From 01f70cbb26eadb5959344598977cb7159948263a Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Tue, 29 Nov 2022 16:31:55 -0400 Subject: [PATCH] iommufd: Allow iommufd to supply /dev/vfio/vfio If the VFIO container is compiled out, give a kconfig option for iommufd to provide the miscdev node with the same name and permissions as vfio uses. The compatibility node supports the same ioctls as VFIO and automatically enables the VFIO compatible pinned page accounting mode. Link: https://lore.kernel.org/r/10-v4-42cd2eb0e3eb+335a-vfio_iommufd_jgg@nvidia.com Reviewed-by: Kevin Tian Reviewed-by: Yi Liu Reviewed-by: Alex Williamson Tested-by: Alex Williamson Tested-by: Nicolin Chen Tested-by: Yi Liu Tested-by: Lixiao Yang Tested-by: Matthew Rosato Tested-by: Yu He Signed-off-by: Jason Gunthorpe --- drivers/iommu/iommufd/Kconfig | 20 +++++++++++++++++++ drivers/iommu/iommufd/main.c | 36 +++++++++++++++++++++++++++++++++++ 2 files changed, 56 insertions(+) diff --git a/drivers/iommu/iommufd/Kconfig b/drivers/iommu/iommufd/Kconfig index 871244f2443f..8306616b6d81 100644 --- a/drivers/iommu/iommufd/Kconfig +++ b/drivers/iommu/iommufd/Kconfig @@ -12,6 +12,26 @@ config IOMMUFD If you don't know what to do here, say N. if IOMMUFD +config IOMMUFD_VFIO_CONTAINER + bool "IOMMUFD provides the VFIO container /dev/vfio/vfio" + depends on VFIO && !VFIO_CONTAINER + default VFIO && !VFIO_CONTAINER + help + IOMMUFD will provide /dev/vfio/vfio instead of VFIO. This relies on + IOMMUFD providing compatibility emulation to give the same ioctls. + It provides an option to build a kernel with legacy VFIO components + removed. + + IOMMUFD VFIO container emulation is known to lack certain features + of the native VFIO container, such as no-IOMMU support, peer-to-peer + DMA mapping, PPC IOMMU support, as well as other potentially + undiscovered gaps. This option is currently intended for the + purpose of testing IOMMUFD with unmodified userspace supporting VFIO + and making use of the Type1 VFIO IOMMU backend. General purpose + enabling of this option is currently discouraged. + + Unless testing IOMMUFD, say N here. + config IOMMUFD_TEST bool "IOMMU Userspace API Test support" depends on DEBUG_KERNEL diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index bcb463e58100..083e6fcbe10a 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -18,6 +18,7 @@ #include #include +#include "io_pagetable.h" #include "iommufd_private.h" #include "iommufd_test.h" @@ -25,6 +26,7 @@ struct iommufd_object_ops { void (*destroy)(struct iommufd_object *obj); }; static const struct iommufd_object_ops iommufd_object_ops[]; +static struct miscdevice vfio_misc_dev; struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx, size_t size, @@ -170,6 +172,16 @@ static int iommufd_fops_open(struct inode *inode, struct file *filp) if (!ictx) return -ENOMEM; + /* + * For compatibility with VFIO when /dev/vfio/vfio is opened we default + * to the same rlimit accounting as vfio uses. + */ + if (IS_ENABLED(CONFIG_IOMMUFD_VFIO_CONTAINER) && + filp->private_data == &vfio_misc_dev) { + ictx->account_mode = IOPT_PAGES_ACCOUNT_MM; + pr_info_once("IOMMUFD is providing /dev/vfio/vfio, not VFIO.\n"); + } + xa_init_flags(&ictx->objects, XA_FLAGS_ALLOC1 | XA_FLAGS_ACCOUNT); ictx->file = filp; filp->private_data = ictx; @@ -400,6 +412,15 @@ static struct miscdevice iommu_misc_dev = { .mode = 0660, }; + +static struct miscdevice vfio_misc_dev = { + .minor = VFIO_MINOR, + .name = "vfio", + .fops = &iommufd_fops, + .nodename = "vfio/vfio", + .mode = 0666, +}; + static int __init iommufd_init(void) { int ret; @@ -407,18 +428,33 @@ static int __init iommufd_init(void) ret = misc_register(&iommu_misc_dev); if (ret) return ret; + + if (IS_ENABLED(CONFIG_IOMMUFD_VFIO_CONTAINER)) { + ret = misc_register(&vfio_misc_dev); + if (ret) + goto err_misc; + } iommufd_test_init(); return 0; +err_misc: + misc_deregister(&iommu_misc_dev); + return ret; } static void __exit iommufd_exit(void) { iommufd_test_exit(); + if (IS_ENABLED(CONFIG_IOMMUFD_VFIO_CONTAINER)) + misc_deregister(&vfio_misc_dev); misc_deregister(&iommu_misc_dev); } module_init(iommufd_init); module_exit(iommufd_exit); +#if IS_ENABLED(CONFIG_IOMMUFD_VFIO_CONTAINER) +MODULE_ALIAS_MISCDEV(VFIO_MINOR); +MODULE_ALIAS("devname:vfio/vfio"); +#endif MODULE_DESCRIPTION("I/O Address Space Management for passthrough devices"); MODULE_LICENSE("GPL");