Re: [PATCH v6 05/10] iommufd: Derive iommufd_hwpt_paging from iommufd_hw_pagetable

[Jason Gunthorpe]

On Tue, Oct 24, 2023 at 08:06:04AM -0700, Yi Liu wrote:

>  static int iommufd_group_do_replace_paging(struct iommufd_group *igroup,
> -                                        struct iommufd_hw_pagetable *hwpt)
> +                                        struct iommufd_hwpt_paging 
> *hwpt_paging)
>  {
>       struct iommufd_hw_pagetable *old_hwpt = igroup->hwpt;
>       struct iommufd_device *cur;
> @@ -441,22 +447,23 @@ static int iommufd_group_do_replace_paging(struct 
> iommufd_group *igroup,
>  
>       lockdep_assert_held(&igroup->lock);
>  
> -     if (hwpt_is_paging(old_hwpt) && hwpt->ioas != old_hwpt->ioas) {
> +     if (hwpt_is_paging(old_hwpt) &&
> +         hwpt_paging->ioas != to_hwpt_paging(old_hwpt)->ioas) {
>               list_for_each_entry(cur, &igroup->device_list, group_item) {
>                       rc = iopt_table_enforce_dev_resv_regions(
> -                             &hwpt->ioas->iopt, cur->dev, NULL);
> +                             &hwpt_paging->ioas->iopt, cur->dev, NULL);
>                       if (rc)
>                               goto err_unresv;
>               }
>       }
>  
> -     rc = iommufd_group_setup_msi(igroup, hwpt);
> +     rc = iommufd_group_setup_msi(igroup, hwpt_paging);
>       if (rc)
>               goto err_unresv;
>       return 0;
>  
>  err_unresv:
> -     iommufd_group_remove_reserved_iova(igroup, hwpt);
> +     iommufd_group_remove_reserved_iova(igroup, hwpt_paging);
>       return rc;
>  }
>  
> @@ -482,7 +489,8 @@ iommufd_device_do_replace(struct iommufd_device *idev,
>       }
>  
>       if (hwpt_is_paging(hwpt)) {
> -             rc = iommufd_group_do_replace_paging(igroup, hwpt);
> +             rc = iommufd_group_do_replace_paging(igroup,
> +                                                  to_hwpt_paging(hwpt));
>               if (rc)
>                       goto err_unlock;
>       }
> @@ -493,8 +501,10 @@ iommufd_device_do_replace(struct iommufd_device *idev,
>  
>       old_hwpt = igroup->hwpt;
>       if (hwpt_is_paging(old_hwpt) &&
> -         (!hwpt_is_paging(hwpt) || hwpt->ioas != old_hwpt->ioas))
> -             iommufd_group_remove_reserved_iova(igroup, old_hwpt);
> +         (!hwpt_is_paging(hwpt) ||
> +          to_hwpt_paging(hwpt)->ioas != to_hwpt_paging(old_hwpt)->ioas))
> +             iommufd_group_remove_reserved_iova(igroup,
> +                                                to_hwpt_paging(old_hwpt));
>  
>       igroup->hwpt = hwpt;
>  
> @@ -513,7 +523,8 @@ iommufd_device_do_replace(struct iommufd_device *idev,
>       return old_hwpt;
>  err_unresv:
>       if (hwpt_is_paging(hwpt))
> -             iommufd_group_remove_reserved_iova(igroup, hwpt);
> +             iommufd_group_remove_reserved_iova(igroup,
> +                                                to_hwpt_paging(old_hwpt));

This gets a compiler warning:

../drivers/iommu/iommufd/device.c:527:25: warning: variable 'old_hwpt' is 
uninitialized when used here [-Wuninitialized]
                                                   to_hwpt_paging(old_hwpt));
                                                                  ^~~~~~~~
../drivers/iommu/iommufd/device.c:475:39: note: initialize the variable 
'old_hwpt' to silence this warning
        struct iommufd_hw_pagetable *old_hwpt;
                                             ^
                                              = NULL

I fixed it with:

--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -488,6 +488,7 @@ iommufd_device_do_replace(struct iommufd_device *idev,
                return NULL;
        }
 
+       old_hwpt = igroup->hwpt;
        if (hwpt_is_paging(hwpt)) {
                rc = iommufd_group_do_replace_paging(igroup,
                                                     to_hwpt_paging(hwpt));
@@ -499,7 +500,6 @@ iommufd_device_do_replace(struct iommufd_device *idev,
        if (rc)
                goto err_unresv;
 
-       old_hwpt = igroup->hwpt;
        if (hwpt_is_paging(old_hwpt) &&
            (!hwpt_is_paging(hwpt) ||
             to_hwpt_paging(hwpt)->ioas != to_hwpt_paging(old_hwpt)->ioas))

Jason