On Fri, 10 Jan 2020 09:15:45 +0800 Lu Baolu <[email protected]> wrote:
> Hi Jacob, > > On 1/10/20 2:39 AM, Jacob Pan wrote: > > On Wed, 18 Dec 2019 10:41:53 +0800 > > Lu Baolu <[email protected]> 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. > Sounds good, i will do both comment and check as this: /* * Caller must ensure PASID entry is not in use, i.e. not bind the * same PASID to the same device twice. */ if (pasid_pte_is_present(pte)) return -EBUSY; We already have the check in the current caller. Thanks, > Best regards, > baolu [Jacob Pan] _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
