diff mbox series

[v12,18/24] vfio: Add VFIO_DEVICE_BIND_IOMMUFD

Message ID 20230602121653.80017-19-yi.l.liu@intel.com (mailing list archive)
State New, archived
Headers show
Series Add vfio_device cdev for iommufd support | expand

Commit Message

Yi Liu June 2, 2023, 12:16 p.m. UTC
This adds ioctl for userspace to bind device cdev fd to iommufd.

    VFIO_DEVICE_BIND_IOMMUFD: bind device to an iommufd, hence gain DMA
			      control provided by the iommufd. open_device
			      op is called after bind_iommufd op.

Tested-by: Yanting Jiang <yanting.jiang@intel.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Tested-by: Terrence Xu <terrence.xu@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 drivers/vfio/device_cdev.c | 123 +++++++++++++++++++++++++++++++++++++
 drivers/vfio/vfio.h        |  13 ++++
 drivers/vfio/vfio_main.c   |   5 ++
 include/linux/vfio.h       |   3 +-
 include/uapi/linux/vfio.h  |  27 ++++++++
 5 files changed, 170 insertions(+), 1 deletion(-)

Comments

Alex Williamson June 12, 2023, 10:27 p.m. UTC | #1
On Fri,  2 Jun 2023 05:16:47 -0700
Yi Liu <yi.l.liu@intel.com> wrote:

> This adds ioctl for userspace to bind device cdev fd to iommufd.
> 
>     VFIO_DEVICE_BIND_IOMMUFD: bind device to an iommufd, hence gain DMA
> 			      control provided by the iommufd. open_device
> 			      op is called after bind_iommufd op.
> 
> Tested-by: Yanting Jiang <yanting.jiang@intel.com>
> Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> Tested-by: Terrence Xu <terrence.xu@intel.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>  drivers/vfio/device_cdev.c | 123 +++++++++++++++++++++++++++++++++++++
>  drivers/vfio/vfio.h        |  13 ++++
>  drivers/vfio/vfio_main.c   |   5 ++
>  include/linux/vfio.h       |   3 +-
>  include/uapi/linux/vfio.h  |  27 ++++++++
>  5 files changed, 170 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
> index 1c640016a824..a4498ddbe774 100644
> --- a/drivers/vfio/device_cdev.c
> +++ b/drivers/vfio/device_cdev.c
> @@ -3,6 +3,7 @@
>   * Copyright (c) 2023 Intel Corporation.
>   */
>  #include <linux/vfio.h>
> +#include <linux/iommufd.h>
>  
>  #include "vfio.h"
>  
> @@ -44,6 +45,128 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep)
>  	return ret;
>  }
>  
> +static void vfio_device_get_kvm_safe(struct vfio_device_file *df)
> +{
> +	spin_lock(&df->kvm_ref_lock);
> +	if (df->kvm)
> +		_vfio_device_get_kvm_safe(df->device, df->kvm);
> +	spin_unlock(&df->kvm_ref_lock);
> +}
> +
> +void vfio_df_cdev_close(struct vfio_device_file *df)
> +{
> +	struct vfio_device *device = df->device;
> +
> +	/*
> +	 * In the time of close, there is no contention with another one
> +	 * changing this flag.  So read df->access_granted without lock
> +	 * and no smp_load_acquire() is ok.
> +	 */
> +	if (!df->access_granted)
> +		return;
> +
> +	mutex_lock(&device->dev_set->lock);
> +	vfio_df_close(df);
> +	vfio_device_put_kvm(device);
> +	iommufd_ctx_put(df->iommufd);
> +	device->cdev_opened = false;
> +	mutex_unlock(&device->dev_set->lock);
> +	vfio_device_unblock_group(device);
> +}
> +
> +static struct iommufd_ctx *vfio_get_iommufd_from_fd(int fd)
> +{
> +	struct iommufd_ctx *iommufd;
> +	struct fd f;
> +
> +	f = fdget(fd);
> +	if (!f.file)
> +		return ERR_PTR(-EBADF);
> +
> +	iommufd = iommufd_ctx_from_file(f.file);
> +
> +	fdput(f);
> +	return iommufd;
> +}
> +
> +long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> +				struct vfio_device_bind_iommufd __user *arg)
> +{
> +	struct vfio_device *device = df->device;
> +	struct vfio_device_bind_iommufd bind;
> +	unsigned long minsz;
> +	int ret;
> +
> +	static_assert(__same_type(arg->out_devid, df->devid));
> +
> +	minsz = offsetofend(struct vfio_device_bind_iommufd, out_devid);
> +
> +	if (copy_from_user(&bind, arg, minsz))
> +		return -EFAULT;
> +
> +	if (bind.argsz < minsz || bind.flags || bind.iommufd < 0)
> +		return -EINVAL;
> +
> +	/* BIND_IOMMUFD only allowed for cdev fds */
> +	if (df->group)
> +		return -EINVAL;
> +
> +	ret = vfio_device_block_group(device);
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&device->dev_set->lock);
> +	/* one device cannot be bound twice */
> +	if (df->access_granted) {
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +
> +	df->iommufd = vfio_get_iommufd_from_fd(bind.iommufd);
> +	if (IS_ERR(df->iommufd)) {
> +		ret = PTR_ERR(df->iommufd);
> +		df->iommufd = NULL;
> +		goto out_unlock;
> +	}
> +
> +	/*
> +	 * Before the device open, get the KVM pointer currently
> +	 * associated with the device file (if there is) and obtain
> +	 * a reference.  This reference is held until device closed.
> +	 * Save the pointer in the device for use by drivers.
> +	 */
> +	vfio_device_get_kvm_safe(df);
> +
> +	ret = vfio_df_open(df);
> +	if (ret)
> +		goto out_put_kvm;
> +
> +	ret = copy_to_user(&arg->out_devid, &df->devid,
> +			   sizeof(df->devid)) ? -EFAULT : 0;
> +	if (ret)
> +		goto out_close_device;
> +
> +	/*
> +	 * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
> +	 * read/write/mmap
> +	 */
> +	smp_store_release(&df->access_granted, true);
> +	device->cdev_opened = true;
> +	mutex_unlock(&device->dev_set->lock);
> +	return 0;
> +
> +out_close_device:
> +	vfio_df_close(df);
> +out_put_kvm:
> +	vfio_device_put_kvm(device);
> +	iommufd_ctx_put(df->iommufd);
> +	df->iommufd = NULL;
> +out_unlock:
> +	mutex_unlock(&device->dev_set->lock);
> +	vfio_device_unblock_group(device);
> +	return ret;
> +}
> +
>  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 d12b5b524bfc..42de40d2cd4d 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -287,6 +287,9 @@ static inline void vfio_device_del(struct vfio_device *device)
>  }
>  
>  int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep);
> +void vfio_df_cdev_close(struct vfio_device_file *df);
> +long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> +				struct vfio_device_bind_iommufd __user *arg);
>  int vfio_cdev_init(struct class *device_class);
>  void vfio_cdev_cleanup(void);
>  #else
> @@ -310,6 +313,16 @@ static inline int vfio_device_fops_cdev_open(struct inode *inode,
>  	return 0;
>  }
>  
> +static inline void vfio_df_cdev_close(struct vfio_device_file *df)
> +{
> +}
> +
> +static inline long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> +					      struct vfio_device_bind_iommufd __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 ef55af75f459..9ba4d420eda2 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -572,6 +572,8 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep)
>  
>  	if (df->group)
>  		vfio_df_group_close(df);
> +	else
> +		vfio_df_cdev_close(df);
>  
>  	vfio_device_put_registration(device);
>  
> @@ -1145,6 +1147,9 @@ static long vfio_device_fops_unl_ioctl(struct file *filep,
>  	struct vfio_device *device = df->device;
>  	int ret;
>  
> +	if (cmd == VFIO_DEVICE_BIND_IOMMUFD)
> +		return vfio_df_ioctl_bind_iommufd(df, (void __user *)arg);
> +
>  	/* Paired with smp_store_release() following vfio_df_open() */
>  	if (!smp_load_acquire(&df->access_granted))
>  		return -EINVAL;
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 83cc5dc28b7a..e80a8ac86e46 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -66,6 +66,7 @@ struct vfio_device {
>  	struct iommufd_device *iommufd_device;
>  	bool iommufd_attached;
>  #endif
> +	bool cdev_opened:1;

Perhaps a more strongly defined data type here as well and roll
iommufd_attached into the same bit field scheme.

>  };
>  
>  /**
> @@ -170,7 +171,7 @@ vfio_iommufd_device_hot_reset_devid(struct vfio_device *vdev,
>  
>  static inline bool vfio_device_cdev_opened(struct vfio_device *device)
>  {
> -	return false;
> +	return device->cdev_opened;
>  }
>  
>  /**
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index f753124e1c82..7296012b7f36 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -194,6 +194,33 @@ struct vfio_group_status {
>  
>  /* --------------- IOCTLs for DEVICE file descriptors --------------- */
>  
> +/*
> + * VFIO_DEVICE_BIND_IOMMUFD - _IOR(VFIO_TYPE, VFIO_BASE + 18,
> + *				   struct vfio_device_bind_iommufd)
> + * @argsz:	 User filled size of this data.
> + * @flags:	 Must be 0.
> + * @iommufd:	 iommufd to bind.
> + * @out_devid:	 The device id generated by this bind. devid is a handle for
> + *		 this device/iommufd bond and can be used in IOMMUFD commands.
> + *
> + * Bind a vfio_device to the specified iommufd.
> + *
> + * User is restricted from accessing the device before the binding operation
> + * is completed.
> + *
> + * Unbind is automatically conducted when device fd is closed.
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +struct vfio_device_bind_iommufd {
> +	__u32		argsz;
> +	__u32		flags;
> +	__s32		iommufd;
> +	__u32		out_devid;
> +};
> +
> +#define VFIO_DEVICE_BIND_IOMMUFD	_IO(VFIO_TYPE, VFIO_BASE + 18)
> +

Why are we still defining device ioctls 18-20 before existing device
ioctls?  18 should be defined after 17...  Thanks,

Alex

>  /**
>   * VFIO_DEVICE_GET_INFO - _IOR(VFIO_TYPE, VFIO_BASE + 7,
>   *						struct vfio_device_info)
Yi Liu June 13, 2023, 5:48 a.m. UTC | #2
> From: Alex Williamson <alex.williamson@redhat.com>
> Sent: Tuesday, June 13, 2023 6:27 AM
> 
> On Fri,  2 Jun 2023 05:16:47 -0700
> Yi Liu <yi.l.liu@intel.com> wrote:
> 
> > This adds ioctl for userspace to bind device cdev fd to iommufd.
> >
> >     VFIO_DEVICE_BIND_IOMMUFD: bind device to an iommufd, hence gain DMA
> > 			      control provided by the iommufd. open_device
> > 			      op is called after bind_iommufd op.
> >
> > Tested-by: Yanting Jiang <yanting.jiang@intel.com>
> > Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> > Tested-by: Terrence Xu <terrence.xu@intel.com>
> > Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> > ---
> >  drivers/vfio/device_cdev.c | 123 +++++++++++++++++++++++++++++++++++++
> >  drivers/vfio/vfio.h        |  13 ++++
> >  drivers/vfio/vfio_main.c   |   5 ++
> >  include/linux/vfio.h       |   3 +-
> >  include/uapi/linux/vfio.h  |  27 ++++++++
> >  5 files changed, 170 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
> > index 1c640016a824..a4498ddbe774 100644
> > --- a/drivers/vfio/device_cdev.c
> > +++ b/drivers/vfio/device_cdev.c
> > @@ -3,6 +3,7 @@
> >   * Copyright (c) 2023 Intel Corporation.
> >   */
> >  #include <linux/vfio.h>
> > +#include <linux/iommufd.h>
> >
> >  #include "vfio.h"
> >
> > @@ -44,6 +45,128 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct
> file *filep)
> >  	return ret;
> >  }
> >
> > +static void vfio_device_get_kvm_safe(struct vfio_device_file *df)
> > +{
> > +	spin_lock(&df->kvm_ref_lock);
> > +	if (df->kvm)
> > +		_vfio_device_get_kvm_safe(df->device, df->kvm);
> > +	spin_unlock(&df->kvm_ref_lock);
> > +}
> > +
> > +void vfio_df_cdev_close(struct vfio_device_file *df)
> > +{
> > +	struct vfio_device *device = df->device;
> > +
> > +	/*
> > +	 * In the time of close, there is no contention with another one
> > +	 * changing this flag.  So read df->access_granted without lock
> > +	 * and no smp_load_acquire() is ok.
> > +	 */
> > +	if (!df->access_granted)
> > +		return;
> > +
> > +	mutex_lock(&device->dev_set->lock);
> > +	vfio_df_close(df);
> > +	vfio_device_put_kvm(device);
> > +	iommufd_ctx_put(df->iommufd);
> > +	device->cdev_opened = false;
> > +	mutex_unlock(&device->dev_set->lock);
> > +	vfio_device_unblock_group(device);
> > +}
> > +
> > +static struct iommufd_ctx *vfio_get_iommufd_from_fd(int fd)
> > +{
> > +	struct iommufd_ctx *iommufd;
> > +	struct fd f;
> > +
> > +	f = fdget(fd);
> > +	if (!f.file)
> > +		return ERR_PTR(-EBADF);
> > +
> > +	iommufd = iommufd_ctx_from_file(f.file);
> > +
> > +	fdput(f);
> > +	return iommufd;
> > +}
> > +
> > +long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> > +				struct vfio_device_bind_iommufd __user *arg)
> > +{
> > +	struct vfio_device *device = df->device;
> > +	struct vfio_device_bind_iommufd bind;
> > +	unsigned long minsz;
> > +	int ret;
> > +
> > +	static_assert(__same_type(arg->out_devid, df->devid));
> > +
> > +	minsz = offsetofend(struct vfio_device_bind_iommufd, out_devid);
> > +
> > +	if (copy_from_user(&bind, arg, minsz))
> > +		return -EFAULT;
> > +
> > +	if (bind.argsz < minsz || bind.flags || bind.iommufd < 0)
> > +		return -EINVAL;
> > +
> > +	/* BIND_IOMMUFD only allowed for cdev fds */
> > +	if (df->group)
> > +		return -EINVAL;
> > +
> > +	ret = vfio_device_block_group(device);
> > +	if (ret)
> > +		return ret;
> > +
> > +	mutex_lock(&device->dev_set->lock);
> > +	/* one device cannot be bound twice */
> > +	if (df->access_granted) {
> > +		ret = -EINVAL;
> > +		goto out_unlock;
> > +	}
> > +
> > +	df->iommufd = vfio_get_iommufd_from_fd(bind.iommufd);
> > +	if (IS_ERR(df->iommufd)) {
> > +		ret = PTR_ERR(df->iommufd);
> > +		df->iommufd = NULL;
> > +		goto out_unlock;
> > +	}
> > +
> > +	/*
> > +	 * Before the device open, get the KVM pointer currently
> > +	 * associated with the device file (if there is) and obtain
> > +	 * a reference.  This reference is held until device closed.
> > +	 * Save the pointer in the device for use by drivers.
> > +	 */
> > +	vfio_device_get_kvm_safe(df);
> > +
> > +	ret = vfio_df_open(df);
> > +	if (ret)
> > +		goto out_put_kvm;
> > +
> > +	ret = copy_to_user(&arg->out_devid, &df->devid,
> > +			   sizeof(df->devid)) ? -EFAULT : 0;
> > +	if (ret)
> > +		goto out_close_device;
> > +
> > +	/*
> > +	 * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
> > +	 * read/write/mmap
> > +	 */
> > +	smp_store_release(&df->access_granted, true);
> > +	device->cdev_opened = true;
> > +	mutex_unlock(&device->dev_set->lock);
> > +	return 0;
> > +
> > +out_close_device:
> > +	vfio_df_close(df);
> > +out_put_kvm:
> > +	vfio_device_put_kvm(device);
> > +	iommufd_ctx_put(df->iommufd);
> > +	df->iommufd = NULL;
> > +out_unlock:
> > +	mutex_unlock(&device->dev_set->lock);
> > +	vfio_device_unblock_group(device);
> > +	return ret;
> > +}
> > +
> >  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 d12b5b524bfc..42de40d2cd4d 100644
> > --- a/drivers/vfio/vfio.h
> > +++ b/drivers/vfio/vfio.h
> > @@ -287,6 +287,9 @@ static inline void vfio_device_del(struct vfio_device *device)
> >  }
> >
> >  int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep);
> > +void vfio_df_cdev_close(struct vfio_device_file *df);
> > +long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> > +				struct vfio_device_bind_iommufd __user *arg);
> >  int vfio_cdev_init(struct class *device_class);
> >  void vfio_cdev_cleanup(void);
> >  #else
> > @@ -310,6 +313,16 @@ static inline int vfio_device_fops_cdev_open(struct inode
> *inode,
> >  	return 0;
> >  }
> >
> > +static inline void vfio_df_cdev_close(struct vfio_device_file *df)
> > +{
> > +}
> > +
> > +static inline long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> > +					      struct vfio_device_bind_iommufd __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 ef55af75f459..9ba4d420eda2 100644
> > --- a/drivers/vfio/vfio_main.c
> > +++ b/drivers/vfio/vfio_main.c
> > @@ -572,6 +572,8 @@ static int vfio_device_fops_release(struct inode *inode, struct
> file *filep)
> >
> >  	if (df->group)
> >  		vfio_df_group_close(df);
> > +	else
> > +		vfio_df_cdev_close(df);
> >
> >  	vfio_device_put_registration(device);
> >
> > @@ -1145,6 +1147,9 @@ static long vfio_device_fops_unl_ioctl(struct file *filep,
> >  	struct vfio_device *device = df->device;
> >  	int ret;
> >
> > +	if (cmd == VFIO_DEVICE_BIND_IOMMUFD)
> > +		return vfio_df_ioctl_bind_iommufd(df, (void __user *)arg);
> > +
> >  	/* Paired with smp_store_release() following vfio_df_open() */
> >  	if (!smp_load_acquire(&df->access_granted))
> >  		return -EINVAL;
> > diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> > index 83cc5dc28b7a..e80a8ac86e46 100644
> > --- a/include/linux/vfio.h
> > +++ b/include/linux/vfio.h
> > @@ -66,6 +66,7 @@ struct vfio_device {
> >  	struct iommufd_device *iommufd_device;
> >  	bool iommufd_attached;
> >  #endif
> > +	bool cdev_opened:1;
> 
> Perhaps a more strongly defined data type here as well and roll
> iommufd_attached into the same bit field scheme.

Ok, then needs to make iommufd_attached always defined.

> 
> >  };
> >
> >  /**
> > @@ -170,7 +171,7 @@ vfio_iommufd_device_hot_reset_devid(struct vfio_device
> *vdev,
> >
> >  static inline bool vfio_device_cdev_opened(struct vfio_device *device)
> >  {
> > -	return false;
> > +	return device->cdev_opened;
> >  }
> >
> >  /**
> > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> > index f753124e1c82..7296012b7f36 100644
> > --- a/include/uapi/linux/vfio.h
> > +++ b/include/uapi/linux/vfio.h
> > @@ -194,6 +194,33 @@ struct vfio_group_status {
> >
> >  /* --------------- IOCTLs for DEVICE file descriptors --------------- */
> >
> > +/*
> > + * VFIO_DEVICE_BIND_IOMMUFD - _IOR(VFIO_TYPE, VFIO_BASE + 18,
> > + *				   struct vfio_device_bind_iommufd)
> > + * @argsz:	 User filled size of this data.
> > + * @flags:	 Must be 0.
> > + * @iommufd:	 iommufd to bind.
> > + * @out_devid:	 The device id generated by this bind. devid is a handle for
> > + *		 this device/iommufd bond and can be used in IOMMUFD commands.
> > + *
> > + * Bind a vfio_device to the specified iommufd.
> > + *
> > + * User is restricted from accessing the device before the binding operation
> > + * is completed.
> > + *
> > + * Unbind is automatically conducted when device fd is closed.
> > + *
> > + * Return: 0 on success, -errno on failure.
> > + */
> > +struct vfio_device_bind_iommufd {
> > +	__u32		argsz;
> > +	__u32		flags;
> > +	__s32		iommufd;
> > +	__u32		out_devid;
> > +};
> > +
> > +#define VFIO_DEVICE_BIND_IOMMUFD	_IO(VFIO_TYPE, VFIO_BASE + 18)
> > +
> 
> Why are we still defining device ioctls 18-20 before existing device
> ioctls?  18 should be defined after 17...  Thanks,

Yes. I put it here as it is supposed to be the first doable ioctl for cdev fds.
But you are right, it should be ordered by offset.

Regards,
Yi Liu

> Alex
> 
> >  /**
> >   * VFIO_DEVICE_GET_INFO - _IOR(VFIO_TYPE, VFIO_BASE + 7,
> >   *						struct vfio_device_info)
Alex Williamson June 13, 2023, 2:18 p.m. UTC | #3
On Tue, 13 Jun 2023 05:48:46 +0000
"Liu, Yi L" <yi.l.liu@intel.com> wrote:

> > From: Alex Williamson <alex.williamson@redhat.com>
> > Sent: Tuesday, June 13, 2023 6:27 AM
> > 
> > On Fri,  2 Jun 2023 05:16:47 -0700
> > Yi Liu <yi.l.liu@intel.com> wrote:
> >   
> > > This adds ioctl for userspace to bind device cdev fd to iommufd.
> > >
> > >     VFIO_DEVICE_BIND_IOMMUFD: bind device to an iommufd, hence gain DMA
> > > 			      control provided by the iommufd. open_device
> > > 			      op is called after bind_iommufd op.
> > >
> > > Tested-by: Yanting Jiang <yanting.jiang@intel.com>
> > > Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> > > Tested-by: Terrence Xu <terrence.xu@intel.com>
> > > Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> > > ---
> > >  drivers/vfio/device_cdev.c | 123 +++++++++++++++++++++++++++++++++++++
> > >  drivers/vfio/vfio.h        |  13 ++++
> > >  drivers/vfio/vfio_main.c   |   5 ++
> > >  include/linux/vfio.h       |   3 +-
> > >  include/uapi/linux/vfio.h  |  27 ++++++++
> > >  5 files changed, 170 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
> > > index 1c640016a824..a4498ddbe774 100644
> > > --- a/drivers/vfio/device_cdev.c
> > > +++ b/drivers/vfio/device_cdev.c
> > > @@ -3,6 +3,7 @@
> > >   * Copyright (c) 2023 Intel Corporation.
> > >   */
> > >  #include <linux/vfio.h>
> > > +#include <linux/iommufd.h>
> > >
> > >  #include "vfio.h"
> > >
> > > @@ -44,6 +45,128 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct  
> > file *filep)  
> > >  	return ret;
> > >  }
> > >
> > > +static void vfio_device_get_kvm_safe(struct vfio_device_file *df)
> > > +{
> > > +	spin_lock(&df->kvm_ref_lock);
> > > +	if (df->kvm)
> > > +		_vfio_device_get_kvm_safe(df->device, df->kvm);
> > > +	spin_unlock(&df->kvm_ref_lock);
> > > +}
> > > +
> > > +void vfio_df_cdev_close(struct vfio_device_file *df)
> > > +{
> > > +	struct vfio_device *device = df->device;
> > > +
> > > +	/*
> > > +	 * In the time of close, there is no contention with another one
> > > +	 * changing this flag.  So read df->access_granted without lock
> > > +	 * and no smp_load_acquire() is ok.
> > > +	 */
> > > +	if (!df->access_granted)
> > > +		return;
> > > +
> > > +	mutex_lock(&device->dev_set->lock);
> > > +	vfio_df_close(df);
> > > +	vfio_device_put_kvm(device);
> > > +	iommufd_ctx_put(df->iommufd);
> > > +	device->cdev_opened = false;
> > > +	mutex_unlock(&device->dev_set->lock);
> > > +	vfio_device_unblock_group(device);
> > > +}
> > > +
> > > +static struct iommufd_ctx *vfio_get_iommufd_from_fd(int fd)
> > > +{
> > > +	struct iommufd_ctx *iommufd;
> > > +	struct fd f;
> > > +
> > > +	f = fdget(fd);
> > > +	if (!f.file)
> > > +		return ERR_PTR(-EBADF);
> > > +
> > > +	iommufd = iommufd_ctx_from_file(f.file);
> > > +
> > > +	fdput(f);
> > > +	return iommufd;
> > > +}
> > > +
> > > +long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> > > +				struct vfio_device_bind_iommufd __user *arg)
> > > +{
> > > +	struct vfio_device *device = df->device;
> > > +	struct vfio_device_bind_iommufd bind;
> > > +	unsigned long minsz;
> > > +	int ret;
> > > +
> > > +	static_assert(__same_type(arg->out_devid, df->devid));
> > > +
> > > +	minsz = offsetofend(struct vfio_device_bind_iommufd, out_devid);
> > > +
> > > +	if (copy_from_user(&bind, arg, minsz))
> > > +		return -EFAULT;
> > > +
> > > +	if (bind.argsz < minsz || bind.flags || bind.iommufd < 0)
> > > +		return -EINVAL;
> > > +
> > > +	/* BIND_IOMMUFD only allowed for cdev fds */
> > > +	if (df->group)
> > > +		return -EINVAL;
> > > +
> > > +	ret = vfio_device_block_group(device);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	mutex_lock(&device->dev_set->lock);
> > > +	/* one device cannot be bound twice */
> > > +	if (df->access_granted) {
> > > +		ret = -EINVAL;
> > > +		goto out_unlock;
> > > +	}
> > > +
> > > +	df->iommufd = vfio_get_iommufd_from_fd(bind.iommufd);
> > > +	if (IS_ERR(df->iommufd)) {
> > > +		ret = PTR_ERR(df->iommufd);
> > > +		df->iommufd = NULL;
> > > +		goto out_unlock;
> > > +	}
> > > +
> > > +	/*
> > > +	 * Before the device open, get the KVM pointer currently
> > > +	 * associated with the device file (if there is) and obtain
> > > +	 * a reference.  This reference is held until device closed.
> > > +	 * Save the pointer in the device for use by drivers.
> > > +	 */
> > > +	vfio_device_get_kvm_safe(df);
> > > +
> > > +	ret = vfio_df_open(df);
> > > +	if (ret)
> > > +		goto out_put_kvm;
> > > +
> > > +	ret = copy_to_user(&arg->out_devid, &df->devid,
> > > +			   sizeof(df->devid)) ? -EFAULT : 0;
> > > +	if (ret)
> > > +		goto out_close_device;
> > > +
> > > +	/*
> > > +	 * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
> > > +	 * read/write/mmap
> > > +	 */
> > > +	smp_store_release(&df->access_granted, true);
> > > +	device->cdev_opened = true;
> > > +	mutex_unlock(&device->dev_set->lock);
> > > +	return 0;
> > > +
> > > +out_close_device:
> > > +	vfio_df_close(df);
> > > +out_put_kvm:
> > > +	vfio_device_put_kvm(device);
> > > +	iommufd_ctx_put(df->iommufd);
> > > +	df->iommufd = NULL;
> > > +out_unlock:
> > > +	mutex_unlock(&device->dev_set->lock);
> > > +	vfio_device_unblock_group(device);
> > > +	return ret;
> > > +}
> > > +
> > >  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 d12b5b524bfc..42de40d2cd4d 100644
> > > --- a/drivers/vfio/vfio.h
> > > +++ b/drivers/vfio/vfio.h
> > > @@ -287,6 +287,9 @@ static inline void vfio_device_del(struct vfio_device *device)
> > >  }
> > >
> > >  int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep);
> > > +void vfio_df_cdev_close(struct vfio_device_file *df);
> > > +long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> > > +				struct vfio_device_bind_iommufd __user *arg);
> > >  int vfio_cdev_init(struct class *device_class);
> > >  void vfio_cdev_cleanup(void);
> > >  #else
> > > @@ -310,6 +313,16 @@ static inline int vfio_device_fops_cdev_open(struct inode  
> > *inode,  
> > >  	return 0;
> > >  }
> > >
> > > +static inline void vfio_df_cdev_close(struct vfio_device_file *df)
> > > +{
> > > +}
> > > +
> > > +static inline long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> > > +					      struct vfio_device_bind_iommufd __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 ef55af75f459..9ba4d420eda2 100644
> > > --- a/drivers/vfio/vfio_main.c
> > > +++ b/drivers/vfio/vfio_main.c
> > > @@ -572,6 +572,8 @@ static int vfio_device_fops_release(struct inode *inode, struct  
> > file *filep)  
> > >
> > >  	if (df->group)
> > >  		vfio_df_group_close(df);
> > > +	else
> > > +		vfio_df_cdev_close(df);
> > >
> > >  	vfio_device_put_registration(device);
> > >
> > > @@ -1145,6 +1147,9 @@ static long vfio_device_fops_unl_ioctl(struct file *filep,
> > >  	struct vfio_device *device = df->device;
> > >  	int ret;
> > >
> > > +	if (cmd == VFIO_DEVICE_BIND_IOMMUFD)
> > > +		return vfio_df_ioctl_bind_iommufd(df, (void __user *)arg);
> > > +
> > >  	/* Paired with smp_store_release() following vfio_df_open() */
> > >  	if (!smp_load_acquire(&df->access_granted))
> > >  		return -EINVAL;
> > > diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> > > index 83cc5dc28b7a..e80a8ac86e46 100644
> > > --- a/include/linux/vfio.h
> > > +++ b/include/linux/vfio.h
> > > @@ -66,6 +66,7 @@ struct vfio_device {
> > >  	struct iommufd_device *iommufd_device;
> > >  	bool iommufd_attached;
> > >  #endif
> > > +	bool cdev_opened:1;  
> > 
> > Perhaps a more strongly defined data type here as well and roll
> > iommufd_attached into the same bit field scheme.  
> 
> Ok, then needs to make iommufd_attached always defined.

That does not follow.  Thanks,

Alex
Yi Liu June 13, 2023, 2:28 p.m. UTC | #4
> From: Alex Williamson <alex.williamson@redhat.com>
> Sent: Tuesday, June 13, 2023 10:18 PM

> > > > diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> > > > index 83cc5dc28b7a..e80a8ac86e46 100644
> > > > --- a/include/linux/vfio.h
> > > > +++ b/include/linux/vfio.h
> > > > @@ -66,6 +66,7 @@ struct vfio_device {
> > > >  	struct iommufd_device *iommufd_device;
> > > >  	bool iommufd_attached;
> > > >  #endif
> > > > +	bool cdev_opened:1;
> > >
> > > Perhaps a more strongly defined data type here as well and roll
> > > iommufd_attached into the same bit field scheme.
> >
> > Ok, then needs to make iommufd_attached always defined.
> 
> That does not follow.  Thanks,

Well, I meant the iommufd_attached now is defined only when
CONFIG_IOMMUFD is enabled. To toll it with cdev_opened, needs
to change this.

Regards,
Yi Liu
Alex Williamson June 13, 2023, 2:39 p.m. UTC | #5
On Tue, 13 Jun 2023 14:28:43 +0000
"Liu, Yi L" <yi.l.liu@intel.com> wrote:

> > From: Alex Williamson <alex.williamson@redhat.com>
> > Sent: Tuesday, June 13, 2023 10:18 PM  
> 
> > > > > diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> > > > > index 83cc5dc28b7a..e80a8ac86e46 100644
> > > > > --- a/include/linux/vfio.h
> > > > > +++ b/include/linux/vfio.h
> > > > > @@ -66,6 +66,7 @@ struct vfio_device {
> > > > >  	struct iommufd_device *iommufd_device;
> > > > >  	bool iommufd_attached;
> > > > >  #endif
> > > > > +	bool cdev_opened:1;  
> > > >
> > > > Perhaps a more strongly defined data type here as well and roll
> > > > iommufd_attached into the same bit field scheme.  
> > >
> > > Ok, then needs to make iommufd_attached always defined.  
> > 
> > That does not follow.  Thanks,  
> 
> Well, I meant the iommufd_attached now is defined only when
> CONFIG_IOMMUFD is enabled. To toll it with cdev_opened, needs
> to change this.

Understood, but I don't think it's true.  If defined we use one more
bit of the bit field, which is a consideration when we approach filling
it, but we're not using bit-shift operations to address these bits, so
why does it matter if one has compiler conditional usage?  Thanks,

Alex
Yi Liu June 13, 2023, 2:42 p.m. UTC | #6
> From: Alex Williamson <alex.williamson@redhat.com>
> Sent: Tuesday, June 13, 2023 10:40 PM
> 
> On Tue, 13 Jun 2023 14:28:43 +0000
> "Liu, Yi L" <yi.l.liu@intel.com> wrote:
> 
> > > From: Alex Williamson <alex.williamson@redhat.com>
> > > Sent: Tuesday, June 13, 2023 10:18 PM
> >
> > > > > > diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> > > > > > index 83cc5dc28b7a..e80a8ac86e46 100644
> > > > > > --- a/include/linux/vfio.h
> > > > > > +++ b/include/linux/vfio.h
> > > > > > @@ -66,6 +66,7 @@ struct vfio_device {
> > > > > >  	struct iommufd_device *iommufd_device;
> > > > > >  	bool iommufd_attached;
> > > > > >  #endif
> > > > > > +	bool cdev_opened:1;
> > > > >
> > > > > Perhaps a more strongly defined data type here as well and roll
> > > > > iommufd_attached into the same bit field scheme.
> > > >
> > > > Ok, then needs to make iommufd_attached always defined.
> > >
> > > That does not follow.  Thanks,
> >
> > Well, I meant the iommufd_attached now is defined only when
> > CONFIG_IOMMUFD is enabled. To toll it with cdev_opened, needs
> > to change this.
> 
> Understood, but I don't think it's true.  If defined we use one more
> bit of the bit field, which is a consideration when we approach filling
> it, but we're not using bit-shift operations to address these bits, so
> why does it matter if one has compiler conditional usage?  Thanks,

Aha, I see. So you are suggesting something like the below. Is it?

#if IS_ENABLED(CONFIG_IOMMUFD)
	struct iommufd_device *iommufd_device;
	u8 iommufd_attached:1;
#endif
	u8 cdev_opened:1;

Regards,
Yi Liu
Alex Williamson June 13, 2023, 2:59 p.m. UTC | #7
On Tue, 13 Jun 2023 14:42:46 +0000
"Liu, Yi L" <yi.l.liu@intel.com> wrote:

> > From: Alex Williamson <alex.williamson@redhat.com>
> > Sent: Tuesday, June 13, 2023 10:40 PM
> > 
> > On Tue, 13 Jun 2023 14:28:43 +0000
> > "Liu, Yi L" <yi.l.liu@intel.com> wrote:
> >   
> > > > From: Alex Williamson <alex.williamson@redhat.com>
> > > > Sent: Tuesday, June 13, 2023 10:18 PM  
> > >  
> > > > > > > diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> > > > > > > index 83cc5dc28b7a..e80a8ac86e46 100644
> > > > > > > --- a/include/linux/vfio.h
> > > > > > > +++ b/include/linux/vfio.h
> > > > > > > @@ -66,6 +66,7 @@ struct vfio_device {
> > > > > > >  	struct iommufd_device *iommufd_device;
> > > > > > >  	bool iommufd_attached;
> > > > > > >  #endif
> > > > > > > +	bool cdev_opened:1;  
> > > > > >
> > > > > > Perhaps a more strongly defined data type here as well and roll
> > > > > > iommufd_attached into the same bit field scheme.  
> > > > >
> > > > > Ok, then needs to make iommufd_attached always defined.  
> > > >
> > > > That does not follow.  Thanks,  
> > >
> > > Well, I meant the iommufd_attached now is defined only when
> > > CONFIG_IOMMUFD is enabled. To toll it with cdev_opened, needs
> > > to change this.  
> > 
> > Understood, but I don't think it's true.  If defined we use one more
> > bit of the bit field, which is a consideration when we approach filling
> > it, but we're not using bit-shift operations to address these bits, so
> > why does it matter if one has compiler conditional usage?  Thanks,  
> 
> Aha, I see. So you are suggesting something like the below. Is it?
> 
> #if IS_ENABLED(CONFIG_IOMMUFD)
> 	struct iommufd_device *iommufd_device;
> 	u8 iommufd_attached:1;
> #endif
> 	u8 cdev_opened:1;


Precisely.  Thanks,

Alex
Jason Gunthorpe June 23, 2023, 4:15 p.m. UTC | #8
On Fri, Jun 02, 2023 at 05:16:47AM -0700, Yi Liu wrote:
> This adds ioctl for userspace to bind device cdev fd to iommufd.
> 
>     VFIO_DEVICE_BIND_IOMMUFD: bind device to an iommufd, hence gain DMA
> 			      control provided by the iommufd. open_device
> 			      op is called after bind_iommufd op.
> 
> Tested-by: Yanting Jiang <yanting.jiang@intel.com>
> Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> Tested-by: Terrence Xu <terrence.xu@intel.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>  drivers/vfio/device_cdev.c | 123 +++++++++++++++++++++++++++++++++++++
>  drivers/vfio/vfio.h        |  13 ++++
>  drivers/vfio/vfio_main.c   |   5 ++
>  include/linux/vfio.h       |   3 +-
>  include/uapi/linux/vfio.h  |  27 ++++++++
>  5 files changed, 170 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
> index 1c640016a824..a4498ddbe774 100644
> --- a/drivers/vfio/device_cdev.c
> +++ b/drivers/vfio/device_cdev.c
> @@ -3,6 +3,7 @@
>   * Copyright (c) 2023 Intel Corporation.
>   */
>  #include <linux/vfio.h>
> +#include <linux/iommufd.h>
>  
>  #include "vfio.h"
>  
> @@ -44,6 +45,128 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep)
>  	return ret;
>  }
>  
> +static void vfio_device_get_kvm_safe(struct vfio_device_file *df)
> +{
> +	spin_lock(&df->kvm_ref_lock);
> +	if (df->kvm)
> +		_vfio_device_get_kvm_safe(df->device, df->kvm);
> +	spin_unlock(&df->kvm_ref_lock);
> +}

I'm surprised symbol_get() can be called from a spinlock, but it sure
looks like it can..

Also moving the if kvm is null test into _vfio_device_get_kvm_safe()
will save a few lines.

Also shouldn't be called _vfio_device...

> +void vfio_df_cdev_close(struct vfio_device_file *df)
> +{
> +	struct vfio_device *device = df->device;
> +
> +	/*
> +	 * In the time of close, there is no contention with another one
> +	 * changing this flag.  So read df->access_granted without lock
> +	 * and no smp_load_acquire() is ok.
> +	 */
> +	if (!df->access_granted)
> +		return;
> +
> +	mutex_lock(&device->dev_set->lock);
> +	vfio_df_close(df);
> +	vfio_device_put_kvm(device);
> +	iommufd_ctx_put(df->iommufd);
> +	device->cdev_opened = false;
> +	mutex_unlock(&device->dev_set->lock);
> +	vfio_device_unblock_group(device);
> +}

Lets call this vfio_df_unbind_iommufd() and put it near
vfio_df_ioctl_bind_iommufd()

> static struct iommufd_ctx *vfio_get_iommufd_from_fd(int fd)

This can probably be an iommufd function:
  iommufd_ctx_from_fd(int fd)

> +long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> +				struct vfio_device_bind_iommufd __user *arg)
> +{
> +	ret = copy_to_user(&arg->out_devid, &df->devid,
> +			   sizeof(df->devid)) ? -EFAULT : 0;
> +	if (ret)
> +		goto out_close_device;
> +
> +	/*
> +	 * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
> +	 * read/write/mmap
> +	 */
> +	smp_store_release(&df->access_granted, true);
> +	device->cdev_opened = true;

Move the cdev_opened up above the release just for consistency.

Jason
Yi Liu June 26, 2023, 8:34 a.m. UTC | #9
> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Saturday, June 24, 2023 12:15 AM

> >  }
> >
> > +static void vfio_device_get_kvm_safe(struct vfio_device_file *df)
> > +{
> > +	spin_lock(&df->kvm_ref_lock);
> > +	if (df->kvm)
> > +		_vfio_device_get_kvm_safe(df->device, df->kvm);
> > +	spin_unlock(&df->kvm_ref_lock);
> > +}
> 
> I'm surprised symbol_get() can be called from a spinlock, but it sure
> looks like it can..
> 
> Also moving the if kvm is null test into _vfio_device_get_kvm_safe()
> will save a few lines.
> 
> Also shouldn't be called _vfio_device...

Ah, any suggestion on the naming? How about vfio_device_get_kvm_safe_locked()?

Regards,
Yi Liu
Jason Gunthorpe June 26, 2023, 12:56 p.m. UTC | #10
On Mon, Jun 26, 2023 at 08:34:26AM +0000, Liu, Yi L wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Saturday, June 24, 2023 12:15 AM
> 
> > >  }
> > >
> > > +static void vfio_device_get_kvm_safe(struct vfio_device_file *df)
> > > +{
> > > +	spin_lock(&df->kvm_ref_lock);
> > > +	if (df->kvm)
> > > +		_vfio_device_get_kvm_safe(df->device, df->kvm);
> > > +	spin_unlock(&df->kvm_ref_lock);
> > > +}
> > 
> > I'm surprised symbol_get() can be called from a spinlock, but it sure
> > looks like it can..
> > 
> > Also moving the if kvm is null test into _vfio_device_get_kvm_safe()
> > will save a few lines.
> > 
> > Also shouldn't be called _vfio_device...
> 
> Ah, any suggestion on the naming? How about vfio_device_get_kvm_safe_locked()?

I thought you were using _df_ now for these functions?

Jason
Yi Liu June 26, 2023, 1:35 p.m. UTC | #11
> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Monday, June 26, 2023 8:56 PM
> 
> On Mon, Jun 26, 2023 at 08:34:26AM +0000, Liu, Yi L wrote:
> > > From: Jason Gunthorpe <jgg@nvidia.com>
> > > Sent: Saturday, June 24, 2023 12:15 AM
> >
> > > >  }
> > > >
> > > > +static void vfio_device_get_kvm_safe(struct vfio_device_file *df)
> > > > +{
> > > > +	spin_lock(&df->kvm_ref_lock);
> > > > +	if (df->kvm)
> > > > +		_vfio_device_get_kvm_safe(df->device, df->kvm);
> > > > +	spin_unlock(&df->kvm_ref_lock);
> > > > +}
> > >
> > > I'm surprised symbol_get() can be called from a spinlock, but it sure
> > > looks like it can..
> > >
> > > Also moving the if kvm is null test into _vfio_device_get_kvm_safe()
> > > will save a few lines.
> > >
> > > Also shouldn't be called _vfio_device...
> >
> > Ah, any suggestion on the naming? How about vfio_device_get_kvm_safe_locked()?
> 
> I thought you were using _df_ now for these functions?
> 

I see. Your point is passing df to _vfio_device_get_kvm_safe(() and
test the df->kvm within it.  Hence rename it to be _df_. I think group
path should be ok with this change as well. Let me make it.

Regards,
Yi Liu
Yi Liu June 26, 2023, 2:51 p.m. UTC | #12
> From: Liu, Yi L <yi.l.liu@intel.com>
> Sent: Monday, June 26, 2023 9:35 PM
> 
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Monday, June 26, 2023 8:56 PM
> >
> > On Mon, Jun 26, 2023 at 08:34:26AM +0000, Liu, Yi L wrote:
> > > > From: Jason Gunthorpe <jgg@nvidia.com>
> > > > Sent: Saturday, June 24, 2023 12:15 AM
> > >
> > > > >  }
> > > > >
> > > > > +static void vfio_device_get_kvm_safe(struct vfio_device_file *df)
> > > > > +{
> > > > > +	spin_lock(&df->kvm_ref_lock);
> > > > > +	if (df->kvm)
> > > > > +		_vfio_device_get_kvm_safe(df->device, df->kvm);
> > > > > +	spin_unlock(&df->kvm_ref_lock);
> > > > > +}
> > > >
> > > > I'm surprised symbol_get() can be called from a spinlock, but it sure
> > > > looks like it can..
> > > >
> > > > Also moving the if kvm is null test into _vfio_device_get_kvm_safe()
> > > > will save a few lines.
> > > >
> > > > Also shouldn't be called _vfio_device...
> > >
> > > Ah, any suggestion on the naming? How about vfio_device_get_kvm_safe_locked()?
> >
> > I thought you were using _df_ now for these functions?
> >
> 
> I see. Your point is passing df to _vfio_device_get_kvm_safe(() and
> test the df->kvm within it.  Hence rename it to be _df_. I think group
> path should be ok with this change as well. Let me make it.

To pass vfio_device_file to _vfio_device_get_kvm_safe(), needs to make
the below changes to the group path. If just wants to test null kvm in the
_vfio_device_get_kvm_safe(), maybe simpler to keep the current parameters
and just move the null kvm test within this function. Is it?

diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
index 41a09a2df690..c2e880c15c44 100644
--- a/drivers/vfio/group.c
+++ b/drivers/vfio/group.c
@@ -157,15 +157,15 @@ static int vfio_group_ioctl_set_container(struct vfio_group *group,
 	return ret;
 }
 
-static void vfio_device_group_get_kvm_safe(struct vfio_device *device)
+static void vfio_device_group_get_kvm_safe(struct vfio_device_file *df)
 {
-	spin_lock(&device->group->kvm_ref_lock);
-	if (!device->group->kvm)
-		goto unlock;
-
-	_vfio_device_get_kvm_safe(device, device->group->kvm);
+	struct vfio_device *device = df->device;
 
-unlock:
+	spin_lock(&device->group->kvm_ref_lock);
+	spin_lock(&df->kvm_ref_lock);
+	df->kvm = device->group->kvm;
+	_vfio_df_get_kvm_safe(df);
+	spin_unlock(&df->kvm_ref_lock);
 	spin_unlock(&device->group->kvm_ref_lock);
 }
 
@@ -189,7 +189,7 @@ static int vfio_df_group_open(struct vfio_device_file *df)
 	 * the pointer in the device for use by drivers.
 	 */
 	if (device->open_count == 0)
-		vfio_device_group_get_kvm_safe(device);
+		vfio_device_group_get_kvm_safe(df);
 
 	df->iommufd = device->group->iommufd;
 	if (df->iommufd && vfio_device_is_noiommu(device) && device->open_count == 0) {
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index fb8f2fac3d23..066766d43bdc 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -340,11 +340,10 @@ enum { vfio_noiommu = false };
 #endif
 
 #ifdef CONFIG_HAVE_KVM
-void _vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm);
+void _vfio_df_get_kvm_safe(struct vfio_device_file *df);
 void vfio_device_put_kvm(struct vfio_device *device);
 #else
-static inline void _vfio_device_get_kvm_safe(struct vfio_device *device,
-					     struct kvm *kvm)
+static inline void _vfio_df_get_kvm_safe(struct vfio_device_file *df)
 {
 }
 
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 8a9ebcc6980b..4e6ea2943d28 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -373,14 +373,22 @@ void vfio_unregister_group_dev(struct vfio_device *device)
 EXPORT_SYMBOL_GPL(vfio_unregister_group_dev);
 
 #ifdef CONFIG_HAVE_KVM
-void _vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm)
+void _vfio_df_get_kvm_safe(struct vfio_device_file *df)
 {
+	struct vfio_device *device = df->device;
 	void (*pfn)(struct kvm *kvm);
 	bool (*fn)(struct kvm *kvm);
+	struct kvm *kvm;
 	bool ret;
 
+	lockdep_assert_held(&df->kvm_ref_lock);
 	lockdep_assert_held(&device->dev_set->lock);
 
+	kvm = df->kvm;
+
+	if (!kvm)
+		return;
+
 	pfn = symbol_get(kvm_put_kvm);
 	if (WARN_ON(!pfn))
 		return;
Jason Gunthorpe June 28, 2023, 2:34 p.m. UTC | #13
On Mon, Jun 26, 2023 at 02:51:29PM +0000, Liu, Yi L wrote:
> > > >
> > > > Ah, any suggestion on the naming? How about vfio_device_get_kvm_safe_locked()?
> > >
> > > I thought you were using _df_ now for these functions?
> > >
> > 
> > I see. Your point is passing df to _vfio_device_get_kvm_safe(() and
> > test the df->kvm within it.  Hence rename it to be _df_. I think group
> > path should be ok with this change as well. Let me make it.
> 
> To pass vfio_device_file to _vfio_device_get_kvm_safe(), needs to make
> the below changes to the group path. If just wants to test null kvm in the
> _vfio_device_get_kvm_safe(), maybe simpler to keep the current parameters
> and just move the null kvm test within this function. Is it?

This does seem a bit nicer, yes

> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 8a9ebcc6980b..4e6ea2943d28 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -373,14 +373,22 @@ void vfio_unregister_group_dev(struct vfio_device *device)
>  EXPORT_SYMBOL_GPL(vfio_unregister_group_dev);
>  
>  #ifdef CONFIG_HAVE_KVM
> -void _vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm)
> +void _vfio_df_get_kvm_safe(struct vfio_device_file *df)

But still avoid the leading _ here

Jason
Yi Liu June 28, 2023, 2:41 p.m. UTC | #14
> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Wednesday, June 28, 2023 10:34 PM
> 
> On Mon, Jun 26, 2023 at 02:51:29PM +0000, Liu, Yi L wrote:
> > > > >
> > > > > Ah, any suggestion on the naming? How about
> vfio_device_get_kvm_safe_locked()?
> > > >
> > > > I thought you were using _df_ now for these functions?
> > > >
> > >
> > > I see. Your point is passing df to _vfio_device_get_kvm_safe(() and
> > > test the df->kvm within it.  Hence rename it to be _df_. I think group
> > > path should be ok with this change as well. Let me make it.
> >
> > To pass vfio_device_file to _vfio_device_get_kvm_safe(), needs to make
> > the below changes to the group path. If just wants to test null kvm in the
> > _vfio_device_get_kvm_safe(), maybe simpler to keep the current parameters
> > and just move the null kvm test within this function. Is it?
> 
> This does seem a bit nicer, yes
> 
> > diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> > index 8a9ebcc6980b..4e6ea2943d28 100644
> > --- a/drivers/vfio/vfio_main.c
> > +++ b/drivers/vfio/vfio_main.c
> > @@ -373,14 +373,22 @@ void vfio_unregister_group_dev(struct vfio_device *device)
> >  EXPORT_SYMBOL_GPL(vfio_unregister_group_dev);
> >
> >  #ifdef CONFIG_HAVE_KVM
> > -void _vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm)
> > +void _vfio_df_get_kvm_safe(struct vfio_device_file *df)
> 
> But still avoid the leading _ here

Ok, I'll move the kvm pointer test to _vfio_device_get_kvm_safe()
And also rename it as vfio_device_get_kvm_safe()

Regards,
Yi Liu
diff mbox series

Patch

diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
index 1c640016a824..a4498ddbe774 100644
--- a/drivers/vfio/device_cdev.c
+++ b/drivers/vfio/device_cdev.c
@@ -3,6 +3,7 @@ 
  * Copyright (c) 2023 Intel Corporation.
  */
 #include <linux/vfio.h>
+#include <linux/iommufd.h>
 
 #include "vfio.h"
 
@@ -44,6 +45,128 @@  int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep)
 	return ret;
 }
 
+static void vfio_device_get_kvm_safe(struct vfio_device_file *df)
+{
+	spin_lock(&df->kvm_ref_lock);
+	if (df->kvm)
+		_vfio_device_get_kvm_safe(df->device, df->kvm);
+	spin_unlock(&df->kvm_ref_lock);
+}
+
+void vfio_df_cdev_close(struct vfio_device_file *df)
+{
+	struct vfio_device *device = df->device;
+
+	/*
+	 * In the time of close, there is no contention with another one
+	 * changing this flag.  So read df->access_granted without lock
+	 * and no smp_load_acquire() is ok.
+	 */
+	if (!df->access_granted)
+		return;
+
+	mutex_lock(&device->dev_set->lock);
+	vfio_df_close(df);
+	vfio_device_put_kvm(device);
+	iommufd_ctx_put(df->iommufd);
+	device->cdev_opened = false;
+	mutex_unlock(&device->dev_set->lock);
+	vfio_device_unblock_group(device);
+}
+
+static struct iommufd_ctx *vfio_get_iommufd_from_fd(int fd)
+{
+	struct iommufd_ctx *iommufd;
+	struct fd f;
+
+	f = fdget(fd);
+	if (!f.file)
+		return ERR_PTR(-EBADF);
+
+	iommufd = iommufd_ctx_from_file(f.file);
+
+	fdput(f);
+	return iommufd;
+}
+
+long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
+				struct vfio_device_bind_iommufd __user *arg)
+{
+	struct vfio_device *device = df->device;
+	struct vfio_device_bind_iommufd bind;
+	unsigned long minsz;
+	int ret;
+
+	static_assert(__same_type(arg->out_devid, df->devid));
+
+	minsz = offsetofend(struct vfio_device_bind_iommufd, out_devid);
+
+	if (copy_from_user(&bind, arg, minsz))
+		return -EFAULT;
+
+	if (bind.argsz < minsz || bind.flags || bind.iommufd < 0)
+		return -EINVAL;
+
+	/* BIND_IOMMUFD only allowed for cdev fds */
+	if (df->group)
+		return -EINVAL;
+
+	ret = vfio_device_block_group(device);
+	if (ret)
+		return ret;
+
+	mutex_lock(&device->dev_set->lock);
+	/* one device cannot be bound twice */
+	if (df->access_granted) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	df->iommufd = vfio_get_iommufd_from_fd(bind.iommufd);
+	if (IS_ERR(df->iommufd)) {
+		ret = PTR_ERR(df->iommufd);
+		df->iommufd = NULL;
+		goto out_unlock;
+	}
+
+	/*
+	 * Before the device open, get the KVM pointer currently
+	 * associated with the device file (if there is) and obtain
+	 * a reference.  This reference is held until device closed.
+	 * Save the pointer in the device for use by drivers.
+	 */
+	vfio_device_get_kvm_safe(df);
+
+	ret = vfio_df_open(df);
+	if (ret)
+		goto out_put_kvm;
+
+	ret = copy_to_user(&arg->out_devid, &df->devid,
+			   sizeof(df->devid)) ? -EFAULT : 0;
+	if (ret)
+		goto out_close_device;
+
+	/*
+	 * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
+	 * read/write/mmap
+	 */
+	smp_store_release(&df->access_granted, true);
+	device->cdev_opened = true;
+	mutex_unlock(&device->dev_set->lock);
+	return 0;
+
+out_close_device:
+	vfio_df_close(df);
+out_put_kvm:
+	vfio_device_put_kvm(device);
+	iommufd_ctx_put(df->iommufd);
+	df->iommufd = NULL;
+out_unlock:
+	mutex_unlock(&device->dev_set->lock);
+	vfio_device_unblock_group(device);
+	return ret;
+}
+
 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 d12b5b524bfc..42de40d2cd4d 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -287,6 +287,9 @@  static inline void vfio_device_del(struct vfio_device *device)
 }
 
 int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep);
+void vfio_df_cdev_close(struct vfio_device_file *df);
+long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
+				struct vfio_device_bind_iommufd __user *arg);
 int vfio_cdev_init(struct class *device_class);
 void vfio_cdev_cleanup(void);
 #else
@@ -310,6 +313,16 @@  static inline int vfio_device_fops_cdev_open(struct inode *inode,
 	return 0;
 }
 
+static inline void vfio_df_cdev_close(struct vfio_device_file *df)
+{
+}
+
+static inline long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
+					      struct vfio_device_bind_iommufd __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 ef55af75f459..9ba4d420eda2 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -572,6 +572,8 @@  static int vfio_device_fops_release(struct inode *inode, struct file *filep)
 
 	if (df->group)
 		vfio_df_group_close(df);
+	else
+		vfio_df_cdev_close(df);
 
 	vfio_device_put_registration(device);
 
@@ -1145,6 +1147,9 @@  static long vfio_device_fops_unl_ioctl(struct file *filep,
 	struct vfio_device *device = df->device;
 	int ret;
 
+	if (cmd == VFIO_DEVICE_BIND_IOMMUFD)
+		return vfio_df_ioctl_bind_iommufd(df, (void __user *)arg);
+
 	/* Paired with smp_store_release() following vfio_df_open() */
 	if (!smp_load_acquire(&df->access_granted))
 		return -EINVAL;
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 83cc5dc28b7a..e80a8ac86e46 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -66,6 +66,7 @@  struct vfio_device {
 	struct iommufd_device *iommufd_device;
 	bool iommufd_attached;
 #endif
+	bool cdev_opened:1;
 };
 
 /**
@@ -170,7 +171,7 @@  vfio_iommufd_device_hot_reset_devid(struct vfio_device *vdev,
 
 static inline bool vfio_device_cdev_opened(struct vfio_device *device)
 {
-	return false;
+	return device->cdev_opened;
 }
 
 /**
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index f753124e1c82..7296012b7f36 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -194,6 +194,33 @@  struct vfio_group_status {
 
 /* --------------- IOCTLs for DEVICE file descriptors --------------- */
 
+/*
+ * VFIO_DEVICE_BIND_IOMMUFD - _IOR(VFIO_TYPE, VFIO_BASE + 18,
+ *				   struct vfio_device_bind_iommufd)
+ * @argsz:	 User filled size of this data.
+ * @flags:	 Must be 0.
+ * @iommufd:	 iommufd to bind.
+ * @out_devid:	 The device id generated by this bind. devid is a handle for
+ *		 this device/iommufd bond and can be used in IOMMUFD commands.
+ *
+ * Bind a vfio_device to the specified iommufd.
+ *
+ * User is restricted from accessing the device before the binding operation
+ * is completed.
+ *
+ * Unbind is automatically conducted when device fd is closed.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+struct vfio_device_bind_iommufd {
+	__u32		argsz;
+	__u32		flags;
+	__s32		iommufd;
+	__u32		out_devid;
+};
+
+#define VFIO_DEVICE_BIND_IOMMUFD	_IO(VFIO_TYPE, VFIO_BASE + 18)
+
 /**
  * VFIO_DEVICE_GET_INFO - _IOR(VFIO_TYPE, VFIO_BASE + 7,
  *						struct vfio_device_info)