Re: [PATCH 4/6] iommufd/hw_pagetable: Support allocating nested parent domain

Baolu Lu
2023-09-20T05:08:31Z

On 9/19/23 5:25 PM, Yi Liu wrote:
> This extends IOMMU_HWPT_ALLOC to allocate domains used as parent (stage-2)
> in nested translation.
>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
> drivers/iommu/iommufd/hw_pagetable.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
> index 5be7a31cbd9c..26a8a818ffa3 100644
> --- a/drivers/iommu/iommufd/hw_pagetable.c
> +++ b/drivers/iommu/iommufd/hw_pagetable.c
> @@ -83,6 +83,9 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
>
> lockdep_assert_held(&ioas->mutex);
>
> + if ((flags & IOMMU_HWPT_ALLOC_NEST_PARENT) && !ops->domain_alloc_user)
> + return ERR_PTR(-EOPNOTSUPP);
> +
> hwpt = iommufd_object_alloc(ictx, hwpt, IOMMUFD_OBJ_HW_PAGETABLE);
> if (IS_ERR(hwpt))
> return hwpt;
> @@ -154,7 +157,7 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
> struct iommufd_ioas *ioas;
> int rc;
>
> - if (cmd->flags || cmd->__reserved)
> + if (cmd->flags & ~IOMMU_HWPT_ALLOC_NEST_PARENT || cmd->__reserved)
> return -EOPNOTSUPP;

Need a parenthesis here, otherwise the compiler will interpret it as a
different condition.

if ((cmd->flags & ~IOMMU_HWPT_ALLOC_NEST_PARENT) || cmd->__reserved)
return -EOPNOTSUPP;

Best regards,
baolu