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

Yi Liu
2023-09-25T06:35:46Z

On 2023/9/20 21:18, Jason Gunthorpe wrote:
> On Wed, Sep 20, 2023 at 01:10:04PM +0000, Liu, Yi L wrote:
>>> From: Jason Gunthorpe <jgg@nvidia.com>
>>> Sent: Wednesday, September 20, 2023 9:05 PM
>>>
>>> On Wed, Sep 20, 2023 at 01:28:41PM +0800, Baolu Lu wrote:
>>>>>
>>>>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>>>>> index 5db283c17e0d..491bcde1ff96 100644
>>>>> --- a/drivers/iommu/intel/iommu.c
>>>>> +++ b/drivers/iommu/intel/iommu.c
>>>>> @@ -4074,6 +4074,25 @@ 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;
>>>>> +
>>>>> + iommu = device_to_iommu(dev, NULL, NULL);
>>>>> + if (!iommu)
>>>>> + return ERR_PTR(-ENODEV);
>>>>> +
>>>>> + if ((flags & IOMMU_HWPT_ALLOC_NEST_PARENT) && !ecap_nest(iommu-
>>>> ecap))
>>>>> + return ERR_PTR(-EOPNOTSUPP);
>>>
>>> There is a check missing for supported flags
>>>
>>> if (flags & (~IOMMU_HWPT_ALLOC_NEST_PARENT))
>>> return ERR_PTR(-EOPNOTSUPP);
>>
>> Well, the iommufd has such check. But I also noticed your another
>> reply to Weijiang. So your preference is to do the flags validation
>> in iommu driver instead of iommufd. Isn't it?
>
> The core code should check that only kernel known bits are set
>
> The driver code should check that only driver supported bits are set.
>
> Today there is only one bit so the checks are the same code.
>
> Tomorrow when we add a new bit the checks will not be the same

fair enough. I'll have the check in both core and iommu driver.

if (flags & (~IOMMU_HWPT_ALLOC_NEST_PARENT))
return ERR_PTR(-EOPNOTSUPP);

--
Regards,
Yi Liu