On 2023/10/20 15:53, Tian, Kevin wrote:
From: Joao Martins<joao.m.martins@xxxxxxxxxx> Sent: Thursday, October 19, 2023 4:27 AM + + if (!IS_ERR(domain) && enforce_dirty) { + if (to_dmar_domain(domain)->use_first_level) { + iommu_domain_free(domain); + return ERR_PTR(-EOPNOTSUPP); + } + domain->dirty_ops = &intel_dirty_ops; + }I don't understand why we should check use_first_level here. It's a dead condition as alloc_user() only uses 2nd level. Later when nested is introduced then we explicitly disallow enforce_dirty on a nested user domain.
This is to restrict dirty tracking to the second level page table *explicitly*. If we have a need to enable dirty tracking on the first level in the future, we can remove this check. Best regards, baolu
