Messages in this thread |  | | Subject | Re: [PATCH v8 02/10] iommu/vt-d: Add nested translation helper function | From | Lu Baolu <> | Date | Fri, 10 Jan 2020 09:15:45 +0800 |
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Hi Jacob,
On 1/10/20 2:39 AM, Jacob Pan wrote: > On Wed, 18 Dec 2019 10:41:53 +0800 > Lu Baolu <baolu.lu@linux.intel.com> wrote: > >> Hi again, >> >> On 12/17/19 3:24 AM, Jacob Pan wrote: >>> +/** >>> + * intel_pasid_setup_nested() - Set up PASID entry for nested >>> translation >>> + * which is used for vSVA. The first level page tables are used for >>> + * GVA-GPA or GIOVA-GPA translation in the guest, second level >>> page tables >>> + * are used for GPA-HPA translation. >>> + * >>> + * @iommu: Iommu which the device belong to >>> + * @dev: Device to be set up for translation >>> + * @gpgd: FLPTPTR: First Level Page translation pointer in >>> GPA >>> + * @pasid: PASID to be programmed in the device PASID table >>> + * @pasid_data: Additional PASID info from the guest bind request >>> + * @domain: Domain info for setting up second level page tables >>> + * @addr_width: Address width of the first level (guest) >>> + */ >>> +int intel_pasid_setup_nested(struct intel_iommu *iommu, >>> + struct device *dev, pgd_t *gpgd, >>> + int pasid, struct >>> iommu_gpasid_bind_data_vtd *pasid_data, >>> + struct dmar_domain *domain, >>> + int addr_width) >>> +{ >>> + struct pasid_entry *pte; >>> + struct dma_pte *pgd; >>> + u64 pgd_val; >>> + int agaw; >>> + u16 did; >>> + >>> + if (!ecap_nest(iommu->ecap)) { >>> + pr_err("IOMMU: %s: No nested translation >>> support\n", >>> + iommu->name); >>> + return -EINVAL; >>> + } >>> + >>> + pte = intel_pasid_get_entry(dev, pasid); >>> + if (WARN_ON(!pte)) >>> + return -EINVAL; >>> + >>> + pasid_clear_entry(pte); >> >> In some cases, e.g. nested mode for GIOVA-HPA, the PASID entry might >> have already been setup for second level translation. (This could be >> checked with the Present bit.) Hence, it's safe to flush caches here. >> >> Or, maybe intel_pasid_tear_down_entry() is more suitable? >> > We don't allow binding the same device-PASID twice, so if the PASID > entry was used for GIOVA/RID2PASID, it should unbind first, and > teardown flush included, right? >
Fair enough. Can you please add this as a comment to this function? So that the caller of this interface can know this. Or add a check in this function which returns error if the pasid entry has already been bond.
Best regards, baolu
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