Re: [PATCH 2/6] iommu/vt-d: Implement hw_info for iommu capability query

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

On 2023/2/13 11:09, Binbin Wu wrote:
> 
> On 2/9/2023 12:16 PM, Yi Liu wrote:
>> From: Lu Baolu <baolu.lu@linux.intel.com>
>>
>> To support nested translation in the userspace, it should check the
>> underlying hardware information for the capabilities.
>>
>> Add intel_iommu_hw_info() to report cap_reg and ecap_reg information.
>>
>> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
>> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
>> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
>> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
>> ---
>>   drivers/iommu/intel/iommu.c  | 19 +++++++++++++++++++
>>   drivers/iommu/intel/iommu.h  |  1 +
>>   include/uapi/linux/iommufd.h | 21 +++++++++++++++++++++
>>   3 files changed, 41 insertions(+)
>>
>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>> index 59df7e42fd53..929f600cc350 100644
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -4760,8 +4760,26 @@ static void intel_iommu_remove_dev_pasid(struct 
>> device *dev, ioasid_t pasid)
>>       intel_pasid_tear_down_entry(iommu, dev, pasid, false);
>>   }
>> +static void *intel_iommu_hw_info(struct device *dev, u32 *length)
>> +{
>> +    struct device_domain_info *info = dev_iommu_priv_get(dev);
>> +    struct intel_iommu *iommu = info->iommu;
>> +    struct iommu_device_info_vtd *vtd;
>> +
>> +    vtd = kzalloc(sizeof(*vtd), GFP_KERNEL);
>> +    if (!vtd)
>> +        return ERR_PTR(-ENOMEM);
>> +
>> +    vtd->cap_reg = iommu->cap;
>> +    vtd->ecap_reg = iommu->ecap;
>> +    *length = sizeof(*vtd);
>> +
>> +    return vtd;
>> +}
>> +
>>   const struct iommu_ops intel_iommu_ops = {
>>       .capable        = intel_iommu_capable,
>> +    .hw_info        = intel_iommu_hw_info,
>>       .domain_alloc        = intel_iommu_domain_alloc,
>>       .probe_device        = intel_iommu_probe_device,
>>       .probe_finalize        = intel_iommu_probe_finalize,
>> @@ -4774,6 +4792,7 @@ const struct iommu_ops intel_iommu_ops = {
>>       .def_domain_type    = device_def_domain_type,
>>       .remove_dev_pasid    = intel_iommu_remove_dev_pasid,
>>       .pgsize_bitmap        = SZ_4K,
>> +    .driver_type        = IOMMU_DEVICE_DATA_INTEL_VTD,
>>   #ifdef CONFIG_INTEL_IOMMU_SVM
>>       .page_response        = intel_svm_page_response,
>>   #endif
>> diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
>> index 06e61e474856..2e70265d4ceb 100644
>> --- a/drivers/iommu/intel/iommu.h
>> +++ b/drivers/iommu/intel/iommu.h
>> @@ -22,6 +22,7 @@
>>   #include <linux/ioasid.h>
>>   #include <linux/bitfield.h>
>>   #include <linux/xarray.h>
>> +#include <uapi/linux/iommufd.h>
>>   #include <asm/cacheflush.h>
>>   #include <asm/iommu.h>
>> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
>> index 2309edb55028..fda75c8450ee 100644
>> --- a/include/uapi/linux/iommufd.h
>> +++ b/include/uapi/linux/iommufd.h
>> @@ -347,7 +347,28 @@ struct iommu_vfio_ioas {
>>   /**
>>    * enum iommu_device_data_type - IOMMU hardware Data types
>> + * @IOMMU_DEVICE_DATA_INTEL_VTD: Intel VT-d iommu data type
>>    */
>>   enum iommu_device_data_type {
>> +    IOMMU_DEVICE_DATA_INTEL_VTD = 1,
>> +};
>> +
>> +/**
>> + * struct iommu_device_info_vtd - Intel VT-d device info
>> + *
>> + * @flags: Must be set to 0
> 
> Could you add more description about the usage of flags here?

This is a Reserved 0 fields for other coming features.

Best regards,
baolu