linux-kernel - Re: [PATCH v14 05/13] iommu/smmuv3: Implement attach/detach_pasid

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Date:   Fri, 19 Mar 2021 14:15:48 +0100
From:   Auger Eric <eric.auger@...hat.com>
To:     Keqian Zhu <zhukeqian1@...wei.com>, 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
Cc:     jacob.jun.pan@...ux.intel.com, yi.l.liu@...el.com,
        wangxingang5@...wei.com, jiangkunkun@...wei.com,
        jean-philippe@...aro.org, zhangfei.gao@...aro.org,
        zhangfei.gao@...il.com, vivek.gautam@....com,
        shameerali.kolothum.thodi@...wei.com, yuzenghui@...wei.com,
        nicoleotsuka@...il.com, lushenming@...wei.com, vsethi@...dia.com
Subject: Re: [PATCH v14 05/13] iommu/smmuv3: Implement
 attach/detach_pasid_table

Hi Keqian,

On 3/2/21 9:35 AM, Keqian Zhu wrote:
> Hi Eric,
> 
> On 2021/2/24 4:56, Eric Auger wrote:
>> On attach_pasid_table() we program STE S1 related info set
>> by the guest into the actual physical STEs. At minimum
>> we need to program the context descriptor GPA and compute
>> whether the stage1 is translated/bypassed or aborted.
>>
>> On detach, the stage 1 config is unset and the abort flag is
>> unset.
>>
>> Signed-off-by: Eric Auger <eric.auger@...hat.com>
>>
> [...]
> 
>> +
>> +		/*
>> +		 * we currently support a single CD so s1fmt and s1dss
>> +		 * fields are also ignored
>> +		 */
>> +		if (cfg->pasid_bits)
>> +			goto out;
>> +
>> +		smmu_domain->s1_cfg.cdcfg.cdtab_dma = cfg->base_ptr;
> only the "cdtab_dma" field of "cdcfg" is set, we are not able to locate a specific cd using arm_smmu_get_cd_ptr().
> 
> Maybe we'd better use a specialized function to fill other fields of "cdcfg" or add a sanity check in arm_smmu_get_cd_ptr()
> to prevent calling it under nested mode?
> 
> As now we just call arm_smmu_get_cd_ptr() during finalise_s1(), no problem found. Just a suggestion ;-)

forgive me for the delay. yes I can indeed make sure that code is not
called in nested mode. Please could you detail why you would need to
call arm_smmu_get_cd_ptr()?

Thanks

Eric
> 
> Thanks,
> Keqian
> 
> 
>> +		smmu_domain->s1_cfg.set = true;
>> +		smmu_domain->abort = false;
>> +		break;
>> +	default:
>> +		goto out;
>> +	}
>> +	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
>> +	list_for_each_entry(master, &smmu_domain->devices, domain_head)
>> +		arm_smmu_install_ste_for_dev(master);
>> +	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
>> +	ret = 0;
>> +out:
>> +	mutex_unlock(&smmu_domain->init_mutex);
>> +	return ret;
>> +}
>> +
>> +static void arm_smmu_detach_pasid_table(struct iommu_domain *domain)
>> +{
>> +	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>> +	struct arm_smmu_master *master;
>> +	unsigned long flags;
>> +
>> +	mutex_lock(&smmu_domain->init_mutex);
>> +
>> +	if (smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
>> +		goto unlock;
>> +
>> +	smmu_domain->s1_cfg.set = false;
>> +	smmu_domain->abort = false;
>> +
>> +	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
>> +	list_for_each_entry(master, &smmu_domain->devices, domain_head)
>> +		arm_smmu_install_ste_for_dev(master);
>> +	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
>> +
>> +unlock:
>> +	mutex_unlock(&smmu_domain->init_mutex);
>> +}
>> +
>>  static bool arm_smmu_dev_has_feature(struct device *dev,
>>  				     enum iommu_dev_features feat)
>>  {
>> @@ -2939,6 +3026,8 @@ static struct iommu_ops arm_smmu_ops = {
>>  	.of_xlate		= arm_smmu_of_xlate,
>>  	.get_resv_regions	= arm_smmu_get_resv_regions,
>>  	.put_resv_regions	= generic_iommu_put_resv_regions,
>> +	.attach_pasid_table	= arm_smmu_attach_pasid_table,
>> +	.detach_pasid_table	= arm_smmu_detach_pasid_table,
>>  	.dev_has_feat		= arm_smmu_dev_has_feature,
>>  	.dev_feat_enabled	= arm_smmu_dev_feature_enabled,
>>  	.dev_enable_feat	= arm_smmu_dev_enable_feature,
>>
>