Re: [PATCH v4 05/22] iommu: Introduce cache_invalidate API

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

Hi Kevin, Yi,

On 3/5/19 4:28 PM, Jean-Philippe Brucker wrote:
> On 18/02/2019 13:54, Eric Auger wrote:
>> From: "Liu, Yi L" <yi.l.liu@linux.intel.com>
>>
>> In any virtualization use case, when the first translation stage
>> is "owned" by the guest OS, the host IOMMU driver has no knowledge
>> of caching structure updates unless the guest invalidation activities
>> are trapped by the virtualizer and passed down to the host.
>>
>> Since the invalidation data are obtained from user space and will be
>> written into physical IOMMU, we must allow security check at various
>> layers. Therefore, generic invalidation data format are proposed here,
>> model specific IOMMU drivers need to convert them into their own format.
>>
>> Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
>> Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
>> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
>> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>
>> ---
>> v3 -> v4:
>> - full reshape of the API following Alex' comments
>>
>> v1 -> v2:
>> - add arch_id field
>> - renamed tlb_invalidate into cache_invalidate as this API allows
>>   to invalidate context caches on top of IOTLBs
>>
>> v1:
>> renamed sva_invalidate into tlb_invalidate and add iommu_ prefix in
>> header. Commit message reworded.
>> ---
>>  drivers/iommu/iommu.c      | 14 ++++++++
>>  include/linux/iommu.h      | 14 ++++++++
>>  include/uapi/linux/iommu.h | 71 ++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 99 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index b3adb77cb14c..bcb8eb15426c 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -1564,6 +1564,20 @@ void iommu_detach_pasid_table(struct iommu_domain *domain)
>>  }
>>  EXPORT_SYMBOL_GPL(iommu_detach_pasid_table);
>>  
>> +int iommu_cache_invalidate(struct iommu_domain *domain, struct device *dev,
>> +			   struct iommu_cache_invalidate_info *inv_info)
>> +{
>> +	int ret = 0;
>> +
>> +	if (unlikely(!domain->ops->cache_invalidate))
>> +		return -ENODEV;
>> +
>> +	ret = domain->ops->cache_invalidate(domain, dev, inv_info);
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_cache_invalidate);
>> +
>>  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 7045e26f3a7d..a3b879d0753c 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -189,6 +189,7 @@ struct iommu_resv_region {
>>   * @pgsize_bitmap: bitmap of all possible supported page sizes
>>   * @attach_pasid_table: attach a pasid table
>>   * @detach_pasid_table: detach the pasid table
>> + * @cache_invalidate: invalidate translation caches
>>   */
>>  struct iommu_ops {
>>  	bool (*capable)(enum iommu_cap);
>> @@ -235,6 +236,9 @@ struct iommu_ops {
>>  				  struct iommu_pasid_table_config *cfg);
>>  	void (*detach_pasid_table)(struct iommu_domain *domain);
>>  
>> +	int (*cache_invalidate)(struct iommu_domain *domain, struct device *dev,
>> +				struct iommu_cache_invalidate_info *inv_info);
>> +
>>  	unsigned long pgsize_bitmap;
>>  };
>>  
>> @@ -348,6 +352,9 @@ extern void iommu_detach_device(struct iommu_domain *domain,
>>  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 int iommu_cache_invalidate(struct iommu_domain *domain,
>> +				  struct device *dev,
>> +				  struct iommu_cache_invalidate_info *inv_info);
>>  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,
>> @@ -798,6 +805,13 @@ void iommu_detach_pasid_table(struct iommu_domain *domain)
>>  {
>>  	return -ENODEV;
>>  }
>> +static inline int
>> +iommu_cache_invalidate(struct iommu_domain *domain,
>> +		       struct device *dev,
>> +		       struct iommu_cache_invalidate_info *inv_info)
>> +{
>> +	return -ENODEV;
>> +}
>>  
>>  #endif /* CONFIG_IOMMU_API */
>>  
>> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
>> index e9065bfa5b24..ae41385b0a7e 100644
>> --- a/include/uapi/linux/iommu.h
>> +++ b/include/uapi/linux/iommu.h
>> @@ -159,4 +159,75 @@ struct iommu_pasid_table_config {
>>  	};
>>  };
>>  
>> +/* defines the granularity of the invalidation */
>> +enum iommu_inv_granularity {
>> +	IOMMU_INV_GRANU_DOMAIN,	/* domain-selective invalidation */
>> +	IOMMU_INV_GRANU_PASID,	/* pasid-selective invalidation */
>> +	IOMMU_INV_GRANU_ADDR,	/* page-selective invalidation */
>> +};
>> +
>> +/**
>> + * Address Selective Invalidation Structure
>> + *
>> + * @flags indicates the granularity of the address-selective invalidation
>> + * - if PASID bit is set, @pasid field is populated and the invalidation
>> + *   relates to cache entries tagged with this PASID and matching the
>> + *   address range.
>> + * - if ARCHID bit is set, @archid is populated and the invalidation relates
>> + *   to cache entries tagged with this architecture specific id and matching
>> + *   the address range.
>> + * - Both PASID and ARCHID can be set as they may tag different caches.
>> + * - if neither PASID or ARCHID is set, global addr invalidation applies
>> + * - LEAF flag indicates whether only the leaf PTE caching needs to be
>> + *   invalidated and other paging structure caches can be preserved.
>> + * @pasid: process address space id
>> + * @archid: architecture-specific id
>> + * @addr: first stage/level input address
>> + * @granule_size: page/block size of the mapping in bytes
>> + * @nb_granules: number of contiguous granules to be invalidated
>> + */
>> +struct iommu_inv_addr_info {
>> +#define IOMMU_INV_ADDR_FLAGS_PASID	(1 << 0)
>> +#define IOMMU_INV_ADDR_FLAGS_ARCHID	(1 << 1)
>> +#define IOMMU_INV_ADDR_FLAGS_LEAF	(1 << 2)
>> +	__u32	flags;
>> +	__u32	archid;
>> +	__u64	pasid;
>> +	__u64	addr;
>> +	__u64	granule_size;
>> +	__u64	nb_granules;
>> +};
> 
> Some fields don't need that many bytes, but I'm not sure it matters and
> I'd like to see if this version works for the x86 folks before bothering
> with such details. Looks good to me, from the SMMU perspective.
Does it fit your needs? - Thanks Jean for your feedback -

Thanks

Eric

> 
> Thanks,
> Jean
> 
>> +
>> +/**
>> + * First level/stage invalidation information
>> + * @cache: bitfield that allows to select which caches to invalidate
>> + * @granularity: defines the lowest granularity used for the invalidation:
>> + *     domain > pasid > addr
>> + *
>> + * Not all the combinations of cache/granularity make sense:
>> + *
>> + *         type |   DEV_IOTLB   |     IOTLB     |      PASID    |
>> + * granularity	|		|		|      cache	|
>> + * -------------+---------------+---------------+---------------+
>> + * DOMAIN	|	N/A	|       Y	|	Y	|
>> + * PASID	|	Y	|       Y	|	Y	|
>> + * ADDR		|       Y	|       Y	|	N/A	|
>> + */
>> +struct iommu_cache_invalidate_info {
>> +#define IOMMU_CACHE_INVALIDATE_INFO_VERSION_1 1
>> +	__u32	version;
>> +/* IOMMU paging structure cache */
>> +#define IOMMU_CACHE_INV_TYPE_IOTLB	(1 << 0) /* IOMMU IOTLB */
>> +#define IOMMU_CACHE_INV_TYPE_DEV_IOTLB	(1 << 1) /* Device IOTLB */
>> +#define IOMMU_CACHE_INV_TYPE_PASID	(1 << 2) /* PASID cache */
>> +	__u8	cache;
>> +	__u8	granularity;
>> +	__u8	padding[2];
>> +	union {
>> +		__u64	pasid;
>> +		struct iommu_inv_addr_info addr_info;
>> +	};
>> +};
>> +
>> +
>>  #endif /* _UAPI_IOMMU_H */
>>
>