| Message ID | 11-v3-50561e12d92b+313-vfio_iommufd_jgg@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Connect VFIO to IOMMUFD | expand |
On Wed, 16 Nov 2022 17:05:36 -0400 Jason Gunthorpe <jgg@nvidia.com> wrote: > 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. > > Tested-by: Nicolin Chen <nicolinc@nvidia.com> > Tested-by: Yi Liu <yi.l.liu@intel.com> > Tested-by: Lixiao Yang <lixiao.yang@intel.com> > Tested-by: Matthew Rosato <mjrosato@linux.ibm.com> > Tested-by: Yu He <yu.he@intel.com> > Reviewed-by: Kevin Tian <kevin.tian@intel.com> > Reviewed-by: Yi Liu <yi.l.liu@intel.com> > Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> > --- > drivers/iommu/iommufd/Kconfig | 12 ++++++++++++ > drivers/iommu/iommufd/main.c | 36 +++++++++++++++++++++++++++++++++++ > 2 files changed, 48 insertions(+) > > diff --git a/drivers/iommu/iommufd/Kconfig b/drivers/iommu/iommufd/Kconfig > index 399a2edeaef6de..f387f803dc6f7f 100644 > --- a/drivers/iommu/iommufd/Kconfig > +++ b/drivers/iommu/iommufd/Kconfig > @@ -12,6 +12,18 @@ 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. > + > + Unless testing IOMMUFD say N here. > + "Unless testing..." alone is a bit more subtle that I thought we were discussing. I was expecting something more like: 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. Thanks, Alex
On Thu, Nov 17, 2022 at 01:34:17PM -0700, Alex Williamson wrote: > > +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. > > + > > + Unless testing IOMMUFD say N here. > > + > > "Unless testing..." alone is a bit more subtle that I thought we were > discussing. I was expecting something more like: > > 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. Done, thanks Jason
diff --git a/drivers/iommu/iommufd/Kconfig b/drivers/iommu/iommufd/Kconfig index 399a2edeaef6de..f387f803dc6f7f 100644 --- a/drivers/iommu/iommufd/Kconfig +++ b/drivers/iommu/iommufd/Kconfig @@ -12,6 +12,18 @@ 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. + + Unless testing IOMMUFD say N here. + config IOMMUFD_TEST bool "IOMMU Userspace API Test support" depends on RUNTIME_TESTING_MENU diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index ab3fa05f38505d..1eeb326f74f005 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -18,6 +18,7 @@ #include <uapi/linux/iommufd.h> #include <linux/iommufd.h> +#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; @@ -395,6 +407,15 @@ 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; @@ -402,18 +423,33 @@ 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");