Re: [PATCH v3 1/2] iommu/amd: Remove PT_FEAT_DYNAMIC_TOP from PT_FORCE_ENABLED_FEATURES

[Vasant Hegde <vasant.hegde@amd.com>]

+ Jason

On 3/9/2026 7:35 PM, Ankit Soni wrote:
> Dynamic top is used to grow the page table levels. However, if the VA
> size is small and the initial page table level already covers the entire
> address space, table growth is not required. In that case, the generic
> page table framework clears PT_FEAT_DYNAMIC_TOP, which in turn causes
> error -EOPNOTSUPP and leads to domain initialization failure.
> 
> Remove PT_FEAT_DYNAMIC_TOP from PT_FORCE_ENABLED_FEATURES, since during
> domain allocation AMD IOMMU driver explicitly sets PT_FEAT_DYNAMIC_TOP
> via cfg.common.features, this keeps normal runtime behavior unchanged.
> 

Fixes: 879ced2bab1 ("iommupt: Add the AMD IOMMU v1 page table format")

> Signed-off-by: Ankit Soni <Ankit.Soni@amd.com>

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>


-Vasant

> ---
>  drivers/iommu/generic_pt/fmt/iommu_amdv1.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/generic_pt/fmt/iommu_amdv1.c b/drivers/iommu/generic_pt/fmt/iommu_amdv1.c
> index 72a2337d0c55..61e025a85e6a 100644
> --- a/drivers/iommu/generic_pt/fmt/iommu_amdv1.c
> +++ b/drivers/iommu/generic_pt/fmt/iommu_amdv1.c
> @@ -9,7 +9,7 @@
>  	 BIT(PT_FEAT_AMDV1_ENCRYPT_TABLES) |                           \
>  	 BIT(PT_FEAT_AMDV1_FORCE_COHERENCE))
>  #define PT_FORCE_ENABLED_FEATURES                                       \
> -	(BIT(PT_FEAT_DYNAMIC_TOP) | BIT(PT_FEAT_AMDV1_ENCRYPT_TABLES) | \
> +	(BIT(PT_FEAT_AMDV1_ENCRYPT_TABLES) |				\
>  	 BIT(PT_FEAT_AMDV1_FORCE_COHERENCE))
>  
>  #include "iommu_template.h"