linux-kernel - Re: [PATCH v14 13/13] iommu/smmuv3: Accept configs with more than one context descriptor

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Date:   Thu, 1 Apr 2021 15:20:23 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>,
        yuzenghui <yuzenghui@...wei.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>,
        "will@...nel.org" <will@...nel.org>,
        "maz@...nel.org" <maz@...nel.org>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "joro@...tes.org" <joro@...tes.org>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "tn@...ihalf.com" <tn@...ihalf.com>,
        zhukeqian <zhukeqian1@...wei.com>,
        "jacob.jun.pan@...ux.intel.com" <jacob.jun.pan@...ux.intel.com>,
        "yi.l.liu@...el.com" <yi.l.liu@...el.com>,
        wangxingang <wangxingang5@...wei.com>,
        jiangkunkun <jiangkunkun@...wei.com>,
        "jean-philippe@...aro.org" <jean-philippe@...aro.org>,
        "zhangfei.gao@...aro.org" <zhangfei.gao@...aro.org>,
        "zhangfei.gao@...il.com" <zhangfei.gao@...il.com>,
        "vivek.gautam@....com" <vivek.gautam@....com>,
        "nicoleotsuka@...il.com" <nicoleotsuka@...il.com>,
        lushenming <lushenming@...wei.com>,
        "vsethi@...dia.com" <vsethi@...dia.com>,
        "Wanghaibin (D)" <wanghaibin.wang@...wei.com>
Subject: Re: [PATCH v14 13/13] iommu/smmuv3: Accept configs with more than one
 context descriptor

Hi Shameer,
On 4/1/21 2:38 PM, Shameerali Kolothum Thodi wrote:
> 
> 
>> -----Original Message-----
>> From: Auger Eric [mailto:eric.auger@...hat.com]
>> Sent: 01 April 2021 12:49
>> To: yuzenghui <yuzenghui@...wei.com>
>> Cc: eric.auger.pro@...il.com; iommu@...ts.linux-foundation.org;
>> linux-kernel@...r.kernel.org; kvm@...r.kernel.org;
>> kvmarm@...ts.cs.columbia.edu; will@...nel.org; maz@...nel.org;
>> robin.murphy@....com; joro@...tes.org; alex.williamson@...hat.com;
>> tn@...ihalf.com; zhukeqian <zhukeqian1@...wei.com>;
>> jacob.jun.pan@...ux.intel.com; yi.l.liu@...el.com; wangxingang
>> <wangxingang5@...wei.com>; jiangkunkun <jiangkunkun@...wei.com>;
>> jean-philippe@...aro.org; zhangfei.gao@...aro.org; zhangfei.gao@...il.com;
>> vivek.gautam@....com; Shameerali Kolothum Thodi
>> <shameerali.kolothum.thodi@...wei.com>; nicoleotsuka@...il.com;
>> lushenming <lushenming@...wei.com>; vsethi@...dia.com; Wanghaibin (D)
>> <wanghaibin.wang@...wei.com>
>> Subject: Re: [PATCH v14 13/13] iommu/smmuv3: Accept configs with more than
>> one context descriptor
>>
>> Hi Zenghui,
>>
>> On 3/30/21 11:23 AM, Zenghui Yu wrote:
>>> Hi Eric,
>>>
>>> On 2021/2/24 4:56, Eric Auger wrote:
>>>> In preparation for vSVA, let's accept userspace provided configs
>>>> with more than one CD. We check the max CD against the host iommu
>>>> capability and also the format (linear versus 2 level).
>>>>
>>>> Signed-off-by: Eric Auger <eric.auger@...hat.com>
>>>> Signed-off-by: Shameer Kolothum
>> <shameerali.kolothum.thodi@...wei.com>
>>>> ---
>>>>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 13 ++++++++-----
>>>>   1 file changed, 8 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>>> b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>>> index 332d31c0680f..ab74a0289893 100644
>>>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>>> @@ -3038,14 +3038,17 @@ static int
>> arm_smmu_attach_pasid_table(struct
>>>> iommu_domain *domain,
>>>>           if (smmu_domain->s1_cfg.set)
>>>>               goto out;
>>>>   -        /*
>>>> -         * we currently support a single CD so s1fmt and s1dss
>>>> -         * fields are also ignored
>>>> -         */
>>>> -        if (cfg->pasid_bits)
>>>> +        list_for_each_entry(master, &smmu_domain->devices,
>>>> domain_head) {
>>>> +            if (cfg->pasid_bits > master->ssid_bits)
>>>> +                goto out;
>>>> +        }
>>>> +        if (cfg->vendor_data.smmuv3.s1fmt ==
>>>> STRTAB_STE_0_S1FMT_64K_L2 &&
>>>> +                !(smmu->features &
>> ARM_SMMU_FEAT_2_LVL_CDTAB))
>>>>               goto out;
>>>>             smmu_domain->s1_cfg.cdcfg.cdtab_dma = cfg->base_ptr;
>>>> +        smmu_domain->s1_cfg.s1cdmax = cfg->pasid_bits;
>>>> +        smmu_domain->s1_cfg.s1fmt =
>> cfg->vendor_data.smmuv3.s1fmt;
>>>
>>> And what about the SIDSS field?
>>>
>> I added this patch upon Shameer's request, to be more vSVA friendly.
>> Hower this series does not really target multiple CD support. At the
>> moment the driver only supports STRTAB_STE_1_S1DSS_SSID0 (0x2) I think.
>> At this moment maybe I can only check the s1dss field is 0x2. Or simply
>> removes this patch?
>>
>> Thoughts?
> 
> Right. This was useful for vSVA tests. But yes, to properly support multiple CDs
> we need to pass the S1DSS from Qemu. And that requires further changes.
> So I think it's better to remove this patch and reject S1CDMAX != 0 cases.
OK I will remove it

Thanks

Eric
> 
> Thanks,
> Shameer
>    
>>
>> Eric
>