linux-kernel - Re: [PATCH v13 06/15] iommu/smmuv3: Implement attach/detach_pasid

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Date:   Thu, 11 Feb 2021 18:35:22 +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,
        joro@...tes.org, maz@...nel.org, robin.murphy@....com,
        alex.williamson@...hat.com
Cc:     jean-philippe@...aro.org, jacob.jun.pan@...ux.intel.com,
        nicoleotsuka@...il.com, vivek.gautam@....com, yi.l.liu@...el.com,
        zhangfei.gao@...aro.org
Subject: Re: [PATCH v13 06/15] iommu/smmuv3: Implement
 attach/detach_pasid_table

Hi Keqian,

On 2/2/21 9:03 AM, Keqian Zhu wrote:
> Hi Eric,
> 
> On 2020/11/18 19:21, 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.
>>
>> Signed-off-by: Eric Auger <eric.auger@...hat.com>
>>
>> ---
>> v7 -> v8:
>> - remove smmu->features check, now done on domain finalize
>>
>> v6 -> v7:
>> - check versions and comment the fact we don't need to take
>>   into account s1dss and s1fmt
>> v3 -> v4:
>> - adapt to changes in iommu_pasid_table_config
>> - different programming convention at s1_cfg/s2_cfg/ste.abort
>>
>> v2 -> v3:
>> - callback now is named set_pasid_table and struct fields
>>   are laid out differently.
>>
>> v1 -> v2:
>> - invalidate the STE before changing them
>> - hold init_mutex
>> - handle new fields
>> ---
>>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 89 +++++++++++++++++++++
>>  1 file changed, 89 insertions(+)
>>
>> 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 412ea1bafa50..805acdc18a3a 100644
>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> @@ -2661,6 +2661,93 @@ static void arm_smmu_get_resv_regions(struct device *dev,
>>  	iommu_dma_get_resv_regions(dev, head);
>>  }
>>  
>> +static int arm_smmu_attach_pasid_table(struct iommu_domain *domain,
>> +				       struct iommu_pasid_table_config *cfg)
>> +{
>> +	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>> +	struct arm_smmu_master *master;
>> +	struct arm_smmu_device *smmu;
>> +	unsigned long flags;
>> +	int ret = -EINVAL;
>> +
>> +	if (cfg->format != IOMMU_PASID_FORMAT_SMMUV3)
>> +		return -EINVAL;
>> +
>> +	if (cfg->version != PASID_TABLE_CFG_VERSION_1 ||
>> +	    cfg->vendor_data.smmuv3.version != PASID_TABLE_SMMUV3_CFG_VERSION_1)
>> +		return -EINVAL;
>> +
>> +	mutex_lock(&smmu_domain->init_mutex);
>> +
>> +	smmu = smmu_domain->smmu;
>> +
>> +	if (!smmu)
>> +		goto out;
>> +
>> +	if (smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
>> +		goto out;
>> +
>> +	switch (cfg->config) {
>> +	case IOMMU_PASID_CONFIG_ABORT:
>> +		smmu_domain->s1_cfg.set = false;
>> +		smmu_domain->abort = true;
>> +		break;
>> +	case IOMMU_PASID_CONFIG_BYPASS:
>> +		smmu_domain->s1_cfg.set = false;
>> +		smmu_domain->abort = false;
> I didn't test it, but it seems that this will cause BUG() in arm_smmu_write_strtab_ent().
> At the line "BUG_ON(ste_live && !nested);". Maybe I miss something?

No you are fully correct. Shammeer hit the BUG_ON() when booting the
guest with iommu.passthrough = 1. So I removed the BUG_ON(). The legacy
BUG_ON(ste_live) still is there under the form of BUG_ON(s1_live).

Thanks!

Eric


> 
>> +		break;
>> +	case IOMMU_PASID_CONFIG_TRANSLATE:
>> +		/* we do not support S1 <-> S1 transitions */
>> +		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)
>> +			goto out;
>> +
>> +		smmu_domain->s1_cfg.cdcfg.cdtab_dma = cfg->base_ptr;
>> +		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;
>> +}
>> +
> [...]
> 
> Thanks,
> Keqian
>