On Sat, May 01, 2021, Paolo Bonzini wrote:
> - make it completely independent from migration, i.e. it's just a facet of
> MSR_KVM_PAGE_ENC_STATUS saying whether the bitmap is up-to-date. It would
> use CPUID bit as the encryption status bitmap and have no code at all in KVM
> (userspace needs to set up the filter and implement everything).
If the bit is purely a "page encryption status is up-to-date", what about
overloading KVM_HC_PAGE_ENC_STATUS to handle that status update as well? That
would eliminate my biggest complaint about having what is effectively a single
paravirt feature split into two separate, but intertwined chunks of ABI.
#define KVM_HC_PAGE_ENC_UPDATE 12
#define KVM_HC_PAGE_ENC_REGION_UPDATE 0 /* encrypted vs. plain text */
#define KVM_HC_PAGE_ENC_STATUS_UPDATE 1 /* up-to-date vs. stale */
ret = -KVM_ENOSYS;
if (!vcpu->kvm->arch.hypercall_exit_enabled)
break;
ret = -EINVAL;
if (a0 == KVM_HC_PAGE_ENC_REGION_UPDATE) {
u64 gpa = a1, npages = a2;
if (!PAGE_ALIGNED(gpa) || !npages ||
gpa_to_gfn(gpa) + npages <= gpa_to_gfn(gpa))
break;
} else if (a0 != KVM_HC_PAGE_ENC_STATUS_UPDATE) {
break;
}
vcpu->run->exit_reason = KVM_EXIT_HYPERCALL;
vcpu->run->hypercall.nr = KVM_HC_PAGE_ENC_STATUS;
vcpu->run->hypercall.args[0] = a0;
vcpu->run->hypercall.args[1] = a1;
vcpu->run->hypercall.args[2] = a2;
vcpu->run->hypercall.args[3] = a3;
vcpu->run->hypercall.longmode = op_64_bit;
vcpu->arch.complete_userspace_io = complete_hypercall_exit;
return 0;
