On 11/11/21 02:18, Sean Christopherson wrote:
But what would you actually move? Even shadow_zero_check barely squeaks by, e.g. if NX is ever used to for NPT, then maybe it stops being a per-VM setting.
Hmm, I think it would still be per-VM, just like 32-bit shadow page tables are always built for EFER.NXE=CR4.PAE=1. Anyway, the rough sketch is to have three structs: * struct kvm_mmu_kind has the function pointers and the state that is needed to operate on page tables * struct kvm_mmu has the function pointers and the state that is needed while the vCPU runs, including the role * struct kvm_paging_context has the stuff related to emulation; shadow page tables of course needs it but EPT/NPT do not (with either the old or the new MMU) So you'd have a "struct kvm_mmu_kind direct_mmu" in struct kvm_arch (for either legacy EPT/NPT or the new MMU), and struct kvm_mmu_kind shadow_mmu; struct kvm_mmu root_mmu; /* either TDP or shadow */ struct kvm_mmu tdp12_mmu; /* always shadow */ struct kvm_mmu *mmu; /* either &kvm->direct_mmu or &vcpu->shadow_mmu */ struct kvm_paging_context root_walk; /* maybe unified with walk01 below? dunno yet */ struct kvm_paging_context walk01; struct kvm_paging_context walk12; struct kvm_paging_context *walk; /* either &vcpu->root_walk or &vcpu->walk12 */ in struct kvm_vcpu_arch. struct kvm_mmu* has a pointer to struct kvm_mmu_kind*; however, if an spte.c function does not need the data in struct kvm_mmu_state*, it can take a struct kvm_mmu_kind* and it won't need a vCPU. Likewise the TDP MMU knows its kvm_mmu_kind is always in &kvm->direct_mmu so it can take a struct kvm* if the struct kvm_mmu_state* is not needed. The first part of the refactoring would be to kill the nested_mmu and walk_mmu, replacing them by &vcpu->walk12 and vcpu->walk respectively. The half-useless nested_mmu has always bothered me, I was going to play with it anyway because I want to remove the kvm_mmu_reset_context from CR0.WP writes, I'll see if I get something useful out of it. Paolo
