Re: [PATCH v3 15/15] iommu/amd: Add support for nested domain attach/detach

["Suthikulpanit, Suravee" <suravee.suthikulpanit@amd.com>]

On 10/10/2025 6:20 PM, Jason Gunthorpe wrote:
> On Thu, Oct 09, 2025 at 11:57:55PM +0000, Suravee Suthikulpanit wrote:
>> Introduce set_dte_nested() to program guest translation settings in
>> the host DTE when attaches the nested domain to a device.
>> .....
>>
>> +static int nested_attach_device(struct iommu_domain *dom, struct device *dev)
>> +{
>> +	struct iommu_dev_data *dev_data = dev_iommu_priv_get(dev);
>> +	struct amd_iommu *iommu = get_amd_iommu_from_dev_data(dev_data);
>> +	int ret = 0;
>> +
>> +	if (WARN_ON(dom->type != IOMMU_DOMAIN_NESTED))
>> +		return -EINVAL;
>> +
>> +	mutex_lock(&dev_data->mutex);
>> +
>> +	/* Update device table entry */
>> +	set_dte_nested(iommu, dom, dev_data);
>> +	amd_iommu_device_flush_dte(dev_data);
>> +	amd_iommu_completion_wait(iommu);
>> +
>> +	mutex_unlock(&dev_data->mutex);
> 
> Where does the code record the ndom->id to push invalidates when the
> S2 is changed? Seems like an important thing to be missing!
> 
> Shouldn't all this attach related stuff be in here too??
> 
>          ret = pdom_attach_iommu(iommu, domain);
>          dev_data->domain = domain;
> 
>          spin_lock_irqsave(&domain->lock, flags);
>          list_add(&dev_data->list, &domain->dev_list);
>          spin_unlock_irqrestore(&domain->lock, flags);
> 
> At a bare minimum if the series is going to stop here then it must
> also do correct invalidation for any S2 changes.
> 
> Given that, I'd suggest to also fix the domain id's with the xarray so
> you don't have to redo the invalidation logic.
> 
> Jason

I am reworking this series to include S2 flushing, and will be sending 
out v4.

Thanks,
Suravee