Re: [PATCH v2 6/6] iommu/vt-d: Add domain_alloc_user op

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

On 10/11/23 12:43 AM, Jason Gunthorpe wrote:
> On Thu, Sep 28, 2023 at 12:15:28AM -0700, Yi Liu wrote:
>> This adds the domain_alloc_user op implementation. It supports allocating
>> domains to be used as parent under nested translation.
>>
>> Signed-off-by: Yi Liu<yi.l.liu@intel.com>
>> ---
>>   drivers/iommu/intel/iommu.c | 28 ++++++++++++++++++++++++++++
>>   1 file changed, 28 insertions(+)
>>
>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>> index 5db283c17e0d..017aed5813d8 100644
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -4074,6 +4074,33 @@ static struct iommu_domain *intel_iommu_domain_alloc(unsigned type)
>>   	return NULL;
>>   }
>>   
>> +static struct iommu_domain *
>> +intel_iommu_domain_alloc_user(struct device *dev, u32 flags)
>> +{
>> +	struct iommu_domain *domain;
>> +	struct intel_iommu *iommu;
>> +
>> +	if (flags & (~IOMMU_HWPT_ALLOC_NEST_PARENT))
>> +		return ERR_PTR(-EOPNOTSUPP);
>> +
>> +	iommu = device_to_iommu(dev, NULL, NULL);
>> +	if (!iommu)
>> +		return ERR_PTR(-ENODEV);
> Why isn't this just
> 
> 	struct device_domain_info *info = dev_iommu_priv_get(dev)
> 	struct intel_iommu *iommu = info->iommu
> 
> ???
> 
> Same question for almost all other calls to this function! The one in
> probe is reasonable, but I don't think it should be ever called again.
> 
> I'm going to leave this, but please make a series cleaning all the
> device_to_iommu() stuff next cycle..

Sure. I also have a plan to do this. device_to_iommu() is only needed in
the probe path. For runtime callbacks, we can just retrieve it from the
device's iommu private data.

Best regards,
baolu