This is the basic infrastructure of a new miscdevice to hold the iommufd IOCTL API. It provides: - A miscdevice to create file descriptors to run the IOCTL interface over - A table based ioctl dispatch and centralized extendable pre-validation step - An xarray mapping userspace ID's to kernel objects. The design has multiple inter-related objects held within in a single IOMMUFD fd - A simple usage count to build a graph of object relations and protect against hostile userspace racing ioctls The only IOCTL provided in this patch is the generic 'destroy any object by handle' operation.
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| 1 | +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ | |
| 2 | +/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES. | |
| 3 | + */ | |
| 4 | +#ifndef _UAPI_IOMMUFD_H | |
| 5 | +#define _UAPI_IOMMUFD_H | |
| 6 | + | |
| 7 | +#include <linux/types.h> | |
| 8 | +#include <linux/ioctl.h> | |
| 9 | + | |
| 10 | +#define IOMMUFD_TYPE (';') | |
| 11 | + | |
| 12 | +/** | |
| 13 | + * DOC: General ioctl format | |
| 14 | + * | |
| 15 | + * The ioctl interface follows a general format to allow for extensibility. Each | |
| 16 | + * ioctl is passed in a structure pointer as the argument providing the size of | |
| 17 | + * the structure in the first u32. The kernel checks that any structure space | |
| 18 | + * beyond what it understands is 0. This allows userspace to use the backward | |
| 19 | + * compatible portion while consistently using the newer, larger, structures. | |
| 20 | + * | |
| 21 | + * ioctls use a standard meaning for common errnos: | |
| 22 | + * | |
| 23 | + * - ENOTTY: The IOCTL number itself is not supported at all | |
| 24 | + * - E2BIG: The IOCTL number is supported, but the provided structure has | |
| 25 | + * non-zero in a part the kernel does not understand. | |
| 26 | + * - EOPNOTSUPP: The IOCTL number is supported, and the structure is | |
| 27 | + * understood, however a known field has a value the kernel does not | |
| 28 | + * understand or support. | |
| 29 | + * - EINVAL: Everything about the IOCTL was understood, but a field is not | |
| 30 | + * correct. | |
| 31 | + * - ENOENT: An ID or IOVA provided does not exist. | |
| 32 | + * - ENOMEM: Out of memory. | |
| 33 | + * - EOVERFLOW: Mathematics overflowed. | |
| 34 | + * | |
| 35 | + * As well as additional errnos, within specific ioctls. | |
| 36 | + */ | |
| 37 | +enum { | |
| 38 | + IOMMUFD_CMD_BASE = 0x80, | |
| 39 | + IOMMUFD_CMD_DESTROY = IOMMUFD_CMD_BASE, | |
| 40 | +}; | |
| 41 | + | |
| 42 | +/** | |
| 43 | + * struct iommu_destroy - ioctl(IOMMU_DESTROY) | |
| 44 | + * @size: sizeof(struct iommu_destroy) | |
| 45 | + * @id: iommufd object ID to destroy. Can by any destroyable object type. | |
| 46 | + * | |
| 47 | + * Destroy any object held within iommufd. | |
| 48 | + */ | |
| 49 | +struct iommu_destroy { | |
| 50 | + __u32 size; | |
| 51 | + __u32 id; | |
| 52 | +}; | |
| 53 | +#define IOMMU_DESTROY _IO(IOMMUFD_TYPE, IOMMUFD_CMD_DESTROY) | |
| 54 | + | |
| 55 | +#endif | |