KVM: s390: Fix possible host kernel bug on lctl(g) handling

The lctl(g) instructions require a specific alignment for the parameters.
The architecture requires a specification program check if these alignments
are not used. Enforcing this alignment also removes a possible host BUG,
since the get_guest functions check for proper alignment and emits a BUG.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

arch/s390/kvm/intercept.c

@@ -38,6 +38,9 @@ static int handle_lctlg(struct kvm_vcpu *vcpu)
 	if (base2)
 		useraddr += vcpu->arch.guest_gprs[base2];
 
+	if (useraddr & 7)
+		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
+
 	reg = reg1;
 
 	VCPU_EVENT(vcpu, 5, "lctlg r1:%x, r3:%x,b2:%x,d2:%x", reg1, reg3, base2,
@@ -74,6 +77,9 @@ static int handle_lctl(struct kvm_vcpu *vcpu)
 	if (base2)
 		useraddr += vcpu->arch.guest_gprs[base2];
 
+	if (useraddr & 3)
+		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
+
 	VCPU_EVENT(vcpu, 5, "lctl r1:%x, r3:%x,b2:%x,d2:%x", reg1, reg3, base2,
 		   disp2);