linux-kernel - Re: [PATCH v5 05/22] iommu: Introduce cache

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Date:   Mon, 18 Mar 2019 11:01:21 +0000
From:   Jean-Philippe Brucker <jean-philippe.brucker@....com>
To:     Auger Eric <eric.auger@...hat.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc:     "eric.auger.pro@...il.com" <eric.auger.pro@...il.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "kvmarm@...ts.cs.columbia.edu" <kvmarm@...ts.cs.columbia.edu>,
        "joro@...tes.org" <joro@...tes.org>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "yi.l.liu@...ux.intel.com" <yi.l.liu@...ux.intel.com>,
        Will Deacon <Will.Deacon@....com>,
        Robin Murphy <Robin.Murphy@....com>,
        "kevin.tian@...el.com" <kevin.tian@...el.com>,
        "ashok.raj@...el.com" <ashok.raj@...el.com>,
        Marc Zyngier <Marc.Zyngier@....com>,
        Christoffer Dall <Christoffer.Dall@....com>,
        "peter.maydell@...aro.org" <peter.maydell@...aro.org>,
        Vincent Stehle <Vincent.Stehle@....com>
Subject: Re: [PATCH v5 05/22] iommu: Introduce cache_invalidate API

On 17/03/2019 16:43, Auger Eric wrote:
>>> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
>>> index 532a64075f23..e4c6a447e85a 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;
>>> +};
>>> +
>>> +/**
>>> + * 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;
>> just realized there is already a pasid field in the addr_info, do we
>> still need this?
> I think so. Either you do a PASID based invalidation and you directly
> use the pasid field or you do an address based invalidation and you use
> the addr_info where the pasid may or not be passed.

I guess a comment would be useful?

    - Invalidations by %IOMMU_INV_GRANU_ADDR use field @addr_info.
    - Invalidations by %IOMMU_INV_GRANU_PASID use field @pasid.
    - Invalidations by %IOMMU_INV_GRANU_DOMAIN don't take an argument.

Thanks,
Jean

> 
> Thanks
> 
> Eric
>>> +		struct iommu_inv_addr_info addr_info;
>>> +	};
>>> +};
>>> +
>>> +
>>>  #endif /* _UAPI_IOMMU_H */
>>
>> [Jacob Pan]
>>