If the host initialized the Ultravisor, we can set stfle bit 161
(protected virtual IPL enhancements facility), which indicates, that
the IPL subcodes 8, 9 and are valid. These subcodes are used by a
normal guest to set/retrieve a IPIB of type 5 and transition into
protected mode.
Once in protected mode, the VM will loose the facility bit, as each
boot into protected mode has to go through non-protected. There is no
secure re-ipl with subcode 10 without a previous subcode 3.
In protected mode, there is no subcode 4 available, as the VM has no
more access to its memory from non-protected mode. I.e. each IPL
clears.
Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
---
arch/s390/kvm/diag.c | 6 ++++++
arch/s390/kvm/kvm-s390.c | 5 +++++
2 files changed, 11 insertions(+)
diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
index 3fb54ec2cf3e..b951dbdcb6a0 100644
--- a/arch/s390/kvm/diag.c
+++ b/arch/s390/kvm/diag.c
@@ -197,6 +197,12 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
case 4:
vcpu->run->s390_reset_flags = 0;
break;
+ case 8:
+ case 9:
+ case 10:
+ if (!test_kvm_facility(vcpu->kvm, 161))
+ return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
+ /* fall through */
default:
return -EOPNOTSUPP;
}
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 500972a1f742..8947f1812b12 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2590,6 +2590,11 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
if (css_general_characteristics.aiv && test_facility(65))
set_kvm_facility(kvm->arch.model.fac_mask, 65);
+ if (is_prot_virt_host()) {
+ set_kvm_facility(kvm->arch.model.fac_mask, 161);
+ set_kvm_facility(kvm->arch.model.fac_list, 161);
+ }
+
kvm->arch.model.cpuid = kvm_s390_get_initial_cpuid();
kvm->arch.model.ibc = sclp.ibc & 0x0fff;
--
2.20.1
