[PATCH v5 17/19] vfio: Add VFIO_DEVICE_AT[DE]TACH_IOMMUFD_PT

Yi Liu
2023-02-27T11:12:28Z

This adds ioctl for userspace to attach device cdev fd to and detach
from IOAS/hw_pagetable managed by iommufd.

VFIO_DEVICE_ATTACH_IOMMUFD_PT: attach vfio device to IOAS, hw_pagetable
managed by iommufd. Attach can be
undo by VFIO_DEVICE_DETACH_IOMMUFD_PT
or device fd close.
VFIO_DEVICE_DETACH_IOMMUFD_PT: detach vfio device from the current attached
IOAS or hw_pagetable managed by iommufd.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
---
drivers/vfio/device_cdev.c | 76 ++++++++++++++++++++++++++++++++++++++
drivers/vfio/vfio.h | 16 ++++++++
drivers/vfio/vfio_main.c | 8 ++++
include/uapi/linux/vfio.h | 52 ++++++++++++++++++++++++++
4 files changed, 152 insertions(+)

diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
index 37f80e368551..5b5a249a6612 100644
--- a/drivers/vfio/device_cdev.c
+++ b/drivers/vfio/device_cdev.c
@@ -191,6 +191,82 @@ long vfio_device_ioctl_bind_iommufd(struct vfio_device_file *df,
return ret;
}

+int vfio_ioctl_device_attach(struct vfio_device_file *df,
+ void __user *arg)
+{
+ struct vfio_device *device = df->device;
+ struct vfio_device_attach_iommufd_pt attach;
+ unsigned long minsz;
+ int ret;
+
+ minsz = offsetofend(struct vfio_device_attach_iommufd_pt, pt_id);
+
+ if (copy_from_user(&attach, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (attach.argsz < minsz || attach.flags ||
+ attach.pt_id == IOMMUFD_INVALID_ID)
+ return -EINVAL;
+
+ if (!device->ops->bind_iommufd)
+ return -ENODEV;
+
+ mutex_lock(&device->dev_set->lock);
+ if (df->noiommu) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ ret = device->ops->attach_ioas(device, &attach.pt_id);
+ if (ret)
+ goto out_unlock;
+
+ ret = copy_to_user((void __user *)arg +
+ offsetofend(struct vfio_device_attach_iommufd_pt, flags),
+ &attach.pt_id,
+ sizeof(attach.pt_id)) ? -EFAULT : 0;
+ if (ret)
+ goto out_detach;
+ mutex_unlock(&device->dev_set->lock);
+
+ return 0;
+
+out_detach:
+ device->ops->detach_ioas(device);
+out_unlock:
+ mutex_unlock(&device->dev_set->lock);
+ return ret;
+}
+
+int vfio_ioctl_device_detach(struct vfio_device_file *df,
+ void __user *arg)
+{
+ struct vfio_device *device = df->device;
+ struct vfio_device_detach_iommufd_pt detach;
+ unsigned long minsz;
+
+ minsz = offsetofend(struct vfio_device_detach_iommufd_pt, flags);
+
+ if (copy_from_user(&detach, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (detach.argsz < minsz || detach.flags)
+ return -EINVAL;
+
+ if (!device->ops->bind_iommufd)
+ return -ENODEV;
+
+ mutex_lock(&device->dev_set->lock);
+ if (df->noiommu) {
+ mutex_unlock(&device->dev_set->lock);
+ return -EINVAL;
+ }
+ device->ops->detach_ioas(device);
+ mutex_unlock(&device->dev_set->lock);
+
+ return 0;
+}
+
static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
{
return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev));
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 4716a904e63b..5a1ceb014779 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -274,6 +274,10 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep);
void vfio_device_cdev_close(struct vfio_device_file *df);
long vfio_device_ioctl_bind_iommufd(struct vfio_device_file *df,
unsigned long arg);
+int vfio_ioctl_device_attach(struct vfio_device_file *df,
+ void __user *arg);
+int vfio_ioctl_device_detach(struct vfio_device_file *df,
+ void __user *arg);
int vfio_cdev_init(struct class *device_class);
void vfio_cdev_cleanup(void);
#else
@@ -307,6 +311,18 @@ static inline long vfio_device_ioctl_bind_iommufd(struct vfio_device_file *df,
return -EOPNOTSUPP;
}

+static inline int vfio_ioctl_device_attach(struct vfio_device_file *df,
+ void __user *arg)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int vfio_ioctl_device_detach(struct vfio_device_file *df,
+ void __user *arg)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int vfio_cdev_init(struct class *device_class)
{
return 0;
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 69d0add930bb..f68550fe206f 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -1161,6 +1161,14 @@ static long vfio_device_fops_unl_ioctl(struct file *filep,
ret = vfio_ioctl_device_feature(device, (void __user *)arg);
break;

+ case VFIO_DEVICE_ATTACH_IOMMUFD_PT:
+ ret = vfio_ioctl_device_attach(df, (void __user *)arg);
+ break;
+
+ case VFIO_DEVICE_DETACH_IOMMUFD_PT:
+ ret = vfio_ioctl_device_detach(df, (void __user *)arg);
+ break;
+
default:
if (unlikely(!device->ops->ioctl))
ret = -EINVAL;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 92aa8dbc970a..ff8753d0abb0 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -228,6 +228,58 @@ struct vfio_device_bind_iommufd {

#define VFIO_DEVICE_BIND_IOMMUFD _IO(VFIO_TYPE, VFIO_BASE + 19)

+/*
+ * VFIO_DEVICE_ATTACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 20,
+ * struct vfio_device_attach_iommufd_pt)
+ *
+ * Attach a vfio device to an iommufd address space specified by IOAS
+ * id or hw_pagetable (hwpt) id.
+ *
+ * Available only after a device has been bound to iommufd via
+ * VFIO_DEVICE_BIND_IOMMUFD
+ *
+ * Undo by VFIO_DEVICE_DETACH_IOMMUFD_PT or device fd close.
+ *
+ * @argsz: user filled size of this data.
+ * @flags: must be 0.
+ * @pt_id: Input the target id which can represent an ioas or a hwpt
+ * allocated via iommufd subsystem.
+ * Output the attached hwpt id which could be the specified
+ * hwpt itself or a hwpt automatically created for the
+ * specified ioas by kernel during the attachment.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+struct vfio_device_attach_iommufd_pt {
+ __u32 argsz;
+ __u32 flags;
+ __u32 pt_id;
+};
+
+#define VFIO_DEVICE_ATTACH_IOMMUFD_PT _IO(VFIO_TYPE, VFIO_BASE + 20)
+
+/*
+ * VFIO_DEVICE_DETACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 21,
+ * struct vfio_device_detach_iommufd_pt)
+ *
+ * Detach a vfio device from the iommufd address space it has been
+ * attached to. After it, device should be in a blocking DMA state.
+ *
+ * Available only after a device has been bound to iommufd via
+ * VFIO_DEVICE_BIND_IOMMUFD
+ *
+ * @argsz: user filled size of this data.
+ * @flags: must be 0.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+struct vfio_device_detach_iommufd_pt {
+ __u32 argsz;
+ __u32 flags;
+};
+
+#define VFIO_DEVICE_DETACH_IOMMUFD_PT _IO(VFIO_TYPE, VFIO_BASE + 21)
+
/**
* VFIO_DEVICE_GET_INFO - _IOR(VFIO_TYPE, VFIO_BASE + 7,
* struct vfio_device_info)
--
2.34.1