Re: [PATCH v4 06/12] iommu/vt-d: Set the nested domain to a device

[Baolu Lu <baolu.lu@linux.intel.com>]

On 2023/8/2 15:22, Tian, Kevin wrote:
>> From: Liu, Yi L <yi.l.liu@intel.com>
>> Sent: Monday, July 24, 2023 7:13 PM
>> +
>> +static int intel_nested_attach_dev(struct iommu_domain *domain,
>> +				   struct device *dev)
>> +{
>> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
>> +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
>> +	struct intel_iommu *iommu = info->iommu;
>> +	unsigned long flags;
>> +	int ret = 0;
>> +
>> +	if (info->domain)
>> +		device_block_translation(dev);
>> +
>> +	if (iommu->agaw < dmar_domain->s2_domain->agaw) {
>> +		dev_err_ratelimited(dev, "Adjusted guest address width not
>> compatible\n");
>> +		return -ENODEV;
>> +	}
> 
> this is the check duplicated with patch04.

Ack. No need for a check here.

> 
>> +
>> +	ret = domain_attach_iommu(dmar_domain, iommu);
>> +	if (ret) {
>> +		dev_err_ratelimited(dev, "Failed to attach domain to
>> iommu\n");
>> +		return ret;
>> +	}
>> +
> 
> [...]
> 
>> +	domain_update_iommu_cap(dmar_domain);
> 
> iommu_cap is already updated in domain_attach_iommu().

Ack. We will eventually remove this helper when every domain is
allocated for a specific device.

>>
>>   static const struct iommu_domain_ops intel_nested_domain_ops = {
>> +	.attach_dev		= intel_nested_attach_dev,
>>   	.free			= intel_nested_domain_free,
>> +	.enforce_cache_coherency = intel_iommu_enforce_cache_coherency,
> 
> this is not required. enforce_cache_coherency() will be called on parent
> hwpt when it's being created. patch04 should check parent's force_snooping
> to set pgsnp in the pasid entry.
> 
> As Jason explained it should be done only for kernel owned page table.

Ack and thanks!

Best regards,
baolu