/dev/iommu aims to provide a unified interface for managing I/O address spaces for devices assigned to userspace. This patch adds the initial framework to create a /dev/iommu node. Each open of this node returns an iommufd. And this fd is the handle for userspace to initiate its I/O address space management. One open: - We call this feature as IOMMUFD in Kconfig in this RFC. However this name is not clear enough to indicate its purpose to user. Back to 2010 vfio even introduced a /dev/uiommu [1] as the predecessor of its container concept. Is that a better name? Appreciate opinions here. [1] https://lore.kernel.org/kvm/4c0eb470.1HMjondO00NIvFM6%25pugs@xxxxxxxxx/ Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx> --- drivers/iommu/Kconfig | 1 + drivers/iommu/Makefile | 1 + drivers/iommu/iommufd/Kconfig | 11 ++++ drivers/iommu/iommufd/Makefile | 2 + drivers/iommu/iommufd/iommufd.c | 112 ++++++++++++++++++++++++++++++++ 5 files changed, 127 insertions(+) create mode 100644 drivers/iommu/iommufd/Kconfig create mode 100644 drivers/iommu/iommufd/Makefile create mode 100644 drivers/iommu/iommufd/iommufd.c diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index 07b7c25cbed8..a83ce0acd09d 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -136,6 +136,7 @@ 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 c0fb0ba88143..719c799f23ad 100644 --- a/drivers/iommu/Makefile +++ b/drivers/iommu/Makefile @@ -29,3 +29,4 @@ obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o obj-$(CONFIG_IOMMU_SVA_LIB) += iommu-sva-lib.o io-pgfault.o obj-$(CONFIG_SPRD_IOMMU) += sprd-iommu.o +obj-$(CONFIG_IOMMUFD) += iommufd/ diff --git a/drivers/iommu/iommufd/Kconfig b/drivers/iommu/iommufd/Kconfig new file mode 100644 index 000000000000..9fb7769a815d --- /dev/null +++ b/drivers/iommu/iommufd/Kconfig @@ -0,0 +1,11 @@ +# SPDX-License-Identifier: GPL-2.0-only +config IOMMUFD + tristate "I/O Address Space management framework for passthrough devices" + select IOMMU_API + default n + help + provides unified I/O address space management framework for + isolating untrusted DMAs via devices which are passed through + to userspace drivers. + + If you don't know what to do here, say N. diff --git a/drivers/iommu/iommufd/Makefile b/drivers/iommu/iommufd/Makefile new file mode 100644 index 000000000000..54381a01d003 --- /dev/null +++ b/drivers/iommu/iommufd/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_IOMMUFD) += iommufd.o diff --git a/drivers/iommu/iommufd/iommufd.c b/drivers/iommu/iommufd/iommufd.c new file mode 100644 index 000000000000..710b7e62988b --- /dev/null +++ b/drivers/iommu/iommufd/iommufd.c @@ -0,0 +1,112 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * I/O Address Space Management for passthrough devices + * + * Copyright (C) 2021 Intel Corporation + * + * Author: Liu Yi L <yi.l.liu@xxxxxxxxx> + */ + +#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/iommu.h> + +/* Per iommufd */ +struct iommufd_ctx { + refcount_t refs; +}; + +static int iommufd_fops_open(struct inode *inode, struct file *filep) +{ + struct iommufd_ctx *ictx; + int ret = 0; + + ictx = kzalloc(sizeof(*ictx), GFP_KERNEL); + if (!ictx) + return -ENOMEM; + + refcount_set(&ictx->refs, 1); + filep->private_data = ictx; + + return ret; +} + +static void iommufd_ctx_put(struct iommufd_ctx *ictx) +{ + if (refcount_dec_and_test(&ictx->refs)) + kfree(ictx); +} + +static int iommufd_fops_release(struct inode *inode, struct file *filep) +{ + struct iommufd_ctx *ictx = filep->private_data; + + filep->private_data = NULL; + + iommufd_ctx_put(ictx); + + return 0; +} + +static long iommufd_fops_unl_ioctl(struct file *filep, + unsigned int cmd, unsigned long arg) +{ + struct iommufd_ctx *ictx = filep->private_data; + long ret = -EINVAL; + + if (!ictx) + return ret; + + switch (cmd) { + default: + pr_err_ratelimited("unsupported cmd %u\n", cmd); + break; + } + return ret; +} + +static const struct file_operations iommufd_fops = { + .owner = THIS_MODULE, + .open = iommufd_fops_open, + .release = iommufd_fops_release, + .unlocked_ioctl = iommufd_fops_unl_ioctl, +}; + +static struct miscdevice iommu_misc_dev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "iommu", + .fops = &iommufd_fops, + .nodename = "iommu", + .mode = 0666, +}; + +static int __init iommufd_init(void) +{ + int ret; + + ret = misc_register(&iommu_misc_dev); + if (ret) { + pr_err("failed to register misc device\n"); + return ret; + } + + return 0; +} + +static void __exit iommufd_exit(void) +{ + misc_deregister(&iommu_misc_dev); +} + +module_init(iommufd_init); +module_exit(iommufd_exit); + +MODULE_AUTHOR("Liu Yi L <yi.l.liu@xxxxxxxxx>"); +MODULE_DESCRIPTION("I/O Address Space Management for passthrough devices"); +MODULE_LICENSE("GPL v2"); -- 2.25.1
