linux-kernel - Re: [PATCH v3 02/16] iommu: Introduce cache

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Message-ID: <4094baf1-6cf5-a33b-4717-08ced0673c50@arm.com>
Date:   Tue, 14 May 2019 11:42:46 +0100
From:   Jean-Philippe Brucker <jean-philippe.brucker@....com>
To:     Auger Eric <eric.auger@...hat.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Alex Williamson <alex.williamson@...hat.com>
Cc:     "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Andriy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v3 02/16] iommu: Introduce cache_invalidate API

On 14/05/2019 08:46, Auger Eric wrote:
> Hi Jean,
> 
> On 5/13/19 7:09 PM, Jean-Philippe Brucker wrote:
>> On 13/05/2019 17:50, Auger Eric wrote:
>>>> 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.
>>
>> I think calling it "context" would be confusing as well (I shouldn't
>> have used it earlier), since VT-d uses that name for device table
>> entries (=STE on Arm SMMU). Maybe "addr_space"?
> yes you're right. Well we already pasid table table terminology so we
> can use it here as well - as long as we understand what purpose it
> serves ;-) - So OK for iommu_inv_pasid_info.
> 
> I think Jean understood we would keep pasid standalone field in
> iommu_cache_invalidate_info's union. I understand the struct
> iommu_inv_pasid_info now would replace it, correct?

Yes

Thanks,
Jean