KVM: s390: Fixed priority of execution in STSI

Added some missing validity checks for the operands and fixed the
priority of exceptions for some function codes according to the
"Principles of Operation" document.

Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/s390/kvm/priv.c

@@ -385,16 +385,27 @@ static int handle_stsi(struct kvm_vcpu *vcpu)
 	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
 		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
 
-	operand2 = kvm_s390_get_base_disp_s(vcpu);
+	if (fc > 3) {
+		vcpu->arch.sie_block->gpsw.mask |= 3ul << 44;	  /* cc 3 */
+		return 0;
+	}
 
-	if (operand2 & 0xfff && fc > 0)
+	if (vcpu->run->s.regs.gprs[0] & 0x0fffff00
+	    || vcpu->run->s.regs.gprs[1] & 0xffff0000)
 		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 
-	switch (fc) {
-	case 0:
+	if (fc == 0) {
 		vcpu->run->s.regs.gprs[0] = 3 << 28;
-		vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
+		vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);  /* cc 0 */
 		return 0;
+	}
+
+	operand2 = kvm_s390_get_base_disp_s(vcpu);
+
+	if (operand2 & 0xfff)
+		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
+
+	switch (fc) {
 	case 1: /* same handling for 1 and 2 */
 	case 2:
 		mem = get_zeroed_page(GFP_KERNEL);
@@ -411,8 +422,6 @@ static int handle_stsi(struct kvm_vcpu *vcpu)
 			goto out_no_data;
 		handle_stsi_3_2_2(vcpu, (void *) mem);
 		break;
-	default:
-		goto out_no_data;
 	}
 
 	if (copy_to_guest_absolute(vcpu, operand2, (void *) mem, PAGE_SIZE)) {