Re: [PATCH v13 3/8] iommu/vt-d: Add nested translation helper function

[Christoph Hellwig]

> +	 * 1. CPU vs. IOMMU
> +	 * 2. Guest vs. Host.
> +	 */
> +	switch (addr_width) {
> +#ifdef CONFIG_X86
> +	case ADDR_WIDTH_5LEVEL:
> +		if (cpu_feature_enabled(X86_FEATURE_LA57) &&
> +		    cap_5lp_support(iommu->cap)) {
> +			pasid_set_flpm(pte, 1);
> +		} else {
> +			dev_err_ratelimited(dev, "5-level paging not supported\n");
> +			return -EINVAL;
> +		}
> +		break;

The normal style would be to handle the early error return first:

		if (!cpu_feature_enabled(X86_FEATURE_LA57) ||
		    !cap_5lp_support(iommu->cap)) {
			dev_err_ratelimited(dev,
				"5-level paging not supported\n");
			return -EINVAL;
		}

		pasid_set_flpm(pte, 1);
		break;