Re: [PATCH v3 02/16] iommu: Introduce cache_invalidate API

Auger Eric
2019-05-13T16:51:02Z

Hi Jean-Philippe,

On 5/13/19 1:20 PM, Jean-Philippe Brucker wrote:
> Hi Eric,
>
> On 13/05/2019 10:14, Auger Eric wrote:
>> I noticed my qemu integration was currently incorrectly using PASID
>> invalidation for ASID based invalidation (SMMUV3 Stage1 CMD_TLBI_NH_ASID
>> invalidation command). So I think we also need ARCHID invalidation.
>> Sorry for the late notice.
>>>
>>> +/* defines the granularity of the invalidation */
>>> +enum iommu_inv_granularity {
>>> + IOMMU_INV_GRANU_DOMAIN, /* domain-selective invalidation */
>> IOMMU_INV_GRANU_ARCHID, /* archid-selective invalidation */
>>> + IOMMU_INV_GRANU_PASID, /* pasid-selective invalidation */
>
> In terms of granularity, these values have the same meaning: invalidate
> the whole address space of a context. Then you can communicate two
> things using the same struct:
> * If ATS is enables an Arm host needs to invalidate all ATC entries
> using PASID.
> * If BTM isn't used by the guest, the host needs to invalidate all TLB
> entries using ARCHID.
>
> Rather than introducing a new granule here, could we just add an archid
> field to the struct associated with IOMMU_INV_GRANU_PASID? Something like...
>
>>> + IOMMU_INV_GRANU_ADDR, /* page-selective invalidation */
>>> + IOMMU_INVAL_GRANU_NR, /* number of invalidation granularities */
>>> +};
>>> +
>>> +/**
>>> + * 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;
>>> +};
>
> 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;
> };
I agree it does the job now. However it looks a bit strange to do a
PASID based invalidation in my case - SMMUv3 nested stage - where I
don't have any PASID involved.

Couldn't we call it context based invalidation then? A context can be
tagged by a PASID or/and an ARCHID.

Domain invalidation would invalidate all the contexts belonging to that
domain.

Thanks

Eric
>
>>> +
>>> +/**
>>> + * 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 |
>> * ARCHID | N/A | Y | N/A |
>>
>>> + * PASID | Y | Y | Y |
>>> + * ADDR | Y | Y | N/A |
>>> + *
>>> + * Invalidations by %IOMMU_INV_GRANU_ADDR use field @addr_info.
>> * Invalidations by %IOMMU_INV_GRANU_ARCHID use field @archid.
>>> + * Invalidations by %IOMMU_INV_GRANU_PASID use field @pasid.
>>> + * Invalidations by %IOMMU_INV_GRANU_DOMAIN don't take any argument.
>>> + *
>>> + * 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_TYPE_NR (3)
>>> + __u8 cache;
>>> + __u8 granularity;
>>> + __u8 padding[2];
>>> + union {
>>> + __u64 pasid;
>> __u32 archid;
>
> struct iommu_inv_pasid_info pasid_info;
>
> Thanks,
> Jean
>
>>
>> Thanks
>>
>> Eric
>>> + struct iommu_inv_addr_info addr_info;
>>> + };
>>> +};
>>> +
>>> +
>>> #endif /* _UAPI_IOMMU_H */
>>>