From c68ea0d00ad82428154aed890ec9f793e460fa1c Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Fri, 24 Sep 2021 17:56:57 +0200
Subject: [PATCH] vfio: simplify iommu group allocation for mediated devices
References: bsc#1205701
Patch-mainline: v5.16-rc1
Git-commit: c68ea0d00ad82428154aed890ec9f793e460fa1c
Reuse the logic in vfio_noiommu_group_alloc to allocate a fake
single-device iommu group for mediated devices by factoring out a common
function, and replacing the noiommu boolean field in struct vfio_group
with an enum to distinguish the three different kinds of groups.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-8-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
drivers/s390/crypto/vfio_ap_ops.c | 2 +-
drivers/vfio/mdev/mdev_driver.c | 45 ++-------------
drivers/vfio/mdev/vfio_mdev.c | 2 +-
drivers/vfio/vfio.c | 92 ++++++++++++++++++++++---------
include/linux/vfio.h | 1 +
samples/vfio-mdev/mbochs.c | 2 +-
samples/vfio-mdev/mdpy.c | 2 +-
samples/vfio-mdev/mtty.c | 2 +-
8 files changed, 76 insertions(+), 72 deletions(-)
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 118939a7729a..24755d1aedd5 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -351,7 +351,7 @@ static int vfio_ap_mdev_probe(struct mdev_device *mdev)
list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
mutex_unlock(&matrix_dev->lock);
- ret = vfio_register_group_dev(&matrix_mdev->vdev);
+ ret = vfio_register_emulated_iommu_dev(&matrix_mdev->vdev);
if (ret)
goto err_list;
dev_set_drvdata(&mdev->dev, matrix_mdev);
diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
index e2cb1ff56f6c..7927ed4f1711 100644
--- a/drivers/vfio/mdev/mdev_driver.c
+++ b/drivers/vfio/mdev/mdev_driver.c
@@ -13,60 +13,23 @@
#include "mdev_private.h"
-static int mdev_attach_iommu(struct mdev_device *mdev)
-{
- int ret;
- struct iommu_group *group;
-
- group = iommu_group_alloc();
- if (IS_ERR(group))
- return PTR_ERR(group);
-
- ret = iommu_group_add_device(group, &mdev->dev);
- if (!ret)
- dev_info(&mdev->dev, "MDEV: group_id = %d\n",
- iommu_group_id(group));
-
- iommu_group_put(group);
- return ret;
-}
-
-static void mdev_detach_iommu(struct mdev_device *mdev)
-{
- iommu_group_remove_device(&mdev->dev);
- dev_info(&mdev->dev, "MDEV: detaching iommu\n");
-}
-
static int mdev_probe(struct device *dev)
{
struct mdev_driver *drv =
container_of(dev->driver, struct mdev_driver, driver);
- struct mdev_device *mdev = to_mdev_device(dev);
- int ret;
- ret = mdev_attach_iommu(mdev);
- if (ret)
- return ret;
-
- if (drv->probe) {
- ret = drv->probe(mdev);
- if (ret)
- mdev_detach_iommu(mdev);
- }
-
- return ret;
+ if (!drv->probe)
+ return 0;
+ return drv->probe(to_mdev_device(dev));
}
static void mdev_remove(struct device *dev)
{
struct mdev_driver *drv =
container_of(dev->driver, struct mdev_driver, driver);
- struct mdev_device *mdev = to_mdev_device(dev);
if (drv->remove)
- drv->remove(mdev);
-
- mdev_detach_iommu(mdev);
+ drv->remove(to_mdev_device(dev));
}
static int mdev_match(struct device *dev, struct device_driver *drv)
diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
index 7a9883048216..a90e24b0c851 100644
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ b/drivers/vfio/mdev/vfio_mdev.c
@@ -119,7 +119,7 @@ static int vfio_mdev_probe(struct mdev_device *mdev)
return -ENOMEM;
vfio_init_group_dev(vdev, &mdev->dev, &vfio_mdev_dev_ops);
- ret = vfio_register_group_dev(vdev);
+ ret = vfio_register_emulated_iommu_dev(vdev);
if (ret)
goto out_uninit;
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 23eaebd2e28c..2508c8c39840 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -67,6 +67,30 @@ struct vfio_unbound_dev {
struct list_head unbound_next;
};
+enum vfio_group_type {
+ /*
+ * Physical device with IOMMU backing.
+ */
+ VFIO_IOMMU,
+
+ /*
+ * Virtual device without IOMMU backing. The VFIO core fakes up an
+ * iommu_group as the iommu_group sysfs interface is part of the
+ * userspace ABI. The user of these devices must not be able to
+ * directly trigger unmediated DMA.
+ */
+ VFIO_EMULATED_IOMMU,
+
+ /*
+ * Physical device without IOMMU backing. The VFIO core fakes up an
+ * iommu_group as the iommu_group sysfs interface is part of the
+ * userspace ABI. Users can trigger unmediated DMA by the device,
+ * usage is highly dangerous, requires an explicit opt-in and will
+ * taint the kernel.
+ */
+ VFIO_NO_IOMMU,
+};
+
struct vfio_group {
struct kref kref;
int minor;
@@ -83,7 +107,7 @@ struct vfio_group {
struct mutex unbound_lock;
atomic_t opened;
wait_queue_head_t container_q;
- bool noiommu;
+ enum vfio_group_type type;
unsigned int dev_counter;
struct kvm *kvm;
struct blocking_notifier_head notifier;
@@ -336,7 +360,7 @@ static void vfio_group_unlock_and_free(struct vfio_group *group)
* Group objects - create, release, get, put, search
*/
static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
- bool noiommu)
+ enum vfio_group_type type)
{
struct vfio_group *group, *tmp;
struct device *dev;
@@ -355,7 +379,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
atomic_set(&group->opened, 0);
init_waitqueue_head(&group->container_q);
group->iommu_group = iommu_group;
- group->noiommu = noiommu;
+ group->type = type;
BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier);
group->nb.notifier_call = vfio_iommu_group_notifier;
@@ -391,8 +415,8 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
}
dev = device_create(vfio.class, NULL,
- MKDEV(MAJOR(vfio.group_devt), minor),
- group, "%s%d", group->noiommu ? "noiommu-" : "",
+ MKDEV(MAJOR(vfio.group_devt), minor), group, "%s%d",
+ group->type == VFIO_NO_IOMMU ? "noiommu-" : "",
iommu_group_id(iommu_group));
if (IS_ERR(dev)) {
vfio_free_group_minor(minor);
@@ -778,8 +802,8 @@ void vfio_uninit_group_dev(struct vfio_device *device)
}
EXPORT_SYMBOL_GPL(vfio_uninit_group_dev);
-#ifdef CONFIG_VFIO_NOIOMMU
-static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev)
+static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
+ enum vfio_group_type type)
{
struct iommu_group *iommu_group;
struct vfio_group *group;
@@ -794,7 +818,7 @@ static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev)
if (ret)
goto out_put_group;
- group = vfio_create_group(iommu_group, true);
+ group = vfio_create_group(iommu_group, type);
if (IS_ERR(group)) {
ret = PTR_ERR(group);
goto out_remove_device;
@@ -808,7 +832,6 @@ static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev)
iommu_group_put(iommu_group);
return ERR_PTR(ret);
}
-#endif
static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
{
@@ -824,7 +847,7 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
* bus. Taint the kernel because we're about to give a DMA
* capable device to a user without IOMMU protection.
*/
- group = vfio_noiommu_group_alloc(dev);
+ group = vfio_noiommu_group_alloc(dev, VFIO_NO_IOMMU);
if (!IS_ERR(group)) {
add_taint(TAINT_USER, LOCKDEP_STILL_OK);
dev_warn(dev, "Adding kernel taint for vfio-noiommu group on device\n");
@@ -841,7 +864,7 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
goto out_put;
/* a newly created vfio_group keeps the reference. */
- group = vfio_create_group(iommu_group, false);
+ group = vfio_create_group(iommu_group, VFIO_IOMMU);
if (IS_ERR(group))
goto out_put;
return group;
@@ -851,10 +874,13 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
return group;
}
-int vfio_register_group_dev(struct vfio_device *device)
+static int __vfio_register_dev(struct vfio_device *device,
+ struct vfio_group *group)
{
struct vfio_device *existing_device;
- struct vfio_group *group;
+
+ if (IS_ERR(group))
+ return PTR_ERR(group);
/*
* If the driver doesn't specify a set then the device is added to a
@@ -863,16 +889,13 @@ int vfio_register_group_dev(struct vfio_device *device)
if (!device->dev_set)
vfio_assign_device_set(device, device);
- group = vfio_group_find_or_alloc(device->dev);
- if (IS_ERR(group))
- return PTR_ERR(group);
-
existing_device = vfio_group_get_device(group, device->dev);
if (existing_device) {
dev_WARN(device->dev, "Device already exists on group %d\n",
iommu_group_id(group->iommu_group));
vfio_device_put(existing_device);
- if (group->noiommu)
+ if (group->type == VFIO_NO_IOMMU ||
+ group->type == VFIO_EMULATED_IOMMU)
iommu_group_remove_device(device->dev);
vfio_group_put(group);
return -EBUSY;
@@ -891,8 +914,25 @@ int vfio_register_group_dev(struct vfio_device *device)
return 0;
}
+
+int vfio_register_group_dev(struct vfio_device *device)
+{
+ return __vfio_register_dev(device,
+ vfio_group_find_or_alloc(device->dev));
+}
EXPORT_SYMBOL_GPL(vfio_register_group_dev);
+/*
+ * Register a virtual device without IOMMU backing. The user of this
+ * device must not be able to directly trigger unmediated DMA.
+ */
+int vfio_register_emulated_iommu_dev(struct vfio_device *device)
+{
+ return __vfio_register_dev(device,
+ vfio_noiommu_group_alloc(device->dev, VFIO_EMULATED_IOMMU));
+}
+EXPORT_SYMBOL_GPL(vfio_register_emulated_iommu_dev);
+
/**
* Get a reference to the vfio_device for a device. Even if the
* caller thinks they own the device, they could be racing with a
@@ -1019,7 +1059,7 @@ void vfio_unregister_group_dev(struct vfio_device *device)
if (list_empty(&group->device_list))
wait_event(group->container_q, !group->container);
- if (group->noiommu)
+ if (group->type == VFIO_NO_IOMMU || group->type == VFIO_EMULATED_IOMMU)
iommu_group_remove_device(device->dev);
/* Matches the get in vfio_register_group_dev() */
@@ -1368,7 +1408,7 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)
if (atomic_read(&group->container_users))
return -EINVAL;
- if (group->noiommu && !capable(CAP_SYS_RAWIO))
+ if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO))
return -EPERM;
f = fdget(container_fd);
@@ -1388,7 +1428,7 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)
/* Real groups and fake groups cannot mix */
if (!list_empty(&container->group_list) &&
- container->noiommu != group->noiommu) {
+ container->noiommu != (group->type == VFIO_NO_IOMMU)) {
ret = -EPERM;
goto unlock_out;
}
@@ -1402,7 +1442,7 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)
}
group->container = container;
- container->noiommu = group->noiommu;
+ container->noiommu = (group->type == VFIO_NO_IOMMU);
list_add(&group->container_next, &container->group_list);
/* Get a reference on the container and mark a user within the group */
@@ -1426,7 +1466,7 @@ static int vfio_group_add_container_user(struct vfio_group *group)
if (!atomic_inc_not_zero(&group->container_users))
return -EINVAL;
- if (group->noiommu) {
+ if (group->type == VFIO_NO_IOMMU) {
atomic_dec(&group->container_users);
return -EPERM;
}
@@ -1451,7 +1491,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
!group->container->iommu_driver || !vfio_group_viable(group))
return -EINVAL;
- if (group->noiommu && !capable(CAP_SYS_RAWIO))
+ if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO))
return -EPERM;
device = vfio_device_get_from_name(group, buf);
@@ -1498,7 +1538,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
fd_install(fdno, filep);
- if (group->noiommu)
+ if (group->type == VFIO_NO_IOMMU)
dev_warn(device->dev, "vfio-noiommu device opened by user "
"(%s:%d)\n", current->comm, task_pid_nr(current));
return fdno;
@@ -1594,7 +1634,7 @@ static int vfio_group_fops_open(struct inode *inode, struct file *filep)
if (!group)
return -ENODEV;
- if (group->noiommu && !capable(CAP_SYS_RAWIO)) {
+ if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO)) {
vfio_group_put(group);
return -EPERM;
}
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index f7083c2fd0d0..bbe293008626 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -75,6 +75,7 @@ void vfio_init_group_dev(struct vfio_device *device, struct device *dev,
const struct vfio_device_ops *ops);
void vfio_uninit_group_dev(struct vfio_device *device);
int vfio_register_group_dev(struct vfio_device *device);
+int vfio_register_emulated_iommu_dev(struct vfio_device *device);
void vfio_unregister_group_dev(struct vfio_device *device);
extern struct vfio_device *vfio_device_get_from_dev(struct device *dev);
extern void vfio_device_put(struct vfio_device *device);
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index c313ab4d1f4e..cd41bec5fdeb 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -553,7 +553,7 @@ static int mbochs_probe(struct mdev_device *mdev)
mbochs_create_config_space(mdev_state);
mbochs_reset(mdev_state);
- ret = vfio_register_group_dev(&mdev_state->vdev);
+ ret = vfio_register_emulated_iommu_dev(&mdev_state->vdev);
if (ret)
goto err_mem;
dev_set_drvdata(&mdev->dev, mdev_state);
diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index 8d1a80a0722a..fe5d43e797b6 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -258,7 +258,7 @@ static int mdpy_probe(struct mdev_device *mdev)
mdpy_count++;
- ret = vfio_register_group_dev(&mdev_state->vdev);
+ ret = vfio_register_emulated_iommu_dev(&mdev_state->vdev);
if (ret)
goto err_mem;
dev_set_drvdata(&mdev->dev, mdev_state);
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index 5983cdb16e3d..a0e1a469bd47 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -741,7 +741,7 @@ static int mtty_probe(struct mdev_device *mdev)
mtty_create_config_space(mdev_state);
- ret = vfio_register_group_dev(&mdev_state->vdev);
+ ret = vfio_register_emulated_iommu_dev(&mdev_state->vdev);
if (ret)
goto err_vconfig;
dev_set_drvdata(&mdev->dev, mdev_state);
--
2.39.2