On Mon, 2022-06-27 at 14:53 -0700, isaku.yamahata@xxxxxxxxx wrote: > From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > > TDX will use a different shadow PTE entry value for MMIO from VMX. Add > members to kvm_arch and track value for MMIO per-VM instead of global > variables. By using the per-VM EPT entry value for MMIO, the existing VMX > logic is kept working. > > In the case of VMX VM case, the EPT entry for MMIO is non-present PTE > (present bit cleared) without backing guest physical address (on EPT > violation, KVM searches backing guest memory and it finds there is no > backing guest page.) or the value to trigger EPT misconfiguration. Once > MMIO is triggered on the EPT entry, the EPT entry is updated to trigger EPT > misconfiguration for the future MMIO on the same GPA. It allows KVM to > understand the memory access is for MMIO without searching backing guest > pages.). And then KVM parses guest instruction to figure out > address/value/width for MMIO. > > In the case of the guest TD, the guest memory is protected so that VMM > can't parse guest instruction to understand the value and access width for > MMIO. Instead, VMM sets up (Shared) EPT to trigger #VE by clearing > the VE-suppress bit. When the guest TD issues MMIO, #VE is injected. Guest VE > handler converts MMIO access into MMIO hypercall to pass > address/value/width for MMIO to VMM. (or directly paravirtualize MMIO into > hypercall.) Then VMM can handle the MMIO hypercall without parsing guest > instructions. This is an infrastructural patch which enables per-VM MMIO caching. Why not putting this patch first so you don't need to do below changes (which are introduced by your previous patches)? [...] > > - if (!is_shadow_present_pte(spte) || is_mmio_spte(spte)) > + if (!is_shadow_present_pte(spte) || > + is_mmio_spte(vcpu->kvm, spte)) > break; > > [...] > @@ -1032,7 +1032,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) > gfn_t gfn; > > if (!is_shadow_present_pte(sp->spt[i]) && > - !is_mmio_spte(sp->spt[i])) > + !is_mmio_spte(vcpu->kvm, sp->spt[i])) > continue;
