KVM: s390: vsie: support shared IPTE-interlock facility

As we forward the whole SCA provided by guest 2, we can directly forward
SIIF if available.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/include/uapi/asm/kvm.h

@@ -100,6 +100,7 @@ struct kvm_s390_vm_cpu_machine {
 #define KVM_S390_VM_CPU_FEAT_ESOP	0
 #define KVM_S390_VM_CPU_FEAT_SIEF2	1
 #define KVM_S390_VM_CPU_FEAT_64BSCAO	2
+#define KVM_S390_VM_CPU_FEAT_SIIF	3
 struct kvm_s390_vm_cpu_feat {
 	__u64 feat[16];
 };

arch/s390/kvm/kvm-s390.c

@@ -267,6 +267,8 @@ static void kvm_s390_cpu_feat_init(void)
 	allow_cpu_feat(KVM_S390_VM_CPU_FEAT_SIEF2);
 	if (sclp.has_64bscao)
 		allow_cpu_feat(KVM_S390_VM_CPU_FEAT_64BSCAO);
+	if (sclp.has_siif)
+		allow_cpu_feat(KVM_S390_VM_CPU_FEAT_SIIF);
 }
 
 int kvm_arch_init(void *opaque)

arch/s390/kvm/vsie.c

@@ -315,6 +315,8 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	/* Run-time-Instrumentation */
 	if (test_kvm_facility(vcpu->kvm, 64))
 		scb_s->ecb3 |= scb_o->ecb3 & 0x01U;
+	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_SIIF))
+		scb_s->eca |= scb_o->eca & 0x00000001U;
 
 	prepare_ibc(vcpu, vsie_page);
 	rc = shadow_crycb(vcpu, vsie_page);