KVM: s390: vsie: Do not shadow CRYCB when no AP and no keys

When the guest do not have AP instructions nor Key management
we should return without shadowing the CRYCB.

We did not check correctly in the past.

Fixes: b10bd9a2 ("s390: vsie: Use effective CRYCBD.31 to check CRYCBD validity")
Fixes: 6ee74098 ("KVM: s390: vsie: allow CRYCB FORMAT-0")
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Message-Id: <1556269010-22258-1-git-send-email-pmorel@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/vsie.c

@@ -290,6 +290,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	u8 ecb3_flags;
 	u32 ecd_flags;
 	int apie_h;
+	int apie_s;
 	int key_msk = test_kvm_facility(vcpu->kvm, 76);
 	int fmt_o = crycbd_o & CRYCB_FORMAT_MASK;
 	int fmt_h = vcpu->arch.sie_block->crycbd & CRYCB_FORMAT_MASK;
@@ -298,7 +299,8 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	scb_s->crycbd = 0;
 
 	apie_h = vcpu->arch.sie_block->eca & ECA_APIE;
-	if (!apie_h && (!key_msk || fmt_o == CRYCB_FORMAT0))
+	apie_s = apie_h & scb_o->eca;
+	if (!apie_s && (!key_msk || (fmt_o == CRYCB_FORMAT0)))
 		return 0;
 
 	if (!crycb_addr)
@@ -309,7 +311,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 		    ((crycb_addr + 128) & PAGE_MASK))
 			return set_validity_icpt(scb_s, 0x003CU);
 
-	if (apie_h && (scb_o->eca & ECA_APIE)) {
+	if (apie_s) {
 		ret = setup_apcb(vcpu, &vsie_page->crycb, crycb_addr,
 				 vcpu->kvm->arch.crypto.crycb,
 				 fmt_o, fmt_h);