[Intel-gfx] [PATCH 06/10] vfio-iommufd: Allow iommufd to be used in place of a container fd

Jason Gunthorpe
2022-10-25T18:51:14Z

This makes VFIO_GROUP_SET_CONTAINER accept both a vfio container FD and an
iommufd.

In iommufd mode an IOAS will exist after the SET_CONTAINER, but it will
not be attached to any groups.

From a VFIO perspective this means that the VFIO_GROUP_GET_STATUS and
VFIO_GROUP_FLAGS_VIABLE works subtly differently. With the container FD
the iommu_group_claim_dma_owner() is done during SET_CONTAINER but for
IOMMFD this is done during VFIO_GROUP_GET_DEVICE_FD. Meaning that
VFIO_GROUP_FLAGS_VIABLE could be set but GET_DEVICE_FD will fail due to
viability.

As GET_DEVICE_FD can fail for many reasons already this is not expected to
be a meaningful difference.

Reorganize the tests for if the group has an assigned container or iommu
into a vfio_group_has_iommu() function and consolidate all the duplicated
WARN_ON's etc related to this.

Call container functions only if a container is actually present on the
group.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/vfio/Kconfig | 1 +
drivers/vfio/container.c | 7 ++--
drivers/vfio/vfio.h | 2 ++
drivers/vfio/vfio_main.c | 76 ++++++++++++++++++++++++++++++++--------
4 files changed, 69 insertions(+), 17 deletions(-)

diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
index 86c381ceb9a1e9..1118d322eec97d 100644
--- a/drivers/vfio/Kconfig
+++ b/drivers/vfio/Kconfig
@@ -2,6 +2,7 @@
menuconfig VFIO
tristate "VFIO Non-Privileged userspace driver framework"
select IOMMU_API
+ depends on IOMMUFD || !IOMMUFD
select VFIO_IOMMU_TYPE1 if MMU && (X86 || S390 || ARM || ARM64)
select INTERVAL_TREE
help
diff --git a/drivers/vfio/container.c b/drivers/vfio/container.c
index d97747dfb05d02..8772dad6808539 100644
--- a/drivers/vfio/container.c
+++ b/drivers/vfio/container.c
@@ -516,8 +516,11 @@ int vfio_group_use_container(struct vfio_group *group)
{
lockdep_assert_held(&group->group_lock);

- if (!group->container || !group->container->iommu_driver ||
- WARN_ON(!group->container_users))
+ /*
+ * The container fd has been assigned with VFIO_GROUP_SET_CONTAINER but
+ * VFIO_SET_IOMMU hasn't been done yet.
+ */
+ if (!group->container->iommu_driver)
return -EINVAL;

if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO))
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 247590334e14b0..985e13d52989ca 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -10,6 +10,7 @@
#include <linux/cdev.h>
#include <linux/module.h>

+struct iommufd_ctx;
struct iommu_group;
struct vfio_device;
struct vfio_container;
@@ -60,6 +61,7 @@ struct vfio_group {
struct kvm *kvm;
struct file *opened_file;
struct blocking_notifier_head notifier;
+ struct iommufd_ctx *iommufd;
};

/* events for the backend driver notify callback */
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index a8d1fbfcc3ddad..cf0ea744de931e 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -35,6 +35,7 @@
#include <linux/pm_runtime.h>
#include <linux/interval_tree.h>
#include <linux/iova_bitmap.h>
+#include <linux/iommufd.h>
#include "vfio.h"

#define DRIVER_VERSION "0.3"
@@ -665,6 +666,16 @@ EXPORT_SYMBOL_GPL(vfio_unregister_group_dev);
/*
* VFIO Group fd, /dev/vfio/$GROUP
*/
+static bool vfio_group_has_iommu(struct vfio_group *group)
+{
+ lockdep_assert_held(&group->group_lock);
+ if (!group->container)
+ WARN_ON(group->container_users);
+ else
+ WARN_ON(!group->container_users);
+ return group->container || group->iommufd;
+}
+
/*
* VFIO_GROUP_UNSET_CONTAINER should fail if there are other users or
* if there was no container to unset. Since the ioctl is called on
@@ -676,15 +687,21 @@ static int vfio_group_ioctl_unset_container(struct vfio_group *group)
int ret = 0;

mutex_lock(&group->group_lock);
- if (!group->container) {
+ if (!vfio_group_has_iommu(group)) {
ret = -EINVAL;
goto out_unlock;
}
- if (group->container_users != 1) {
- ret = -EBUSY;
- goto out_unlock;
+ if (group->container) {
+ if (group->container_users != 1) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+ vfio_group_detach_container(group);
+ }
+ if (group->iommufd) {
+ iommufd_ctx_put(group->iommufd);
+ group->iommufd = NULL;
}
- vfio_group_detach_container(group);

out_unlock:
mutex_unlock(&group->group_lock);
@@ -695,6 +712,7 @@ static int vfio_group_ioctl_set_container(struct vfio_group *group,
int __user *arg)
{
struct vfio_container *container;
+ struct iommufd_ctx *iommufd;
struct fd f;
int ret;
int fd;
@@ -707,7 +725,7 @@ static int vfio_group_ioctl_set_container(struct vfio_group *group,
return -EBADF;

mutex_lock(&group->group_lock);
- if (group->container || WARN_ON(group->container_users)) {
+ if (vfio_group_has_iommu(group)) {
ret = -EINVAL;
goto out_unlock;
}
@@ -717,12 +735,23 @@ static int vfio_group_ioctl_set_container(struct vfio_group *group,
}

container = vfio_container_from_file(f.file);
- ret = -EINVAL;
if (container) {
ret = vfio_container_attach_group(container, group);
goto out_unlock;
}

+ iommufd = iommufd_ctx_from_file(f.file);
+ if (!IS_ERR(iommufd)) {
+ u32 ioas_id;
+
+ group->iommufd = iommufd;
+ ret = iommufd_vfio_compat_ioas_id(iommufd, &ioas_id);
+ goto out_unlock;
+ }
+
+ /* The FD passed is not recognized. */
+ ret = -EBADF;
+
out_unlock:
mutex_unlock(&group->group_lock);
fdput(f);
@@ -752,9 +781,16 @@ static int vfio_device_first_open(struct vfio_device *device)
* it during close_device.
*/
mutex_lock(&device->group->group_lock);
- ret = vfio_group_use_container(device->group);
- if (ret)
+ if (!vfio_group_has_iommu(device->group)) {
+ ret = -EINVAL;
goto err_module_put;
+ }
+
+ if (device->group->container) {
+ ret = vfio_group_use_container(device->group);
+ if (ret)
+ goto err_module_put;
+ }

device->kvm = device->group->kvm;
if (device->ops->open_device) {
@@ -762,14 +798,16 @@ static int vfio_device_first_open(struct vfio_device *device)
if (ret)
goto err_container;
}
- vfio_device_container_register(device);
+ if (device->group->container)
+ vfio_device_container_register(device);
mutex_unlock(&device->group->group_lock);
return 0;

err_container:
- vfio_group_unuse_container(device->group);
-err_module_put:
+ if (device->group->container)
+ vfio_group_unuse_container(device->group);
device->kvm = NULL;
+err_module_put:
mutex_unlock(&device->group->group_lock);
module_put(device->dev->driver->owner);
return ret;
@@ -780,11 +818,13 @@ static void vfio_device_last_close(struct vfio_device *device)
lockdep_assert_held(&device->dev_set->lock);

mutex_lock(&device->group->group_lock);
- vfio_device_container_unregister(device);
+ if (device->group->container)
+ vfio_device_container_unregister(device);
if (device->ops->close_device)
device->ops->close_device(device);
device->kvm = NULL;
- vfio_group_unuse_container(device->group);
+ if (device->group->container)
+ vfio_group_unuse_container(device->group);
mutex_unlock(&device->group->group_lock);
module_put(device->dev->driver->owner);
}
@@ -900,7 +940,7 @@ static int vfio_group_ioctl_get_status(struct vfio_group *group,
return -ENODEV;
}

- if (group->container)
+ if (group->container || group->iommufd)
status.flags |= VFIO_GROUP_FLAGS_CONTAINER_SET |
VFIO_GROUP_FLAGS_VIABLE;
else if (!iommu_group_dma_owner_claimed(group->iommu_group))
@@ -983,6 +1023,10 @@ static int vfio_group_fops_release(struct inode *inode, struct file *filep)
WARN_ON(group->notifier.head);
if (group->container)
vfio_group_detach_container(group);
+ if (group->iommufd) {
+ iommufd_ctx_put(group->iommufd);
+ group->iommufd = NULL;
+ }
group->opened_file = NULL;
mutex_unlock(&group->group_lock);
return 0;
@@ -1879,6 +1923,8 @@ static void __exit vfio_cleanup(void)
module_init(vfio_init);
module_exit(vfio_cleanup);

+MODULE_IMPORT_NS(IOMMUFD);
+MODULE_IMPORT_NS(IOMMUFD_VFIO);
MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR(DRIVER_AUTHOR);
--
2.38.0