Re: [PATCH v13 20/35] KVM: x86/mmu: Handle page fault for private memory

[Xu Yilun]

> +static void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu,
> +                                           struct kvm_page_fault *fault)
> +{
> +     kvm_prepare_memory_fault_exit(vcpu, fault->gfn << PAGE_SHIFT,
> +                                   PAGE_SIZE, fault->write, fault->exec,
> +                                   fault->is_private);
> +}
> +
> +static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu,
> +                                struct kvm_page_fault *fault)
> +{
> +     int max_order, r;
> +
> +     if (!kvm_slot_can_be_private(fault->slot)) {
> +             kvm_mmu_prepare_memory_fault_exit(vcpu, fault);
> +             return -EFAULT;
> +     }
> +
> +     r = kvm_gmem_get_pfn(vcpu->kvm, fault->slot, fault->gfn, &fault->pfn,
> +                          &max_order);
> +     if (r) {
> +             kvm_mmu_prepare_memory_fault_exit(vcpu, fault);
> +             return r;

Why report KVM_EXIT_MEMORY_FAULT here? even with a ret != -EFAULT? This is
different from the decription where KVM_EXIT_MEMORY_FAULT is introduced:

  KVM_EXIT_MEMORY_FAULT will be used to report memory faults that appear to
  be implicit conversions.

  To allow for future possibilities where KVM reports KVM_EXIT_MEMORY_FAULT
  and fills run->memory_fault on _any_ unresolved fault, KVM returns
  "-EFAULT"

Thanks,
Yilun

> +     }
> +
> +     fault->max_level = min(kvm_max_level_for_order(max_order),
> +                            fault->max_level);
> +     fault->map_writable = !(fault->slot->flags & KVM_MEM_READONLY);
> +
> +     return RET_PF_CONTINUE;
> +}