RE: [PATCH v4 04/12] iommu/vt-d: Add helper to setup pasid nested translation

[Tian, Kevin]

> From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> Sent: Monday, July 24, 2023 7:13 PM
>  }
> +
> +/**
> + * intel_pasid_setup_nested() - Set up PASID entry for nested translation.
> + * This could be used for nested translation based vIOMMU. e.g. guest IOVA

s/could be/is/

> + * and guest shared virtual address. In this case, the first level page
> + * tables are used for GVA/GIOVA-GPA translation in the guest, second level
> + * page tables are used for GPA-HPA translation.

let's be consistent on using stage-1/stage-2

btw the convention is to have 1-line summary, then the list of
parameters followed by detail explanation of the function.

> + *
> + * @iommu:      IOMMU which the device belong to
> + * @dev:        Device to be set up for translation
> + * @pasid:      PASID to be programmed in the device PASID table
> + * @domain:     User stage-1 domain nested on a s2 domain
> + */
> +int intel_pasid_setup_nested(struct intel_iommu *iommu, struct device
> *dev,
> +			     u32 pasid, struct dmar_domain *domain)
> +{
> +	struct iommu_hwpt_vtd_s1 *s1_cfg = &domain->s1_cfg;
> +	pgd_t *s1_gpgd = (pgd_t *)(uintptr_t)domain->s1_pgtbl;
> +	struct dmar_domain *s2_domain = domain->s2_domain;
> +	u16 did = domain_id_iommu(domain, iommu);
> +	struct dma_pte *pgd = s2_domain->pgd;
> +	struct pasid_entry *pte;
> +
> +	if (!ecap_nest(iommu->ecap)) {
> +		pr_err_ratelimited("%s: No nested translation support\n",
> +				   iommu->name);
> +		return -ENODEV;
> +	}

-EINVAL

> +
> +	if (s2_domain->agaw > iommu->agaw) {
> +		pr_err_ratelimited("Incompatible agaw %s\n", iommu-
> >name);
> +		return -EINVAL;
> +	}

there is a duplicated check in intel_nested_attach_dev().

> +
> +	pasid_set_slptr(pte, virt_to_phys(pgd));
> +	pasid_set_fault_enable(pte);
> +	pasid_set_domain_id(pte, did);
> +	pasid_set_address_width(pte, s2_domain->agaw);
> +	pasid_set_page_snoop(pte, !!ecap_smpwc(iommu->ecap));
> +	pasid_set_translation_type(pte, PASID_ENTRY_PGTT_NESTED);
> +	pasid_set_present(pte);
> +	spin_unlock(&iommu->lock);
> +

this lacks of handling of force_snooping