Re: [PATCH v4 04/22] iommu: Introduce attach/detach_pasid_table API

[Jean-Philippe Brucker]

On 18/02/2019 13:54, Eric Auger wrote:
> From: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> 
> In virtualization use case, when a guest is assigned
> a PCI host device, protected by a virtual IOMMU on the guest,
> the physical IOMMU must be programmed to be consistent with
> the guest mappings. If the physical IOMMU supports two
> translation stages it makes sense to program guest mappings
> onto the first stage/level (ARM/Intel terminology) while the host
> owns the stage/level 2.
> 
> In that case, it is mandated to trap on guest configuration
> settings and pass those to the physical iommu driver.
> 
> This patch adds a new API to the iommu subsystem that allows
> to set/unset the pasid table information.
> 
> A generic iommu_pasid_table_config struct is introduced in
> a new iommu.h uapi header. This is going to be used by the VFIO
> user API.
> 
> Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
> Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxxxxxxxx>
> Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
> 
> ---
> 
> This patch generalizes the API introduced by Jacob & co-authors in
> https://lwn.net/Articles/754331/
> 
> v3 -> v4:
> - s/set_pasid_table/attach_pasid_table
> - restore detach_pasid_table. Detach can be used on unwind path.
> - add padding
> - remove @abort
> - signature used for config and format
> - add comments for fields in the SMMU struct
> 
> v2 -> v3:
> - replace unbind/bind by set_pasid_table
> - move table pointer and pasid bits in the generic part of the struct
> 
> v1 -> v2:
> - restore the original pasid table name
> - remove the struct device * parameter in the API
> - reworked iommu_pasid_smmuv3
> ---
>  drivers/iommu/iommu.c      | 19 +++++++++++++++
>  include/linux/iommu.h      | 22 ++++++++++++++++++
>  include/uapi/linux/iommu.h | 47 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 88 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index c297cdcf7f89..b3adb77cb14c 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1545,6 +1545,25 @@ int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(iommu_attach_device);
>  
> +int iommu_attach_pasid_table(struct iommu_domain *domain,
> +			     struct iommu_pasid_table_config *cfg)
> +{
> +	if (unlikely(!domain->ops->attach_pasid_table))
> +		return -ENODEV;
> +
> +	return domain->ops->attach_pasid_table(domain, cfg);
> +}
> +EXPORT_SYMBOL_GPL(iommu_attach_pasid_table);
> +
> +void iommu_detach_pasid_table(struct iommu_domain *domain)
> +{
> +	if (unlikely(!domain->ops->detach_pasid_table))
> +		return;
> +
> +	domain->ops->detach_pasid_table(domain);
> +}
> +EXPORT_SYMBOL_GPL(iommu_detach_pasid_table);
> +
>  static void __iommu_detach_device(struct iommu_domain *domain,
>  				  struct device *dev)
>  {
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index b38e0c100940..7045e26f3a7d 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -187,6 +187,8 @@ struct iommu_resv_region {
>   * @domain_window_disable: Disable a particular window for a domain
>   * @of_xlate: add OF master IDs to iommu grouping
>   * @pgsize_bitmap: bitmap of all possible supported page sizes
> + * @attach_pasid_table: attach a pasid table
> + * @detach_pasid_table: detach the pasid table

Should go before pgsize_bitmap

>   */
>  struct iommu_ops {
>  	bool (*capable)(enum iommu_cap);
> @@ -229,6 +231,10 @@ struct iommu_ops {
>  	int (*of_xlate)(struct device *dev, struct of_phandle_args *args);
>  	bool (*is_attach_deferred)(struct iommu_domain *domain, struct device *dev);
>  
> +	int (*attach_pasid_table)(struct iommu_domain *domain,
> +				  struct iommu_pasid_table_config *cfg);
> +	void (*detach_pasid_table)(struct iommu_domain *domain);
> +
>  	unsigned long pgsize_bitmap;
>  };
>  
> @@ -339,6 +345,9 @@ extern int iommu_attach_device(struct iommu_domain *domain,
>  			       struct device *dev);
>  extern void iommu_detach_device(struct iommu_domain *domain,
>  				struct device *dev);
> +extern int iommu_attach_pasid_table(struct iommu_domain *domain,
> +				    struct iommu_pasid_table_config *cfg);
> +extern void iommu_detach_pasid_table(struct iommu_domain *domain);
>  extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
>  extern struct iommu_domain *iommu_get_dma_domain(struct device *dev);
>  extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
> @@ -777,6 +786,19 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
>  	return NULL;
>  }
>  
> +static inline
> +int iommu_attach_pasid_table(struct iommu_domain *domain,
> +			     struct iommu_pasid_table_config *cfg)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline
> +void iommu_detach_pasid_table(struct iommu_domain *domain)
> +{
> +	return -ENODEV;

No return here. With that fixed:

Reviewed-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>

> +}
> +
>  #endif /* CONFIG_IOMMU_API */
>  
>  #ifdef CONFIG_IOMMU_DEBUGFS
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index 7ebf23ed6ccb..e9065bfa5b24 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -112,4 +112,51 @@ struct iommu_fault {
>  		struct iommu_fault_page_request prm;
>  	};
>  };
> +
> +/**
> + * SMMUv3 Stream Table Entry stage 1 related information
> + * The PASID table is referred to as the context descriptor (CD) table.
> + *
> + * @s1fmt: STE s1fmt (format of the CD table: single CD, linear table
> +   or 2-level table)
> + * @s1dss: STE s1dss (specifies the behavior when pasid_bits != 0
> +   and no pasid is passed along with the incoming transaction)
> + * Please refer to the smmu 3.x spec (ARM IHI 0070A) for full details
> + */
> +struct iommu_pasid_smmuv3 {
> +#define PASID_TABLE_SMMUV3_CFG_VERSION_1 1
> +	__u32	version;
> +	__u8 s1fmt;
> +	__u8 s1dss;
> +	__u8 padding[2];
> +};
> +
> +/**
> + * PASID table data used to bind guest PASID table to the host IOMMU
> + * Note PASID table corresponds to the Context Table on ARM SMMUv3.
> + *
> + * @version: API version to prepare for future extensions
> + * @format: format of the PASID table
> + * @base_ptr: guest physical address of the PASID table
> + * @pasid_bits: number of PASID bits used in the PASID table
> + * @config: indicates whether the guest translation stage must
> + * be translated, bypassed or aborted.
> + */
> +struct iommu_pasid_table_config {
> +#define PASID_TABLE_CFG_VERSION_1 1
> +	__u32	version;
> +#define IOMMU_PASID_FORMAT_SMMUV3	1
> +	__u32	format;
> +	__u64	base_ptr;
> +	__u8	pasid_bits;
> +#define IOMMU_PASID_CONFIG_TRANSLATE	1
> +#define IOMMU_PASID_CONFIG_BYPASS	2
> +#define IOMMU_PASID_CONFIG_ABORT	3
> +	__u8	config;
> +	__u8    padding[6];
> +	union {
> +		struct iommu_pasid_smmuv3 smmuv3;
> +	};
> +};
> +
>  #endif /* _UAPI_IOMMU_H */
>