Re: [PATCH 6/6] iommu: Make set_dev_pasid op support domain replacement

Yi Liu
2024-07-15T08:33:27Z

On 2024/7/15 16:02, Tian, Kevin wrote:
>> From: Liu, Yi L <yi.l.liu@intel.com>
>> Sent: Friday, June 28, 2024 4:56 PM
>>
>> The iommu core is going to support domain replacement for pasid, it needs
>> to make the set_dev_pasid op support replacing domain and keep the old
>> domain config in the failure case.
>>
>> Currently only the Intel iommu driver supports the latest set_dev_pasid
>> op definition. ARM and AMD iommu driver do not support domain
>> replacement
>> for pasid yet, both drivers would fail the set_dev_pasid op to keep the
>> old config if the input @old is non-NULL.
>
> why splitting this from patch01?

The major reason is we already have multiple set_dev_pasid callbacks. It's
better to make the existing callbacks suit the new definition before
claiming it. Although this is not quite true for ARM and AMD since their
set_dev_pasid() callback would fail replacement attempts. But it looks
like there is no pasid domain replacement usage on AMD and ARM due to arch
difference.

>>
>> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
>> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
>> ---
>> drivers/iommu/amd/pasid.c | 3 +++
>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 3 +++
>> include/linux/iommu.h | 3 ++-
>> 3 files changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/amd/pasid.c b/drivers/iommu/amd/pasid.c
>> index 77bf5f5f947a..30e27bda3fac 100644
>> --- a/drivers/iommu/amd/pasid.c
>> +++ b/drivers/iommu/amd/pasid.c
>> @@ -109,6 +109,9 @@ int iommu_sva_set_dev_pasid(struct iommu_domain
>> *domain,
>> unsigned long flags;
>> int ret = -EINVAL;
>>
>> + if (old)
>> + return -EOPNOTSUPP;
>> +
>> /* PASID zero is used for requests from the I/O device without PASID
>> */
>> if (!is_pasid_valid(dev_data, pasid))
>> return ret;
>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
>> b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
>> index c058949749cb..a1e411c71efa 100644
>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
>> @@ -637,6 +637,9 @@ static int arm_smmu_sva_set_dev_pasid(struct
>> iommu_domain *domain,
>> int ret = 0;
>> struct mm_struct *mm = domain->mm;
>>
>> + if (old)
>> + return -EOPNOTSUPP;
>> +
>> if (mm_get_enqcmd_pasid(mm) != id)
>> return -EINVAL;
>>
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index a33f53aab61b..3259f77ff2e3 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -607,7 +607,8 @@ struct iommu_ops {
>> * * EBUSY - device is attached to a domain and cannot be changed
>> * * ENODEV - device specific errors, not able to be attached
>> * * <others> - treated as ENODEV by the caller. Use is discouraged
>> - * @set_dev_pasid: set an iommu domain to a pasid of device
>> + * @set_dev_pasid: set or replace an iommu domain to a pasid of device.
>> The pasid of
>> + * the device should be left in the old config in error case.
>> * @map_pages: map a physically contiguous set of pages of the same size
>> to
>> * an iommu domain.
>> * @unmap_pages: unmap a number of pages of the same size from an
>> iommu domain
>> --
>> 2.34.1
>

--
Regards,
Yi Liu