....
> +static int private_memslot_fault(struct kvm_vcpu *vcpu,
> + phys_addr_t fault_ipa,
> + struct kvm_memory_slot *memslot)
> +{
> + struct kvm *kvm = vcpu->kvm;
> + gpa_t gpa = kvm_gpa_from_fault(kvm, fault_ipa);
> + gfn_t gfn = gpa >> PAGE_SHIFT;
> + bool priv_exists = kvm_mem_is_private(kvm, gfn);
> + struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
> + kvm_pfn_t pfn;
> + int ret;
> + /*
> + * For Realms, the shared address is an alias of the private GPA with
> + * the top bit set. Thus is the fault address matches the GPA then it
> + * is the private alias.
> + */
> + bool is_priv_gfn = (gpa == fault_ipa);
> +
> + if (priv_exists != is_priv_gfn) {
> + kvm_prepare_memory_fault_exit(vcpu,
> + gpa,
> + PAGE_SIZE,
> + kvm_is_write_fault(vcpu),
> + false, is_priv_gfn);
> +
> + return -EFAULT;
> + }
>
If we want an exit to VMM and handle the fault, should we have the return value 0? For
kvmtool we do have the KVM_RUN ioctl doing the below
err = ioctl(vcpu->vcpu_fd, KVM_RUN, 0);
if (err < 0 && (errno != EINTR && errno != EAGAIN))
die_perror("KVM_RUN failed");
Qemu did end up adding the below condition.
if (!(run_ret == -EFAULT && run->exit_reason == KVM_EXIT_MEMORY_FAULT)) {
fprintf(stderr, "error: kvm run failed %s\n",
strerror(-run_ret));
so should we fix kvmtool. We may possibly want to add other exit_reason
and it would be useful to not require similar VMM changes for these exit_reason.
> +
> + if (!is_priv_gfn) {
> + /* Not a private mapping, handling normally */
> + return -EINVAL;
> + }
> +
-aneesh
