Re: [PATCH 04/11] iommu/vt-d: Retire struct intel_svm_dev

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

On 2024/1/16 9:11, Tina Zhang wrote:
> The struct dev_pasid_info is used by IOMMU domain to keep pasid info of
> attached device. For sva domain, there is another structure which keeps
> info of attached device, named intel_svm_dev. Instead of using two structs
> for the same purpose, the struct dev_pasid_info can work for both sva
> domain and IOMMU domain. As a result, struct intel_svm_dev gets retired.
> 
> The rcu/did/sid/qdep fields of struct intel_svm_dev are moved from struct
> intel_svm_dev into struct dev_pasid_info. Besides, the names of functions
> which are related to struct intel_svm_dev get changed to dev_pasid_info.
> 
> Signed-off-by: Tina Zhang<tina.zhang@intel.com>
> ---
>   drivers/iommu/intel/iommu.h |  11 +---
>   drivers/iommu/intel/svm.c   | 110 ++++++++++++++++++------------------
>   2 files changed, 57 insertions(+), 64 deletions(-)

I like the direction that this patch is taking. I agree that
intel_svm_dev should be replaced with dev_pasid_info. However, since
dev_pasid_info is protected by domain->lock and intel_svm_dev is
protected by RCU, I recommend splitting this change into two patches:

- The first patch would modify the code to use domain->lock to protect
   intel_svm_dev.
- The second patch would then perform the actual replacement of
   intel_svm_dev with dev_pasid_info.

Best regards,
baolu