Re: [PATCH v3 13/16] powerpc/pseries/iommu: Don't use dma_iommu_ops on secure guests

[Christoph Hellwig]

On Tue, Aug 06, 2019 at 02:22:34AM -0300, Thiago Jung Bauermann wrote:
> @@ -1318,7 +1319,10 @@ void iommu_init_early_pSeries(void)
>  	of_reconfig_notifier_register(&iommu_reconfig_nb);
>  	register_memory_notifier(&iommu_mem_nb);
>  
> -	set_pci_dma_ops(&dma_iommu_ops);
> +	if (is_secure_guest())
> +		set_pci_dma_ops(NULL);
> +	else
> +		set_pci_dma_ops(&dma_iommu_ops);

Shoudn't:

	if (!is_secure_guest())
		set_pci_dma_ops(&dma_iommu_ops);

be enough here, given that NULL is the default?

Also either way I think this conditional needs a comment explaining
why it is there.