODULE_PARM_DESC(enable_unsafe_noiommu_mode, "Enable UNSAFE, no-IOMMU mode. This mode provides no device isolation, no DMA translation, no host kernel protection, cannot be used for device assignment to virtual machines, requires RAWIO permissions, and will taint the kernel. If you do not know what this is for, step away. (default: false)"); +#endif + +/* + * vfio_iommu_group_{get,put} are only intended for VFIO bus driver probe + * and remove functions, any use cases other than acquiring the first + * reference for the purpose of calling vfio_add_group_dev() or removing + * that symmetric reference after vfio_del_group_dev() should use the raw + * iommu_group_{get,put} functions. In particular, vfio_iommu_group_put() + * removes the device from the dummy group and cannot be nested. + */ +struct iommu_group *vfio_iommu_group_get(struct device *dev) +{ + struct iommu_group *group; + int __maybe_unused ret; + + group = iommu_group_get(dev); + +#ifdef CONFIG_VFIO_NOIOMMU + /* + * With noiommu enabled, an IOMMU group will be created for a device + * that doesn't already have one and doesn't have an iommu_ops on their + * bus. We use iommu_present() again in the main code to detect these + * fake groups. + */ + if (group || !noiommu || iommu_present(dev->bus)) + return group; + + group = iommu_group_alloc(); + if (IS_ERR(group)) + return NULL; + + iommu_group_set_name(group, "vfio-noiommu"); + ret = iommu_group_add_device(group, dev); + iommu_group_put(group); + if (ret) + return NULL; + + /* + * Where to taint? At this point we've added an IOMMU group for a + * device that is not backed by iommu_ops, therefore any iommu_ + * callback using iommu_ops can legitimately Oops. So, while we may + * be about to give a DMA capable device to a user without IOMMU + * protection, which is clearly taint-worthy, let's go ahead and do + * it here. + */ + add_taint(TAINT_USER, LOCKDEP_STILL_OK); + dev_warn(dev, "Adding kernel taint for vfio-noiommu group on device\n"); +#endif + + return group; +} +EXPORT_SYMBOL_GPL(vfio_iommu_group_get); + +void vfio_iommu_group_put(struct iommu_group *group, struct device *dev) +{ +#ifdef CONFIG_VFIO_NOIOMMU + if (!iommu_present(dev->bus)) + iommu_group_remove_device(dev); +#endif + + iommu_group_put(group); +} +EXPORT_SYMBOL_GPL(vfio_iommu_group_put); + +#ifdef CONFIG_VFIO_NOIOMMU +static void *vfio_noiommu_open(unsigned long arg) +{ + if (arg != VFIO_NOIOMMU_IOMMU) + return ERR_PTR(-EINVAL); + if (!capable(CAP_SYS_RAWIO)) + return ERR_PTR(-EPERM); + + return NULL; +} + +static void vfio_noiommu_release(void *iommu_data) +{ +} + +static long vfio_noiommu_ioctl(void *iommu_data, + unsigned int cmd, unsigned long arg) +{ + if (cmd == VFIO_CHECK_EXTENSION) + return noiommu && (arg == VFIO_NOIOMMU_IOMMU) ? 1 : 0; + + return -ENOTTY; +} + +static int vfio_iommu_present(struct device *dev, void *unused) +{ + return iommu_present(dev->bus) ? 1 : 0; +} + +static int vfio_noiommu_attach_group(void *iommu_data, + struct iommu_group *iommu_group) +{ + return iommu_group_for_each_dev(iommu_group, NULL, + vfio_iommu_present) ? -EINVAL : 0; +} + +static void vfio_noiommu_detach_group(void *iommu_data, + struct iommu_group *iommu_group) +{ +} + +static const struct vfio_iommu_driver_ops vfio_noiommu_ops = { + .name = "vfio-noiommu", + .owner = THIS_MODULE, + .open = vfio_noiommu_open, + .release = vfio_noiommu_release, + .ioctl = vfio_noiommu_ioctl, + .attach_group = vfio_noiommu_attach_group, + .detach_group = vfio_noiommu_detach_group, +}; +#endif + + /** * IOMMU driver registration */ @@ -199,7 +323,8 @@ static void vfio_group_unlock_and_free(struct vfio_group *group) /** * Group objects - create, release, get, put, search */ -static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group) +static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group, + bool iommu_present) { struct vfio_group *group, *tmp; struct device *dev; @@ -217,6 +342,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group) atomic_set(&group->container_users, 0); atomic_set(&group->opened, 0); group->iommu_group = iommu_group; + group->noiommu = !iommu_present; group->nb.notifier_call = vfio_iommu_group_notifier; @@ -252,7 +378,8 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group) dev = device_create(vfio.class, NULL, MKDEV(MAJOR(vfio.group_devt), minor), - group, "%d", iommu_group_id(iommu_group)); + group, "%s%d", group->noiommu ? "noiommu-" : "", + iommu_group_id(iommu_group)); if (IS_ERR(dev)) { vfio_free_group_minor(minor); vfio_group_unlock_and_free(group); @@ -640,7 +767,7 @@ int vfio_add_group_dev(struct device *dev, group = vfio_group_get_from_iommu(iommu_group); if (!group) { - group = vfio_create_group(iommu_group); + group = vfio_create_group(iommu_group, iommu_present(dev->bus)); if (IS_ERR(group)) { iommu_group_put(iommu_group); return PTR_ERR(group); @@ -854,6 +981,14 @@ static long vfio_ioctl_check_extension(struct vfio_container *container, mutex_lock(&vfio.iommu_drivers_lock); list_for_each_entry(driver, &vfio.iommu_drivers_list, vfio_next) { + +#ifdef CONFIG_VFIO_NOIOMMU + if (!list_empty(&container->group_list) && + (container->noiommu != + (driver->ops == &vfio_noiommu_ops))) + continue; +#endif + if (!try_module_get(driver->ops->owner)) continue; @@ -925,6 +1060,15 @@ static long vfio_ioctl_set_iommu(struct vfio_container *container, list_for_each_entry(driver, &vfio.iommu_drivers_list, vfio_next) { void *data; +#ifdef CONFIG_VFIO_NOIOMMU + /* + * Only noiommu containers can use vfio-noiommu and noiommu + * containers can only use vfio-noiommu. + */ + if (container->noiommu != (driver->ops == &vfio_noiommu_ops)) + continue; +#endif + if (!try_module_get(driver->ops->owner)) continue; @@ -1187,6 +1331,9 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd) if (atomic_read(&group->container_users)) return -EINVAL; + if (group->noiommu && !capable(CAP_SYS_RAWIO)) + return -EPERM; + f = fdget(container_fd); if (!f.file) return -EBADF; @@ -1202,6 +1349,13 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd) down_write(&container->group_lock); + /* Real groups and fake groups cannot mix */ + if (!list_empty(&container->group_list) && + container->noiommu != group->noiommu) { + ret = -EPERM; + goto unlock_out; + } + driver = container->iommu_driver; if (driver) { ret = driver->ops->attach_group(container->iommu_data, @@ -1211,6 +1365,7 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd) } group->container = container; + container->noiommu = group->noiommu; list_add(&group->container_next, &container->group_list); /* Get a reference on the container and mark a user within the group */ @@ -1241,6 +1396,9 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf) !group->container->iommu_driver || !vfio_group_viable(group)) return -EINVAL; + if (group->noiommu && !capable(CAP_SYS_RAWIO)) + return -EPERM; + device = vfio_device_get_from_name(group, buf); if (!device) return -ENODEV; @@ -1283,6 +1441,10 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf) fd_install(ret, filep); + if (group->noiommu) + dev_warn(device->dev, "vfio-noiommu device opened by user " + "(%s:%d)\n", current->comm, task_pid_nr(current)); + return ret; } @@ -1371,6 +1533,11 @@ static int vfio_group_fops_open(struct inode *inode, struct file *filep) if (!group) return -ENODEV; + if (group->noiommu && !capable(CAP_SYS_RAWIO)) { + vfio_group_put(group); + return -EPERM; + } + /* Do we need multiple instances of the group open? Seems not. */ opened = atomic_cmpxchg(&group->opened, 0, 1); if (opened) { @@ -1533,6 +1700,11 @@ struct vfio_group *vfio_group_get_external_user(struct file *filep) if (!atomic_inc_not_zero(&group->container_users)) return ERR_PTR(-EINVAL); + if (group->noiommu) { + atomic_dec(&group->container_users); + return ERR_PTR(-EPERM); + } + if (!group->container->iommu_driver || !vfio_group_viable(group)) { atomic_dec(&group->container_users); @@ -1625,6 +1797,9 @@ static int __init vfio_init(void) request_module_nowait("vfio_iommu_type1"); request_module_nowait("vfio_iommu_spapr_tce"); +#ifdef CONFIG_VFIO_NOIOMMU + vfio_register_iommu_driver(&vfio_noiommu_ops); +#endif return 0; err_cdev_add: @@ -1641,6 +1816,9 @@ static void __exit vfio_cleanup(void) { WARN_ON(!list_empty(&vfio.group_list)); +#ifdef CONFIG_VFIO_NOIOMMU + vfio_unregister_iommu_driver(&vfio_noiommu_ops); +#endif idr_destroy(&vfio.group_idr); cdev_del(&vfio.group_cdev); unregister_chrdev_region(vfio.group_devt, MINORMASK); diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 59d47cb638d5d18aac6700157ecc9be918772f91..6f1ea3dddbad9a75dd094d8613fb426742f844e4 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -995,7 +995,7 @@ static long vfio_iommu_type1_ioctl(void *iommu_data, if (info.argsz < minsz) return -EINVAL; - info.flags = 0; + info.flags = VFIO_IOMMU_INFO_PGSIZES; info.iova_pgsizes = vfio_pgsize_bitmap(iommu); diff --git a/include/linux/vfio.h b/include/linux/vfio.h index ddb44097538245f17e882efff635143ada49e089..610a86a892b8896363ece505cdbe686096505cfc 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -44,6 +44,9 @@ struct vfio_device_ops { void (*request)(void *device_data, unsigned int count); }; +extern struct iommu_group *vfio_iommu_group_get(struct device *dev); +extern void vfio_iommu_group_put(struct iommu_group *group, struct device *dev); + extern int vfio_add_group_dev(struct device *dev, const struct vfio_device_ops *ops, void *device_data); diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 9fd7b5d8df2fa357f434a899cccfa7810f826107..7d7a4c6f2090648a399ab242c361f3f256798035 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -38,6 +38,13 @@ #define VFIO_SPAPR_TCE_v2_IOMMU 7 +/* + * The No-IOMMU IOMMU offers no translation or isolation for devices and + * supports no ioctls outside of VFIO_CHECK_EXTENSION. Use of VFIO's No-IOMMU + * code will taint the host kernel and should be used with extreme caution. + */ +#define VFIO_NOIOMMU_IOMMU 8 + /* * The IOCTL interface is designed for extensibility by embedding the * structure length (argsz) and flags into structures passed between @@ -568,8 +575,10 @@ struct vfio_iommu_spapr_tce_create { __u32 flags; /* in */ __u32 page_shift; + __u32 __resv1; __u64 window_size; __u32 levels; + __u32 __resv2; /* out */ __u64 start_addr; };