RE: [PATCH v2 1/4] iommu/vt-d: Block PASID attachment to nested domain with dirty tracking

[Duan, Zhenzhong]

>-----Original Message-----
>From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
>Subject: Re: [PATCH v2 1/4] iommu/vt-d: Block PASID attachment to nested
>domain with dirty tracking
>
>On 3/30/26 18:11, Zhenzhong Duan wrote:
>> Kernel lacks dirty tracking support on nested domain attached to PASID,
>> fails the attachment early if nesting parent domain is dirty tracking
>> configured, otherwise dirty pages would be lost.
>>
>> Cc: stable@xxxxxxxxxxxxxxx
>> Fixes: f35f22cc760e ("iommu/vt-d: Access/Dirty bit support for SS domains")
>> Suggested-by: Kevin Tian <kevin.tian@xxxxxxxxx>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxx>
>> ---
>>   drivers/iommu/intel/nested.c | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>
>Good catch. Just one nit. I think the below fix tag is more accurate. SS
>dirty was merged before PASID attachment. So this fix should be
>backported since the first PASID nested domain attachment.

Oh, I see, thanks for sharing the history.

>
>Fixes: 67f6f56b5912 ("iommu/vt-d: Add set_dev_pasid callback for nested
>domain")

I'll leave it to Baolu to decide if he want a respin or will pick this directly.

BRs,
Zhenzhong

>
>Reviewed-by: Yi Liu <yi.l.liu@xxxxxxxxx>
>
>> diff --git a/drivers/iommu/intel/nested.c b/drivers/iommu/intel/nested.c
>> index 2b979bec56ce..16c82ba47d30 100644
>> --- a/drivers/iommu/intel/nested.c
>> +++ b/drivers/iommu/intel/nested.c
>> @@ -148,6 +148,7 @@ static int intel_nested_set_dev_pasid(struct
>iommu_domain *domain,
>>   {
>>   	struct device_domain_info *info = dev_iommu_priv_get(dev);
>>   	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
>> +	struct iommu_domain *s2_domain = &dmar_domain->s2_domain-
>>domain;
>>   	struct intel_iommu *iommu = info->iommu;
>>   	struct dev_pasid_info *dev_pasid;
>>   	int ret;
>> @@ -155,10 +156,13 @@ static int intel_nested_set_dev_pasid(struct
>iommu_domain *domain,
>>   	if (!pasid_supported(iommu) || dev_is_real_dma_subdevice(dev))
>>   		return -EOPNOTSUPP;
>>
>> +	if (s2_domain->dirty_ops)
>> +		return -EINVAL;
>> +
>>   	if (context_copied(iommu, info->bus, info->devfn))
>>   		return -EBUSY;
>>
>> -	ret = paging_domain_compatible(&dmar_domain->s2_domain->domain,
>dev);
>> +	ret = paging_domain_compatible(s2_domain, dev);
>>   	if (ret)
>>   		return ret;
>>