On Wed, Nov 10, 2021 at 2:45 PM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 11/10/21 23:30, Ben Gardon wrote: > > - WARN_ONCE(is_rsvd_spte(&vcpu->arch.mmu->shadow_zero_check, spte, level), > > + WARN_ONCE(is_rsvd_spte(shadow_zero_check, spte, level), > > "spte = 0x%llx, level = %d, rsvd bits = 0x%llx", spte, level, > > - get_rsvd_bits(&vcpu->arch.mmu->shadow_zero_check, spte, level)); > > + get_rsvd_bits(shadow_zero_check, spte, level)); > > Hmm, there is a deeper issue here, in that when using EPT/NPT (on either > the legacy aka shadow or the TDP MMU) large parts of vcpu->arch.mmu are > really the same for all vCPUs. The only thing that varies is those > parts that actually depend on the guest's paging mode---the extended > role, the reserved bits, etc. Those are needed by the emulator, but > don't really belong in vcpu->arch.mmu when EPT/NPT is in use. > > I wonder if there's room for splitting kvm_mmu in two parts, such as > kvm_mmu and kvm_guest_paging_context, and possibly change the walk_mmu > pointer into a pointer to kvm_guest_paging_context. This way the > EPT/NPT MMU (again either shadow or TDP) can be moved to kvm->arch. It > should simplify this series and also David's work on eager page splitting. > > I'm not asking you to do this, of course, but perhaps I can trigger > Sean's itch to refactor stuff. :) > > Paolo > I think that's a great idea. I'm frequently confused as to why the struct kvm_mmu is a per-vcpu construct as opposed to being VM-global. Moving part of the struct to be a member for struct kvm would also open the door to formalizing the MMU interface a little better and perhaps even reveal more MMU code that can be consolidated across architectures.
