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

[Yi Liu <yi.l.liu@intel.com>]

On 2024/3/27 21:05, Jason Gunthorpe wrote:
> On Wed, Mar 27, 2024 at 05:54:33AM -0700, 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 unnecessary remove_dev_pasid() calls on the
>> devices that have not changed in the __iommu_set_group_pasid() call. this
>> results in unnecessary warnings by the underlying iommu drivers. Like the
>> Intel iommu driver, it would warn when there is no pasid attachment to
>> destroy in the remove_dev_pasid() callback.
>>
>> The ideal way is to handle the error within __iommu_set_group_pasid(). This
>> not only makes __iommu_set_group_pasid() self-contained, but also avoids
>> unnecessary warnings.
>>
>> Fixes: 16603704559c7a68 ("iommu: Add attach/detach_dev_pasid iommu interfaces")
>> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
>> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
>> ---
>>   drivers/iommu/iommu.c | 20 ++++++++++++++------
>>   1 file changed, 14 insertions(+), 6 deletions(-)
> 
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> 
> This will need revising when we get to PASID replace, but good enough
> for now

yes, the rollback part would be revised a bit when coming to support
PASID domain replacement. Already in the pending list, will send it
out soon. :)

-- 
Regards,
Yi Liu