On 7/23/22 03:23, Sean Christopherson wrote:
Patch 6 from Mingwei is the end goal of the series. KVM incorrectly assumes that the NX huge page mitigation is the only scenario where KVM will create a non-leaf page instead of a huge page. Precisely track (via kvm_mmu_page) if a non-huge page is being forced and use that info to avoid unnecessarily forcing smaller page sizes in disallowed_hugepage_adjust(). v2: Rebase, tweak a changelog accordingly. v1:https://lore.kernel.org/all/20220409003847.819686-1-seanjc@xxxxxxxxxx Mingwei Zhang (1): KVM: x86/mmu: explicitly check nx_hugepage in disallowed_hugepage_adjust() Sean Christopherson (5): KVM: x86/mmu: Tag disallowed NX huge pages even if they're not tracked KVM: x86/mmu: Properly account NX huge page workaround for nonpaging MMUs KVM: x86/mmu: Set disallowed_nx_huge_page in TDP MMU before setting SPTE KVM: x86/mmu: Track the number of TDP MMU pages, but not the actual pages KVM: x86/mmu: Add helper to convert SPTE value to its shadow page
Some of the benefits are cool, such as not having to track the pages for the TDP MMU, and patch 2 is a borderline bugfix, but there's quite a lot of new non-obvious complexity here.
So the obligatory question is: is it worth a hundred lines of new code? Paolo
