Hi Jason, On 11/16/22 22:00, Jason Gunthorpe wrote: > 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. > > Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> > Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx> > Tested-by: Nicolin Chen <nicolinc@xxxxxxxxxx> > Tested-by: Yi Liu <yi.l.liu@xxxxxxxxx> > Tested-by: Lixiao Yang <lixiao.yang@xxxxxxxxx> > Tested-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx> > Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx> > Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx> > --- > .../userspace-api/ioctl/ioctl-number.rst | 1 + > MAINTAINERS | 12 + > drivers/iommu/Kconfig | 1 + > drivers/iommu/Makefile | 2 +- > drivers/iommu/iommufd/Kconfig | 12 + > drivers/iommu/iommufd/Makefile | 5 + > drivers/iommu/iommufd/iommufd_private.h | 109 ++++++ > drivers/iommu/iommufd/main.c | 342 ++++++++++++++++++ > include/linux/iommufd.h | 31 ++ > include/uapi/linux/iommufd.h | 55 +++ > 10 files changed, 569 insertions(+), 1 deletion(-) > create mode 100644 drivers/iommu/iommufd/Kconfig > create mode 100644 drivers/iommu/iommufd/Makefile > create mode 100644 drivers/iommu/iommufd/iommufd_private.h > create mode 100644 drivers/iommu/iommufd/main.c > create mode 100644 include/linux/iommufd.h > create mode 100644 include/uapi/linux/iommufd.h > > diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst > index 5f81e2a24a5c04..eb045fc495a4e3 100644 > --- a/Documentation/userspace-api/ioctl/ioctl-number.rst > +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst > @@ -105,6 +105,7 @@ Code Seq# Include File Comments > '8' all SNP8023 advanced NIC card > <mailto:mcr@xxxxxxxxxxx> > ';' 64-7F linux/vfio.h > +';' 80-FF linux/iommufd.h > '=' 00-3f uapi/linux/ptp_clock.h <mailto:richardcochran@xxxxxxxxx> > '@' 00-0F linux/radeonfb.h conflict! > '@' 00-0F drivers/video/aty/aty128fb.c conflict! > diff --git a/MAINTAINERS b/MAINTAINERS > index 379945f82a6438..c0a93779731d7e 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -10717,6 +10717,18 @@ F: drivers/iommu/dma-iommu.h > F: drivers/iommu/iova.c > F: include/linux/iova.h > > +IOMMUFD > +M: Jason Gunthorpe <jgg@xxxxxxxxxx> > +M: Kevin Tian <kevin.tian@xxxxxxxxx> > +L: iommu@xxxxxxxxxxxxxxx > +S: Maintained > +T: git git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd.git > +F: Documentation/userspace-api/iommufd.rst > +F: drivers/iommu/iommufd/ > +F: include/linux/iommufd.h > +F: include/uapi/linux/iommufd.h > +F: tools/testing/selftests/iommu/ > + > IOMMU SUBSYSTEM > M: Joerg Roedel <joro@xxxxxxxxxx> > M: Will Deacon <will@xxxxxxxxxx> > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig > index dc5f7a156ff5ec..319966cde5cf6c 100644 > --- a/drivers/iommu/Kconfig > +++ b/drivers/iommu/Kconfig > @@ -188,6 +188,7 @@ config MSM_IOMMU > > source "drivers/iommu/amd/Kconfig" > source "drivers/iommu/intel/Kconfig" > +source "drivers/iommu/iommufd/Kconfig" > > config IRQ_REMAP > bool "Support for Interrupt Remapping" > diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile > index 7fbf6a3376620e..f461d065138564 100644 > --- a/drivers/iommu/Makefile > +++ b/drivers/iommu/Makefile > @@ -1,5 +1,5 @@ > # SPDX-License-Identifier: GPL-2.0 > -obj-y += amd/ intel/ arm/ > +obj-y += amd/ intel/ arm/ iommufd/ > obj-$(CONFIG_IOMMU_API) += iommu.o > obj-$(CONFIG_IOMMU_API) += iommu-traces.o > obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o > diff --git a/drivers/iommu/iommufd/Kconfig b/drivers/iommu/iommufd/Kconfig > new file mode 100644 > index 00000000000000..6d65d0f06f169f > --- /dev/null > +++ b/drivers/iommu/iommufd/Kconfig > @@ -0,0 +1,12 @@ > +# SPDX-License-Identifier: GPL-2.0-only > +config IOMMUFD > + tristate "IOMMU Userspace API" > + select INTERVAL_TREE > + select INTERVAL_TREE_SPAN_ITER > + select IOMMU_API > + default n > + help > + Provides /dev/iommu the user API to control the IOMMU subsystem as > + it relates to managing IO page tables that point at user space memory. nit: missing ',' after /dev/iommu or Provides /dev/iommu user API > + > + If you don't know what to do here, say N. > diff --git a/drivers/iommu/iommufd/Makefile b/drivers/iommu/iommufd/Makefile > new file mode 100644 > index 00000000000000..a07a8cffe937c6 > --- /dev/null > +++ b/drivers/iommu/iommufd/Makefile > @@ -0,0 +1,5 @@ > +# SPDX-License-Identifier: GPL-2.0-only > +iommufd-y := \ > + main.o > + > +obj-$(CONFIG_IOMMUFD) += iommufd.o > diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h > new file mode 100644 > index 00000000000000..d523e7967b1440 > --- /dev/null > +++ b/drivers/iommu/iommufd/iommufd_private.h > @@ -0,0 +1,109 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES > + */ > +#ifndef __IOMMUFD_PRIVATE_H > +#define __IOMMUFD_PRIVATE_H > + > +#include <linux/rwsem.h> > +#include <linux/xarray.h> > +#include <linux/refcount.h> > +#include <linux/uaccess.h> > + > +struct iommufd_ctx { > + struct file *file; > + struct xarray objects; > +}; > + > +struct iommufd_ucmd { > + struct iommufd_ctx *ictx; > + void __user *ubuffer; > + u32 user_size; > + void *cmd; > +}; > + > +/* Copy the response in ucmd->cmd back to userspace. */ > +static inline int iommufd_ucmd_respond(struct iommufd_ucmd *ucmd, > + size_t cmd_len) > +{ > + if (copy_to_user(ucmd->ubuffer, ucmd->cmd, > + min_t(size_t, ucmd->user_size, cmd_len))) > + return -EFAULT; > + return 0; > +} > + > +enum iommufd_object_type { > + IOMMUFD_OBJ_NONE, > + IOMMUFD_OBJ_ANY = IOMMUFD_OBJ_NONE, > +}; > + > +/* Base struct for all objects with a userspace ID handle. */ > +struct iommufd_object { > + struct rw_semaphore destroy_rwsem; > + refcount_t users; > + enum iommufd_object_type type; > + unsigned int id; > +}; > + > +static inline bool iommufd_lock_obj(struct iommufd_object *obj) > +{ > + if (!down_read_trylock(&obj->destroy_rwsem)) > + return false; > + if (!refcount_inc_not_zero(&obj->users)) { > + up_read(&obj->destroy_rwsem); > + return false; > + } > + return true; > +} > + > +struct iommufd_object *iommufd_get_object(struct iommufd_ctx *ictx, u32 id, > + enum iommufd_object_type type); > +static inline void iommufd_put_object(struct iommufd_object *obj) > +{ > + refcount_dec(&obj->users); > + up_read(&obj->destroy_rwsem); > +} > + > +/** > + * iommufd_ref_to_users() - Switch from destroy_rwsem to users refcount > + * protection > + * @obj - Object to release > + * > + * Objects have two refcount protections (destroy_rwsem and the refcount_t > + * users). Holding either of these will prevent the object from being destroyed. > + * > + * Depending on the use case, one protection or the other is appropriate. In > + * most cases references are being protected by the destroy_rwsem. This allows > + * orderly destruction of the object because iommufd_object_destroy_user() will > + * wait for it to become unlocked. However, as a rwsem, it cannot be held across > + * a system call return. So cases that have longer term needs must switch > + * to the weaker users refcount_t. > + * > + * With users protection iommufd_object_destroy_user() will return -EBUSY to iommufd_object_destroy_user() returns false and iommufd_destroy retruns -EBUSY. > + * userspace and refuse to destroy the object. > + */ > +static inline void iommufd_ref_to_users(struct iommufd_object *obj) > +{ > + up_read(&obj->destroy_rwsem); > + /* iommufd_lock_obj() obtains users as well */ Do you have a way to check that put() is done in accordance, ie. we are not going to try up_read() the rwsem if this latter is not used anymore? > +} > +void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj); > +void iommufd_object_abort_and_destroy(struct iommufd_ctx *ictx, > + struct iommufd_object *obj); > +void iommufd_object_finalize(struct iommufd_ctx *ictx, > + struct iommufd_object *obj); > +bool iommufd_object_destroy_user(struct iommufd_ctx *ictx, > + struct iommufd_object *obj); > +struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx, > + size_t size, > + enum iommufd_object_type type); > + > +#define iommufd_object_alloc(ictx, ptr, type) \ > + container_of(_iommufd_object_alloc( \ > + ictx, \ > + sizeof(*(ptr)) + BUILD_BUG_ON_ZERO( \ > + offsetof(typeof(*(ptr)), \ > + obj) != 0), \ > + type), \ > + typeof(*(ptr)), obj) > + > +#endif > diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c > new file mode 100644 > index 00000000000000..3a705cadb85020 > --- /dev/null > +++ b/drivers/iommu/iommufd/main.c > @@ -0,0 +1,342 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* Copyright (C) 2021 Intel Corporation > + * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES > + * > + * iommufd provides control over the IOMMU HW objects created by IOMMU kernel > + * drivers. IOMMU HW objects revolve around IO page tables that map incoming DMA > + * addresses (IOVA) to CPU addresses. > + */ > +#define pr_fmt(fmt) "iommufd: " fmt > + > +#include <linux/file.h> > +#include <linux/fs.h> > +#include <linux/module.h> > +#include <linux/slab.h> > +#include <linux/miscdevice.h> > +#include <linux/mutex.h> > +#include <linux/bug.h> > +#include <uapi/linux/iommufd.h> > +#include <linux/iommufd.h> > + > +#include "iommufd_private.h" > + > +struct iommufd_object_ops { > + void (*destroy)(struct iommufd_object *obj); > +}; > +static const struct iommufd_object_ops iommufd_object_ops[]; > + > +struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx, > + size_t size, > + enum iommufd_object_type type) > +{ > + struct iommufd_object *obj; > + int rc; > + > + obj = kzalloc(size, GFP_KERNEL_ACCOUNT); > + if (!obj) > + return ERR_PTR(-ENOMEM); > + obj->type = type; > + init_rwsem(&obj->destroy_rwsem); > + refcount_set(&obj->users, 1); > + > + /* > + * Reserve an ID in the xarray but do not publish the pointer yet since > + * the caller hasn't initialized it yet. Once the pointer is published > + * in the xarray and visible to other threads we can't reliably destroy > + * it anymore, so the caller must complete all errorable operations > + * before calling iommufd_object_finalize(). > + */ > + rc = xa_alloc(&ictx->objects, &obj->id, XA_ZERO_ENTRY, > + xa_limit_32b, GFP_KERNEL_ACCOUNT); > + if (rc) > + goto out_free; > + return obj; > +out_free: > + kfree(obj); > + return ERR_PTR(rc); > +} > + > +/* > + * Allow concurrent access to the object. > + * > + * Once another thread can see the object pointer it can prevent object > + * destruction. Expect for special kernel-only objects there is no in-kernel way > + * to reliably destroy a single object. Thus all APIs that are creating objects > + * must use iommufd_object_abort() to handle their errors and only call > + * iommufd_object_finalize() once object creation cannot fail. > + */ > +void iommufd_object_finalize(struct iommufd_ctx *ictx, > + struct iommufd_object *obj) > +{ > + void *old; > + > + old = xa_store(&ictx->objects, obj->id, obj, GFP_KERNEL); > + /* obj->id was returned from xa_alloc() so the xa_store() cannot fail */ > + WARN_ON(old); > +} > + > +/* Undo _iommufd_object_alloc() if iommufd_object_finalize() was not called */ > +void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj) > +{ > + void *old; > + > + old = xa_erase(&ictx->objects, obj->id); > + WARN_ON(old); > + kfree(obj); > +} > + > +/* > + * Abort an object that has been fully initialized and needs destroy, but has > + * not been finalized. > + */ > +void iommufd_object_abort_and_destroy(struct iommufd_ctx *ictx, > + struct iommufd_object *obj) > +{ > + iommufd_object_ops[obj->type].destroy(obj); > + iommufd_object_abort(ictx, obj); > +} > + > +struct iommufd_object *iommufd_get_object(struct iommufd_ctx *ictx, u32 id, > + enum iommufd_object_type type) > +{ > + struct iommufd_object *obj; > + > + xa_lock(&ictx->objects); > + obj = xa_load(&ictx->objects, id); > + if (!obj || (type != IOMMUFD_OBJ_ANY && obj->type != type) || > + !iommufd_lock_obj(obj)) > + obj = ERR_PTR(-ENOENT); > + xa_unlock(&ictx->objects); > + return obj; > +} > + > +/* > + * The caller holds a users refcount and wants to destroy the object. Returns > + * true if the object was destroyed. In all cases the caller no longer has a > + * reference on obj. > + */ > +bool iommufd_object_destroy_user(struct iommufd_ctx *ictx, > + struct iommufd_object *obj) > +{ > + /* > + * The purpose of the destroy_rwsem is to ensure deterministic > + * destruction of objects used by external drivers and destroyed by this > + * function. Any temporary increment of the refcount must hold the read > + * side of this, such as during ioctl execution. > + */ > + down_write(&obj->destroy_rwsem); > + xa_lock(&ictx->objects); > + refcount_dec(&obj->users); > + if (!refcount_dec_if_one(&obj->users)) { > + xa_unlock(&ictx->objects); > + up_write(&obj->destroy_rwsem); > + return false; > + } > + __xa_erase(&ictx->objects, obj->id); > + xa_unlock(&ictx->objects); > + up_write(&obj->destroy_rwsem); > + > + iommufd_object_ops[obj->type].destroy(obj); > + kfree(obj); > + return true; > +} > + > +static int iommufd_destroy(struct iommufd_ucmd *ucmd) > +{ > + struct iommu_destroy *cmd = ucmd->cmd; > + struct iommufd_object *obj; > + > + obj = iommufd_get_object(ucmd->ictx, cmd->id, IOMMUFD_OBJ_ANY); > + if (IS_ERR(obj)) > + return PTR_ERR(obj); > + iommufd_ref_to_users(obj); > + /* See iommufd_ref_to_users() */ > + if (!iommufd_object_destroy_user(ucmd->ictx, obj)) > + return -EBUSY; > + return 0; > +} > + > +static int iommufd_fops_open(struct inode *inode, struct file *filp) > +{ > + struct iommufd_ctx *ictx; > + > + ictx = kzalloc(sizeof(*ictx), GFP_KERNEL_ACCOUNT); > + if (!ictx) > + return -ENOMEM; > + > + xa_init_flags(&ictx->objects, XA_FLAGS_ALLOC1 | XA_FLAGS_ACCOUNT); > + ictx->file = filp; > + filp->private_data = ictx; > + return 0; > +} > + > +static int iommufd_fops_release(struct inode *inode, struct file *filp) > +{ > + struct iommufd_ctx *ictx = filp->private_data; > + struct iommufd_object *obj; > + > + /* Destroy the graph from depth first */ I would suggest: destroy the leaf objects first thanks to the hierarchical user ref counting? or something alike > + while (!xa_empty(&ictx->objects)) { > + unsigned int destroyed = 0; > + unsigned long index; > + > + xa_for_each(&ictx->objects, index, obj) { > + /* > + * Since we are in release elevated users must come from > + * other objects holding the users. We will eventually the sentense sounds a bit cryptic to me. > + * destroy the object that holds this one and the next > + * pass will progress it. > + */ > + if (!refcount_dec_if_one(&obj->users)) > + continue; > + destroyed++; > + xa_erase(&ictx->objects, index); > + iommufd_object_ops[obj->type].destroy(obj); > + kfree(obj); Use iommufd_object_abort_and_destroy(obj) instead of the above 3 lines? > + } > + /* Bug related to users refcount */ > + if (WARN_ON(!destroyed)) > + break; > + } > + kfree(ictx); > + return 0; > +} > + > +union ucmd_buffer { > + struct iommu_destroy destroy; > +}; > + > +struct iommufd_ioctl_op { > + unsigned int size; > + unsigned int min_size; > + unsigned int ioctl_num; > + int (*execute)(struct iommufd_ucmd *ucmd); > +}; > + > +#define IOCTL_OP(_ioctl, _fn, _struct, _last) \ > + [_IOC_NR(_ioctl) - IOMMUFD_CMD_BASE] = { \ > + .size = sizeof(_struct) + \ > + BUILD_BUG_ON_ZERO(sizeof(union ucmd_buffer) < \ > + sizeof(_struct)), \ > + .min_size = offsetofend(_struct, _last), \ > + .ioctl_num = _ioctl, \ > + .execute = _fn, \ > + } > +static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = { > + IOCTL_OP(IOMMU_DESTROY, iommufd_destroy, struct iommu_destroy, id), > +}; > + > +static long iommufd_fops_ioctl(struct file *filp, unsigned int cmd, > + unsigned long arg) > +{ > + const struct iommufd_ioctl_op *op; > + struct iommufd_ucmd ucmd = {}; > + union ucmd_buffer buf; > + unsigned int nr; > + int ret; > + > + ucmd.ictx = filp->private_data; > + ucmd.ubuffer = (void __user *)arg; > + ret = get_user(ucmd.user_size, (u32 __user *)ucmd.ubuffer); > + if (ret) > + return ret; > + > + nr = _IOC_NR(cmd); > + if (nr < IOMMUFD_CMD_BASE || > + (nr - IOMMUFD_CMD_BASE) >= ARRAY_SIZE(iommufd_ioctl_ops)) > + return -ENOIOCTLCMD; > + op = &iommufd_ioctl_ops[nr - IOMMUFD_CMD_BASE]; > + if (op->ioctl_num != cmd) > + return -ENOIOCTLCMD; > + if (ucmd.user_size < op->min_size) > + return -EINVAL; > + > + ucmd.cmd = &buf; > + ret = copy_struct_from_user(ucmd.cmd, op->size, ucmd.ubuffer, > + ucmd.user_size); > + if (ret) > + return ret; > + ret = op->execute(&ucmd); > + return ret; > +} > + > +static const struct file_operations iommufd_fops = { > + .owner = THIS_MODULE, > + .open = iommufd_fops_open, > + .release = iommufd_fops_release, > + .unlocked_ioctl = iommufd_fops_ioctl, > +}; > + > +/** > + * iommufd_ctx_get - Get a context reference > + * @ictx: Context to get > + * > + * The caller must already hold a valid reference to ictx. > + */ > +void iommufd_ctx_get(struct iommufd_ctx *ictx) > +{ > + get_file(ictx->file); > +} > +EXPORT_SYMBOL_NS_GPL(iommufd_ctx_get, IOMMUFD); > + > +/** > + * iommufd_ctx_from_file - Acquires a reference to the iommufd context > + * @file: File to obtain the reference from > + * > + * Returns a pointer to the iommufd_ctx, otherwise ERR_PTR. The struct file > + * remains owned by the caller and the caller must still do fput. On success > + * the caller is responsible to call iommufd_ctx_put(). > + */ > +struct iommufd_ctx *iommufd_ctx_from_file(struct file *file) > +{ > + struct iommufd_ctx *ictx; > + > + if (file->f_op != &iommufd_fops) > + return ERR_PTR(-EBADFD); > + ictx = file->private_data; > + iommufd_ctx_get(ictx); > + return ictx; > +} > +EXPORT_SYMBOL_NS_GPL(iommufd_ctx_from_file, IOMMUFD); > + > +/** > + * iommufd_ctx_put - Put back a reference > + * @ictx: Context to put back > + */ > +void iommufd_ctx_put(struct iommufd_ctx *ictx) > +{ > + fput(ictx->file); > +} > +EXPORT_SYMBOL_NS_GPL(iommufd_ctx_put, IOMMUFD); > + > +static const struct iommufd_object_ops iommufd_object_ops[] = { > +}; > + > +static struct miscdevice iommu_misc_dev = { > + .minor = MISC_DYNAMIC_MINOR, > + .name = "iommu", > + .fops = &iommufd_fops, > + .nodename = "iommu", > + .mode = 0660, > +}; > + > +static int __init iommufd_init(void) > +{ > + int ret; > + > + ret = misc_register(&iommu_misc_dev); > + if (ret) > + return ret; > + return 0; > +} > + > +static void __exit iommufd_exit(void) > +{ > + misc_deregister(&iommu_misc_dev); > +} > + > +module_init(iommufd_init); > +module_exit(iommufd_exit); > + > +MODULE_DESCRIPTION("I/O Address Space Management for passthrough devices"); > +MODULE_LICENSE("GPL"); > diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h > new file mode 100644 > index 00000000000000..d1817472c27373 > --- /dev/null > +++ b/include/linux/iommufd.h > @@ -0,0 +1,31 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Copyright (C) 2021 Intel Corporation > + * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES > + */ > +#ifndef __LINUX_IOMMUFD_H > +#define __LINUX_IOMMUFD_H > + > +#include <linux/types.h> > +#include <linux/errno.h> > +#include <linux/err.h> > + > +struct iommufd_ctx; > +struct file; > + > +void iommufd_ctx_get(struct iommufd_ctx *ictx); > + > +#if IS_ENABLED(CONFIG_IOMMUFD) > +struct iommufd_ctx *iommufd_ctx_from_file(struct file *file); > +void iommufd_ctx_put(struct iommufd_ctx *ictx); > +#else /* !CONFIG_IOMMUFD */ > +static inline struct iommufd_ctx *iommufd_ctx_from_file(struct file *file) > +{ > + return ERR_PTR(-EOPNOTSUPP); > +} > + > +static inline void iommufd_ctx_put(struct iommufd_ctx *ictx) > +{ > +} > +#endif /* CONFIG_IOMMUFD */ > +#endif > diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h > new file mode 100644 > index 00000000000000..2ad06b27a35fe5 > --- /dev/null > +++ b/include/uapi/linux/iommufd.h > @@ -0,0 +1,55 @@ > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > +/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES. > + */ > +#ifndef _UAPI_IOMMUFD_H > +#define _UAPI_IOMMUFD_H > + > +#include <linux/types.h> > +#include <linux/ioctl.h> > + > +#define IOMMUFD_TYPE (';') > + > +/** > + * DOC: General ioctl format > + * > + * The ioctl interface follows a general format to allow for extensibility. Each > + * ioctl is passed in a structure pointer as the argument providing the size of > + * the structure in the first u32. The kernel checks that any structure space > + * beyond what it understands is 0. This allows userspace to use the backward > + * compatible portion while consistently using the newer, larger, structures. > + * > + * ioctls use a standard meaning for common errnos: > + * > + * - ENOTTY: The IOCTL number itself is not supported at all > + * - E2BIG: The IOCTL number is supported, but the provided structure has > + * non-zero in a part the kernel does not understand. > + * - EOPNOTSUPP: The IOCTL number is supported, and the structure is > + * understood, however a known field has a value the kernel does not > + * understand or support. > + * - EINVAL: Everything about the IOCTL was understood, but a field is not > + * correct. > + * - ENOENT: An ID or IOVA provided does not exist. > + * - ENOMEM: Out of memory. > + * - EOVERFLOW: Mathematics oveflowed. overflowed > + * > + * As well as additional errnos, within specific ioctls. > + */ > +enum { > + IOMMUFD_CMD_BASE = 0x80, > + IOMMUFD_CMD_DESTROY = IOMMUFD_CMD_BASE, > +}; > + > +/** > + * struct iommu_destroy - ioctl(IOMMU_DESTROY) > + * @size: sizeof(struct iommu_destroy) > + * @id: iommufd object ID to destroy. Can by any destroyable object type. > + * > + * Destroy any object held within iommufd. > + */ > +struct iommu_destroy { > + __u32 size; > + __u32 id; > +}; > +#define IOMMU_DESTROY _IO(IOMMUFD_TYPE, IOMMUFD_CMD_DESTROY) > + > +#endif Thanks Eric
