Tian, Kevin
2022-Jun-17 02:53 UTC
[PATCH v2 5/5] vfio/iommu_type1: Simplify group attachment
> From: Nicolin Chen <nicolinc at nvidia.com> > Sent: Friday, June 17, 2022 6:41 AM > > > ... > > > - if (resv_msi) { > > > + if (resv_msi && !domain->msi_cookie) { > > > ret = iommu_get_msi_cookie(domain->domain, > > > resv_msi_base); > > > if (ret && ret != -ENODEV) > > > goto out_detach; > > > + domain->msi_cookie = true; > > > } > > > > why not moving to alloc_attach_domain() then no need for the new > > domain field? It's required only when a new domain is allocated. > > When reusing an existing domain that doesn't have an msi_cookie, > we can do iommu_get_msi_cookie() if resv_msi is found. So it is > not limited to a new domain.Looks msi_cookie requirement is per platform (currently only for smmu. see arm_smmu_get_resv_regions()). If there is no mixed case then above check is not required. But let's hear whether Robin has a different thought here.> > > ... > > > - if (list_empty(&domain->group_list)) { > > > - if (list_is_singular(&iommu->domain_list)) { > > > - if (list_empty(&iommu- > > > >emulated_iommu_groups)) { > > > - WARN_ON(iommu->notifier.head); > > > - > > > vfio_iommu_unmap_unpin_all(iommu); > > > - } else { > > > - > > > vfio_iommu_unmap_unpin_reaccount(iommu); > > > - } > > > - } > > > - iommu_domain_free(domain->domain); > > > - list_del(&domain->next); > > > - kfree(domain); > > > - vfio_iommu_aper_expand(iommu, &iova_copy); > > > > Previously the aperture is adjusted when a domain is freed... > > > > > - vfio_update_pgsize_bitmap(iommu); > > > - } > > > - /* > > > - * Removal of a group without dirty tracking may allow > > > - * the iommu scope to be promoted. > > > - */ > > > - if (!group->pinned_page_dirty_scope) { > > > - iommu->num_non_pinned_groups--; > > > - if (iommu->dirty_page_tracking) > > > - vfio_iommu_populate_bitmap_full(iommu); > > > - } > > > + vfio_iommu_detach_destroy_domain(domain, iommu, > > > group); > > > kfree(group); > > > break; > > > } > > > > > > + vfio_iommu_aper_expand(iommu, &iova_copy); > > > > but now it's done for every group detach. The aperture is decided > > by domain geometry which is not affected by attached groups. > > Yea, I've noticed this part. Actually Jason did this change for > simplicity, and I think it'd be safe to do so?Perhaps detach_destroy() can return a Boolean to indicate whether a domain is destroyed.
Robin Murphy
2022-Jun-20 10:11 UTC
[PATCH v2 5/5] vfio/iommu_type1: Simplify group attachment
On 2022-06-17 03:53, Tian, Kevin wrote:>> From: Nicolin Chen <nicolinc at nvidia.com> >> Sent: Friday, June 17, 2022 6:41 AM >> >>> ... >>>> - if (resv_msi) { >>>> + if (resv_msi && !domain->msi_cookie) { >>>> ret = iommu_get_msi_cookie(domain->domain, >>>> resv_msi_base); >>>> if (ret && ret != -ENODEV) >>>> goto out_detach; >>>> + domain->msi_cookie = true; >>>> } >>> >>> why not moving to alloc_attach_domain() then no need for the new >>> domain field? It's required only when a new domain is allocated. >> >> When reusing an existing domain that doesn't have an msi_cookie, >> we can do iommu_get_msi_cookie() if resv_msi is found. So it is >> not limited to a new domain. > > Looks msi_cookie requirement is per platform (currently only > for smmu. see arm_smmu_get_resv_regions()). If there is > no mixed case then above check is not required. > > But let's hear whether Robin has a different thought here.Yes, the cookie should logically be tied to the lifetime of the domain itself. In the relevant context, "an existing domain that doesn't have an msi_cookie" should never exist. Thanks, Robin.