KVM: s390: gs support for kvm guests

This patch adds guarded storage support for KVM guest. We need to
setup the necessary control blocks, the kvm_run structure for the
new registers, the necessary wrappers for VSIE, as well as the
machine check save areas.
GS is enabled lazily and the register saving and reloading is done in
KVM code.  As this feature adds new content for migration, we provide
a new capability for enablement (KVM_CAP_S390_GS).

Signed-off-by: Fan Zhang <zhangfan@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/vsie.c

@@ -329,6 +329,11 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	/* Instruction Execution Prevention */
 	if (test_kvm_facility(vcpu->kvm, 130))
 		scb_s->ecb2 |= scb_o->ecb2 & ECB2_IEP;
+	/* Guarded Storage */
+	if (test_kvm_facility(vcpu->kvm, 133)) {
+		scb_s->ecb |= scb_o->ecb & ECB_GS;
+		scb_s->ecd |= scb_o->ecd & ECD_HOSTREGMGMT;
+	}
 	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_SIIF))
 		scb_s->eca |= scb_o->eca & ECA_SII;
 	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_IB))
@@ -496,6 +501,13 @@ static void unpin_blocks(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 		unpin_guest_page(vcpu->kvm, gpa, hpa);
 		scb_s->riccbd = 0;
 	}
+
+	hpa = scb_s->sdnxo;
+	if (hpa) {
+		gpa = scb_o->sdnxo;
+		unpin_guest_page(vcpu->kvm, gpa, hpa);
+		scb_s->sdnxo = 0;
+	}
 }
 
 /*
@@ -590,6 +602,33 @@ static int pin_blocks(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 			goto unpin;
 		scb_s->riccbd = hpa;
 	}
+	if ((scb_s->ecb & ECB_GS) && !(scb_s->ecd & ECD_HOSTREGMGMT)) {
+		unsigned long sdnxc;
+
+		gpa = scb_o->sdnxo & ~0xfUL;
+		sdnxc = scb_o->sdnxo & 0xfUL;
+		if (!gpa || !(gpa & ~0x1fffUL)) {
+			rc = set_validity_icpt(scb_s, 0x10b0U);
+			goto unpin;
+		}
+		if (sdnxc < 6 || sdnxc > 12) {
+			rc = set_validity_icpt(scb_s, 0x10b1U);
+			goto unpin;
+		}
+		if (gpa & ((1 << sdnxc) - 1)) {
+			rc = set_validity_icpt(scb_s, 0x10b2U);
+			goto unpin;
+		}
+		/* Due to alignment rules (checked above) this cannot
+		 * cross page boundaries
+		 */
+		rc = pin_guest_page(vcpu->kvm, gpa, &hpa);
+		if (rc == -EINVAL)
+			rc = set_validity_icpt(scb_s, 0x10b0U);
+		if (rc)
+			goto unpin;
+		scb_s->sdnxo = hpa;
+	}
 	return 0;
 unpin:
 	unpin_blocks(vcpu, vsie_page);