Re: [PATCH v2 1/2] iommu: Undo pasid attachment only for the devices that have succeeded

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

On 3/28/24 8:29 PM, Yi Liu wrote:
> There is no error handling now in __iommu_set_group_pasid(), it relies on
> its caller to loop all the devices to undo the pasid attachment. This is
> not self-contained and has drawbacks. It would result in unnecessary
> remove_dev_pasid() calls on the devices that have not been attached to the
> new domain. But the remove_dev_pasid() callback would get the new domain
> from the group->pasid_array. So for such devices, the iommu driver won't
> find the attachment under the domain, hence unable to do cleanup. This may
> not be a real problem today. But it depends on the implementation of the
> underlying iommu driver. e.g. the intel iommu driver would warn for such
> devices. Such warnings are unnecessary.
> 
> To solve the above problem, it is necessary to handle the error within
> __iommu_set_group_pasid(). It only loops the devices that have attached
> to the new domain, and undo it.
> 
> Fixes: 16603704559c ("iommu: Add attach/detach_dev_pasid iommu interfaces")
> Suggested-by: Jason Gunthorpe<jgg@nvidia.com>
> Reviewed-by: Jason Gunthorpe<jgg@nvidia.com>
> Reviewed-by: Kevin Tian<kevin.tian@intel.com>
> Signed-off-by: Yi Liu<yi.l.liu@intel.com>

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu