Re: [PATCH v4 09/22] iommu: Introduce cache_invalidate API

[Jonathan Cameron]

On Sun, 9 Jun 2019 06:44:09 -0700
Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> wrote:

> From: Liu Yi L <yi.l.liu@xxxxxxxxx>
> 
> 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@xxxxxxxxx>
> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
Some comment ordering nitpicks.  Nothing important.

Jonathan

> ---
>  drivers/iommu/iommu.c      |  10 +++++
>  include/linux/iommu.h      |  14 ++++++
>  include/uapi/linux/iommu.h | 110 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 134 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 4496ccd..1758b57 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1638,6 +1638,16 @@ 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)
> +{
> +	if (unlikely(!domain->ops->cache_invalidate))
> +		return -ENODEV;
> +
> +	return domain->ops->cache_invalidate(domain, dev, inv_info);
> +}
> +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 d3edb10..7a37336 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -266,6 +266,7 @@ struct page_response_msg {
>   * @page_response: handle page request response
>   * @attach_pasid_table: attach a pasid table
>   * @detach_pasid_table: detach the pasid table
> + * @cache_invalidate: invalidate translation caches
>   * @pgsize_bitmap: bitmap of all possible supported page sizes
>   */
>  struct iommu_ops {
> @@ -330,6 +331,8 @@ struct iommu_ops {
>  	void (*detach_pasid_table)(struct iommu_domain *domain);
>  
>  	int (*page_response)(struct device *dev, struct page_response_msg *msg);
> +	int (*cache_invalidate)(struct iommu_domain *domain, struct device *dev,
> +				struct iommu_cache_invalidate_info *inv_info);
>  
>  	unsigned long pgsize_bitmap;
>  };
> @@ -442,6 +445,9 @@ 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,
> @@ -986,6 +992,14 @@ static inline int iommu_sva_get_pasid(struct iommu_sva *handle)
>  static inline
>  void iommu_detach_pasid_table(struct iommu_domain *domain) {}
>  
> +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 */
>  
>  #ifdef CONFIG_IOMMU_DEBUGFS
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index 3976767..ca4b753 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -167,4 +167,114 @@ 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 */
> +	IOMMU_INV_GRANU_NR,	/* number of invalidation granularities */
> +};
> +
> +/**
> + * struct iommu_inv_addr_info - Address Selective Invalidation Structure
> + *
> + * @flags: indicates the granularity of the address-selective invalidation
> + * - If the PASID bit is set, the @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.
> + * - The 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

Parameter ordering should match between docs and structure.
Might make more sense in some ways to not do so but the kernel-doc
guid states
"The kernel-doc data structure comments describe each member of the structure,
in order, with the @member: descriptions. "

> + * @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;
> +};
> +
> +/**
> + * struct iommu_inv_pasid_info - PASID Selective Invalidation Structure
> + *
> + * @flags: indicates the granularity of the PASID-selective invalidation
> + * - If the PASID bit is set, the @pasid field is populated and the invalidation
> + *   relates to cache entries tagged with this PASID and matching the address
> + *   range.
> + * - If the ARCHID bit is set, the @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.
> + * - At least one of PASID or ARCHID must be set.
> + * @pasid: process address space ID
> + * @archid: architecture-specific ID
Ordering of parameters is different from below.
> + */
> +struct iommu_inv_pasid_info {
> +#define IOMMU_INV_PASID_FLAGS_PASID	(1 << 0)
> +#define IOMMU_INV_PASID_FLAGS_ARCHID	(1 << 1)
> +	__u32	flags;
> +	__u32	archid;
> +	__u64	pasid;
> +};
> +
> +/**
> + * struct iommu_cache_invalidate_info - First level/stage invalidation
> + *     information
> + * @version: API version of this structure
> + * @cache: bitfield that allows to select which caches to invalidate
> + * @granularity: defines the lowest granularity used for the invalidation:
> + *     domain > PASID > addr
> + * @padding: reserved for future use (should be zero)
> + * @pasid_info: invalidation data when @granularity is %IOMMU_INV_GRANU_PASID
> + * @addr_info: invalidation data when @granularity is %IOMMU_INV_GRANU_ADDR
> + *
> + * Not all the combinations of cache/granularity are valid:
> + *
> + * +--------------+---------------+---------------+---------------+
> + * | type /       |   DEV_IOTLB   |     IOTLB     |      PASID    |
> + * | granularity  |               |               |      cache    |
> + * +==============+===============+===============+===============+
> + * | DOMAIN       |       N/A     |       Y       |       Y       |
> + * +--------------+---------------+---------------+---------------+
> + * | PASID        |       Y       |       Y       |       Y       |
> + * +--------------+---------------+---------------+---------------+
> + * | ADDR         |       Y       |       Y       |       N/A     |
> + * +--------------+---------------+---------------+---------------+
> + *
> + * Invalidations by %IOMMU_INV_GRANU_DOMAIN don't take any argument other than
> + * @version and @cache.
> + *
> + * If multiple cache types are invalidated simultaneously, they all
> + * must support the used granularity.
> + */
> +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 */
> +#define IOMMU_CACHE_INV_TYPE_NR		(3)
> +	__u8	cache;
> +	__u8	granularity;
> +	__u8	padding[2];
> +	union {
> +		struct iommu_inv_pasid_info pasid_info;
> +		struct iommu_inv_addr_info addr_info;
> +	};
> +};
> +
>  #endif /* _UAPI_IOMMU_H */