[PATCH v2 06/19] iommufd/viommu: Add IOMMU_VIOMMU_SET/UNSET_VDEV_ID ioctl

Nicolin Chen
2024-08-27T17:13:40Z

Introduce a pair of new ioctls to set/unset a per-viommu virtual device id
that should be linked to a physical device id via an idev pointer.

Continue the support IOMMU_VIOMMU_TYPE_DEFAULT for a core-managed viommu.
Provide a lookup function for drivers to load device pointer by a virtual
device id.

Add a rw_semaphore protection around the vdev_id list. Any future ioctl
handlers that potentially access the list must grab the lock too.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
drivers/iommu/iommufd/device.c | 12 +++
drivers/iommu/iommufd/iommufd_private.h | 21 ++++
drivers/iommu/iommufd/main.c | 6 ++
drivers/iommu/iommufd/viommu.c | 121 ++++++++++++++++++++++++
include/uapi/linux/iommufd.h | 40 ++++++++
5 files changed, 200 insertions(+)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 5fd3dd420290..3ad759971b32 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -136,6 +136,18 @@ void iommufd_device_destroy(struct iommufd_object *obj)
struct iommufd_device *idev =
container_of(obj, struct iommufd_device, obj);

+ /* Unlocked since there should be no race in a destroy() */
+ if (idev->vdev_id) {
+ struct iommufd_vdev_id *vdev_id = idev->vdev_id;
+ struct iommufd_viommu *viommu = vdev_id->viommu;
+ struct iommufd_vdev_id *old;
+
+ old = xa_cmpxchg(&viommu->vdev_ids, vdev_id->id, vdev_id, NULL,
+ GFP_KERNEL);
+ WARN_ON(old != vdev_id);
+ kfree(vdev_id);
+ idev->vdev_id = NULL;
+ }
iommu_device_release_dma_owner(idev->dev);
iommufd_put_group(idev->igroup);
if (!iommufd_selftest_is_mock_dev(idev->dev))
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 1f2a1c133b9a..2c6e168c5300 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -416,6 +416,7 @@ struct iommufd_device {
struct iommufd_object obj;
struct iommufd_ctx *ictx;
struct iommufd_group *igroup;
+ struct iommufd_vdev_id *vdev_id;
struct list_head group_item;
/* always the physical device */
struct device *dev;
@@ -533,11 +534,31 @@ struct iommufd_viommu {
struct iommufd_ctx *ictx;
struct iommufd_hwpt_paging *hwpt;

+ /* The locking order is vdev_ids_rwsem -> igroup::lock */
+ struct rw_semaphore vdev_ids_rwsem;
+ struct xarray vdev_ids;
+
unsigned int type;
};

+struct iommufd_vdev_id {
+ struct iommufd_viommu *viommu;
+ struct iommufd_device *idev;
+ u64 id;
+};
+
+static inline struct iommufd_viommu *
+iommufd_get_viommu(struct iommufd_ucmd *ucmd, u32 id)
+{
+ return container_of(iommufd_get_object(ucmd->ictx, id,
+ IOMMUFD_OBJ_VIOMMU),
+ struct iommufd_viommu, obj);
+}
+
int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd);
void iommufd_viommu_destroy(struct iommufd_object *obj);
+int iommufd_viommu_set_vdev_id(struct iommufd_ucmd *ucmd);
+int iommufd_viommu_unset_vdev_id(struct iommufd_ucmd *ucmd);

#ifdef CONFIG_IOMMUFD_TEST
int iommufd_test(struct iommufd_ucmd *ucmd);
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 288ee51b6829..199ad90fa36b 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -334,6 +334,8 @@ union ucmd_buffer {
struct iommu_option option;
struct iommu_vfio_ioas vfio_ioas;
struct iommu_viommu_alloc viommu;
+ struct iommu_viommu_set_vdev_id set_vdev_id;
+ struct iommu_viommu_unset_vdev_id unset_vdev_id;
#ifdef CONFIG_IOMMUFD_TEST
struct iommu_test_cmd test;
#endif
@@ -387,6 +389,10 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
__reserved),
IOCTL_OP(IOMMU_VIOMMU_ALLOC, iommufd_viommu_alloc_ioctl,
struct iommu_viommu_alloc, out_viommu_id),
+ IOCTL_OP(IOMMU_VIOMMU_SET_VDEV_ID, iommufd_viommu_set_vdev_id,
+ struct iommu_viommu_set_vdev_id, vdev_id),
+ IOCTL_OP(IOMMU_VIOMMU_UNSET_VDEV_ID, iommufd_viommu_unset_vdev_id,
+ struct iommu_viommu_unset_vdev_id, vdev_id),
#ifdef CONFIG_IOMMUFD_TEST
IOCTL_OP(IOMMU_TEST_CMD, iommufd_test, struct iommu_test_cmd, last),
#endif
diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
index 200653a4bf57..8ffcd72b16b8 100644
--- a/drivers/iommu/iommufd/viommu.c
+++ b/drivers/iommu/iommufd/viommu.c
@@ -8,6 +8,15 @@ void iommufd_viommu_destroy(struct iommufd_object *obj)
{
struct iommufd_viommu *viommu =
container_of(obj, struct iommufd_viommu, obj);
+ struct iommufd_vdev_id *vdev_id;
+ unsigned long index;
+
+ xa_for_each(&viommu->vdev_ids, index, vdev_id) {
+ /* Unlocked since there should be no race in a destroy() */
+ vdev_id->idev->vdev_id = NULL;
+ kfree(vdev_id);
+ }
+ xa_destroy(&viommu->vdev_ids);

refcount_dec(&viommu->hwpt->common.obj.users);
}
@@ -53,6 +62,9 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
viommu->ictx = ucmd->ictx;
viommu->hwpt = hwpt_paging;

+ xa_init(&viommu->vdev_ids);
+ init_rwsem(&viommu->vdev_ids_rwsem);
+
refcount_inc(&viommu->hwpt->common.obj.users);

cmd->out_viommu_id = viommu->obj.id;
@@ -70,3 +82,112 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
iommufd_put_object(ucmd->ictx, &idev->obj);
return rc;
}
+
+int iommufd_viommu_set_vdev_id(struct iommufd_ucmd *ucmd)
+{
+ struct iommu_viommu_set_vdev_id *cmd = ucmd->cmd;
+ struct iommufd_vdev_id *vdev_id, *curr;
+ struct iommufd_viommu *viommu;
+ struct iommufd_device *idev;
+ int rc = 0;
+
+ if (cmd->vdev_id > ULONG_MAX)
+ return -EINVAL;
+
+ viommu = iommufd_get_viommu(ucmd, cmd->viommu_id);
+ if (IS_ERR(viommu))
+ return PTR_ERR(viommu);
+
+ idev = iommufd_get_device(ucmd, cmd->dev_id);
+ if (IS_ERR(idev)) {
+ rc = PTR_ERR(idev);
+ goto out_put_viommu;
+ }
+
+ down_write(&viommu->vdev_ids_rwsem);
+ mutex_lock(&idev->igroup->lock);
+ if (idev->vdev_id) {
+ rc = -EEXIST;
+ goto out_unlock_igroup;
+ }
+
+ vdev_id = kzalloc(sizeof(*vdev_id), GFP_KERNEL);
+ if (!vdev_id) {
+ rc = -ENOMEM;
+ goto out_unlock_igroup;
+ }
+
+ vdev_id->idev = idev;
+ vdev_id->viommu = viommu;
+ vdev_id->id = cmd->vdev_id;
+
+ curr = xa_cmpxchg(&viommu->vdev_ids, cmd->vdev_id, NULL, vdev_id,
+ GFP_KERNEL);
+ if (curr) {
+ rc = xa_err(curr) ? : -EBUSY;
+ goto out_free;
+ }
+
+ idev->vdev_id = vdev_id;
+ goto out_unlock_igroup;
+
+out_free:
+ kfree(vdev_id);
+out_unlock_igroup:
+ mutex_unlock(&idev->igroup->lock);
+ up_write(&viommu->vdev_ids_rwsem);
+ iommufd_put_object(ucmd->ictx, &idev->obj);
+out_put_viommu:
+ iommufd_put_object(ucmd->ictx, &viommu->obj);
+ return rc;
+}
+
+int iommufd_viommu_unset_vdev_id(struct iommufd_ucmd *ucmd)
+{
+ struct iommu_viommu_unset_vdev_id *cmd = ucmd->cmd;
+ struct iommufd_viommu *viommu;
+ struct iommufd_vdev_id *old;
+ struct iommufd_device *idev;
+ int rc = 0;
+
+ if (cmd->vdev_id > ULONG_MAX)
+ return -EINVAL;
+
+ viommu = iommufd_get_viommu(ucmd, cmd->viommu_id);
+ if (IS_ERR(viommu))
+ return PTR_ERR(viommu);
+
+ idev = iommufd_get_device(ucmd, cmd->dev_id);
+ if (IS_ERR(idev)) {
+ rc = PTR_ERR(idev);
+ goto out_put_viommu;
+ }
+
+ down_write(&viommu->vdev_ids_rwsem);
+ mutex_lock(&idev->igroup->lock);
+ if (!idev->vdev_id) {
+ rc = -ENOENT;
+ goto out_unlock_igroup;
+ }
+ if (idev->vdev_id->id != cmd->vdev_id) {
+ rc = -EINVAL;
+ goto out_unlock_igroup;
+ }
+
+ old = xa_cmpxchg(&viommu->vdev_ids, idev->vdev_id->id,
+ idev->vdev_id, NULL, GFP_KERNEL);
+ if (xa_is_err(old)) {
+ rc = xa_err(old);
+ goto out_unlock_igroup;
+ }
+ kfree(old);
+ idev->vdev_id = NULL;
+
+out_unlock_igroup:
+ mutex_unlock(&idev->igroup->lock);
+ up_write(&viommu->vdev_ids_rwsem);
+ iommufd_put_object(ucmd->ictx, &idev->obj);
+out_put_viommu:
+ iommufd_put_object(ucmd->ictx, &viommu->obj);
+ return rc;
+}
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 51ce6a019c34..1816e89c922d 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -52,6 +52,8 @@ enum {
IOMMUFD_CMD_HWPT_INVALIDATE = 0x8d,
IOMMUFD_CMD_FAULT_QUEUE_ALLOC = 0x8e,
IOMMUFD_CMD_VIOMMU_ALLOC = 0x8f,
+ IOMMUFD_CMD_VIOMMU_SET_VDEV_ID = 0x90,
+ IOMMUFD_CMD_VIOMMU_UNSET_VDEV_ID = 0x91,
};

/**
@@ -882,4 +884,42 @@ struct iommu_viommu_alloc {
__u32 out_viommu_id;
};
#define IOMMU_VIOMMU_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VIOMMU_ALLOC)
+
+/**
+ * struct iommu_viommu_set_vdev_id - ioctl(IOMMU_VIOMMU_SET_VDEV_ID)
+ * @size: sizeof(struct iommu_viommu_set_vdev_id)
+ * @viommu_id: viommu ID to associate with the device to store its virtual ID
+ * @dev_id: device ID to set its virtual ID
+ * @__reserved: Must be 0
+ * @vdev_id: Virtual device ID
+ *
+ * Set a viommu-specific virtual ID of a device
+ */
+struct iommu_viommu_set_vdev_id {
+ __u32 size;
+ __u32 viommu_id;
+ __u32 dev_id;
+ __u32 __reserved;
+ __aligned_u64 vdev_id;
+};
+#define IOMMU_VIOMMU_SET_VDEV_ID _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VIOMMU_SET_VDEV_ID)
+
+/**
+ * struct iommu_viommu_unset_vdev_id - ioctl(IOMMU_VIOMMU_UNSET_VDEV_ID)
+ * @size: sizeof(struct iommu_viommu_unset_vdev_id)
+ * @viommu_id: viommu ID associated with the device to delete its virtual ID
+ * @dev_id: device ID to unset its virtual ID
+ * @__reserved: Must be 0
+ * @vdev_id: Virtual device ID (for verification)
+ *
+ * Unset a viommu-specific virtual ID of a device
+ */
+struct iommu_viommu_unset_vdev_id {
+ __u32 size;
+ __u32 viommu_id;
+ __u32 dev_id;
+ __u32 __reserved;
+ __aligned_u64 vdev_id;
+};
+#define IOMMU_VIOMMU_UNSET_VDEV_ID _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VIOMMU_UNSET_VDEV_ID)
#endif
--
2.43.0