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

[Auger Eric <eric.auger@redhat.com>]

Hi Jean,

On 3/5/19 4:23 PM, Jean-Philippe Brucker wrote:
> On 18/02/2019 13:54, Eric Auger wrote:
>> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
>>
>> 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@arm.com>
>> Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
>> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
>> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>
>> ---
>>
>> 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
sure
> 
>>   */
>>  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:
oups
> 
> Reviewed-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Thanks!

Eric

> 
>> +}
>> +
>>  #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 */
>>
>