Re: [PATCH v5 18/19] vfio: Compile group optionally

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> From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> Sent: Monday, February 27, 2023 7:12 PM
> 
> group code is not needed for vfio device cdev, so with vfio device cdev
> introduced, the group infrastructures can be compiled out if only cdev
> is needed.
> 
> Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> ---
>  drivers/vfio/Kconfig  | 14 +++++++++
>  drivers/vfio/Makefile |  2 +-
>  drivers/vfio/vfio.h   | 72
> +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/vfio.h  | 24 ++++++++++++++-
>  4 files changed, 110 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
> index 169762316513..c3ab06c314ea 100644
> --- a/drivers/vfio/Kconfig
> +++ b/drivers/vfio/Kconfig
> @@ -4,6 +4,8 @@ menuconfig VFIO
>  	select IOMMU_API
>  	depends on IOMMUFD || !IOMMUFD
>  	select INTERVAL_TREE
> +	select VFIO_GROUP if SPAPR_TCE_IOMMU
> +	select VFIO_DEVICE_CDEV if !VFIO_GROUP && (X86 || S390 || ARM || ARM64)

Got below warning when IOMMUFD=n, VFIO_GROUP=n. so may remove
this select or needs to let VFIO_DEVICE_CDEV select IOMMUFD instead of
depends on IOMMUFD.

WARNING: unmet direct dependencies detected for VFIO_DEVICE_CDEV
  Depends on [n]: VFIO [=m] && IOMMUFD [=n]
  Selected by [m]:
  - VFIO [=m] && (IOMMUFD [=n] || !IOMMUFD [=n]) && !VFIO_GROUP [=n]

>  	select VFIO_CONTAINER if IOMMUFD=n

Needs to be if IOMMUFD=n && VFIO_GROUP, otherwise vfio container
is compiled even VFIO_GROUP=n.

>  	help
>  	  VFIO provides a framework for secure userspace device drivers.
> @@ -15,6 +17,7 @@ if VFIO
>  config VFIO_DEVICE_CDEV
>  	bool "Support for the VFIO cdev /dev/vfio/devices/vfioX"
>  	depends on IOMMUFD && (X86 || S390 || ARM || ARM64)

depends on IOMMUFD have warning when IOMMUFD=n and VFIO_GROUP=n.

> +	default !VFIO_GROUP
>  	help
>  	  The VFIO device cdev is another way for userspace to get device
>  	  access. Userspace gets device fd by opening device cdev under
> @@ -24,9 +27,20 @@ config VFIO_DEVICE_CDEV
> 
>  	  If you don't know what to do here, say N.
> 
> +config VFIO_GROUP
> +	bool "Support for the VFIO group /dev/vfio/$group_id"
> +	default y
> +	help
> +	   VFIO group support provides the traditional model for accessing
> +	   devices through VFIO and is used by the majority of userspace
> +	   applications and drivers making use of VFIO.
> +
> +	   If you don't know what to do here, say Y.
> +
>  config VFIO_CONTAINER
>  	bool "Support for the VFIO container /dev/vfio/vfio"
>  	select VFIO_IOMMU_TYPE1 if MMU && (X86 || S390 || ARM ||
> ARM64)
> +	depends on VFIO_GROUP
>  	default y
>  	help
>  	  The VFIO container is the classic interface to VFIO for establishing
> diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
> index 245394aeb94b..57c3515af606 100644
> --- a/drivers/vfio/Makefile
> +++ b/drivers/vfio/Makefile
> @@ -2,9 +2,9 @@
>  obj-$(CONFIG_VFIO) += vfio.o
> 
>  vfio-y += vfio_main.o \
> -	  group.o \
>  	  iova_bitmap.o
>  vfio-$(CONFIG_VFIO_DEVICE_CDEV) += device_cdev.o
> +vfio-$(CONFIG_VFIO_GROUP) += group.o
>  vfio-$(CONFIG_IOMMUFD) += iommufd.o
>  vfio-$(CONFIG_VFIO_CONTAINER) += container.o
>  vfio-$(CONFIG_VFIO_VIRQFD) += virqfd.o
> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> index 5a1ceb014779..a7b88521bf48 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -62,6 +62,7 @@ enum vfio_group_type {
>  	VFIO_NO_IOMMU,
>  };
> 
> +#if IS_ENABLED(CONFIG_VFIO_GROUP)
>  struct vfio_group {
>  	struct device 			dev;
>  	struct cdev			cdev;
> @@ -107,6 +108,77 @@ void vfio_group_set_kvm(struct vfio_group *group,
> struct kvm *kvm);
>  bool vfio_device_has_container(struct vfio_device *device);
>  int __init vfio_group_init(void);
>  void vfio_group_cleanup(void);
> +#else
> +struct vfio_group;
> +
> +static inline int vfio_device_block_group(struct vfio_device *device)
> +{
> +	return 0;
> +}
> +
> +static inline void vfio_device_unblock_group(struct vfio_device *device)
> +{
> +}
> +
> +static inline int vfio_device_set_group(struct vfio_device *device,
> +					enum vfio_group_type type)
> +{
> +	return 0;
> +}
> +
> +static inline void vfio_device_remove_group(struct vfio_device *device)
> +{
> +}
> +
> +static inline void vfio_device_group_register(struct vfio_device *device)
> +{
> +}
> +
> +static inline void vfio_device_group_unregister(struct vfio_device *device)
> +{
> +}
> +
> +static inline int vfio_device_group_use_iommu(struct vfio_device *device)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static inline void vfio_device_group_unuse_iommu(struct vfio_device
> *device)
> +{
> +}
> +
> +static inline void vfio_device_group_close(struct vfio_device_file *df)
> +{
> +}
> +
> +static inline struct vfio_group *vfio_group_from_file(struct file *file)
> +{
> +	return NULL;
> +}
> +
> +static inline bool vfio_group_enforced_coherent(struct vfio_group *group)
> +{
> +	return true;
> +}
> +
> +static inline void vfio_group_set_kvm(struct vfio_group *group, struct kvm
> *kvm)
> +{
> +}
> +
> +static inline bool vfio_device_has_container(struct vfio_device *device)
> +{
> +	return false;
> +}
> +
> +static inline int __init vfio_group_init(void)
> +{
> +	return 0;
> +}
> +
> +static inline void vfio_group_cleanup(void)
> +{
> +}
> +#endif /* CONFIG_VFIO_GROUP */
> 
>  #if IS_ENABLED(CONFIG_VFIO_CONTAINER)
>  /**
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index ce390533cb30..d12384824656 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -43,7 +43,9 @@ struct vfio_device {
>  	 */
>  	const struct vfio_migration_ops *mig_ops;
>  	const struct vfio_log_ops *log_ops;
> +#if IS_ENABLED(CONFIG_VFIO_GROUP)
>  	struct vfio_group *group;
> +#endif
>  	struct vfio_device_set *dev_set;
>  	struct list_head dev_set_list;
>  	unsigned int migration_flags;
> @@ -58,8 +60,10 @@ struct vfio_device {
>  	refcount_t refcount;	/* user count on registered device*/
>  	unsigned int open_count;
>  	struct completion comp;
> +#if IS_ENABLED(CONFIG_VFIO_GROUP)
>  	struct list_head group_next;
>  	struct list_head iommu_entry;
> +#endif
>  	struct iommufd_access *iommufd_access;
>  	void (*put_kvm)(struct kvm *kvm);
>  #if IS_ENABLED(CONFIG_IOMMUFD)
> @@ -257,12 +261,30 @@ int vfio_mig_get_next_state(struct vfio_device
> *device,
>  /*
>   * External user API
>   */
> +#if IS_ENABLED(CONFIG_VFIO_GROUP)
>  struct iommu_group *vfio_file_iommu_group(struct file *file);
>  bool vfio_file_is_group(struct file *file);
> +bool vfio_file_has_dev(struct file *file, struct vfio_device *device);
> +#else
> +static inline struct iommu_group *vfio_file_iommu_group(struct file *file)
> +{
> +	return NULL;
> +}
> +
> +static inline bool vfio_file_is_group(struct file *file)
> +{
> +	return false;
> +}
> +
> +static inline bool vfio_file_has_dev(struct file *file,
> +				     struct vfio_device *device)
> +{
> +	return false;
> +}
> +#endif
>  bool vfio_file_is_valid(struct file *file);
>  bool vfio_file_enforced_coherent(struct file *file);
>  void vfio_file_set_kvm(struct file *file, struct kvm *kvm);
> -bool vfio_file_has_dev(struct file *file, struct vfio_device *device);
> 
>  #define VFIO_PIN_PAGES_MAX_ENTRIES	(PAGE_SIZE/sizeof(unsigned
> long))
> 
> --
> 2.34.1





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