KVM: s390: fix and enforce return code handling for irq injections

kvm_s390_inject_program_int() and friends may fail if no memory is available.
This must be reported to the calling functions, so that this gets passed
down to user space which should fix the situation.
Alternatively we end up with guest state corruption.

So fix this and enforce return value checking by adding a __must_check
annotation to all of these function prototypes.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

arch/s390/kvm/intercept.c

@@ -45,10 +45,8 @@ static int handle_lctlg(struct kvm_vcpu *vcpu)
 	do {
 		rc = get_guest(vcpu, vcpu->arch.sie_block->gcr[reg],
 			       (u64 __user *) useraddr);
-		if (rc) {
-			kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
-			break;
-		}
+		if (rc)
+			return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 		useraddr += 8;
 		if (reg == reg3)
 			break;
@@ -79,10 +77,8 @@ static int handle_lctl(struct kvm_vcpu *vcpu)
 	reg = reg1;
 	do {
 		rc = get_guest(vcpu, val, (u32 __user *) useraddr);
-		if (rc) {
-			kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
-			break;
-		}
+		if (rc)
+			return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 		vcpu->arch.sie_block->gcr[reg] &= 0xffffffff00000000ul;
 		vcpu->arch.sie_block->gcr[reg] |= val;
 		useraddr += 4;

arch/s390/kvm/kvm-s390.c

@@ -633,8 +633,7 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
 		} else {
 			VCPU_EVENT(vcpu, 3, "%s", "fault in sie instruction");
 			trace_kvm_s390_sie_fault(vcpu);
-			kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
-			rc = 0;
+			rc = kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 		}
 	}
 	VCPU_EVENT(vcpu, 6, "exit sie icptcode %d",

arch/s390/kvm/kvm-s390.h

@@ -110,12 +110,12 @@ enum hrtimer_restart kvm_s390_idle_wakeup(struct hrtimer *timer);
 void kvm_s390_tasklet(unsigned long parm);
 void kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu);
 void kvm_s390_deliver_pending_machine_checks(struct kvm_vcpu *vcpu);
-int kvm_s390_inject_vm(struct kvm *kvm,
+int __must_check kvm_s390_inject_vm(struct kvm *kvm,
 				    struct kvm_s390_interrupt *s390int);
-int kvm_s390_inject_vcpu(struct kvm_vcpu *vcpu,
+int __must_check kvm_s390_inject_vcpu(struct kvm_vcpu *vcpu,
 				      struct kvm_s390_interrupt *s390int);
-int kvm_s390_inject_program_int(struct kvm_vcpu *vcpu, u16 code);
-int kvm_s390_inject_sigp_stop(struct kvm_vcpu *vcpu, int action);
+int __must_check kvm_s390_inject_program_int(struct kvm_vcpu *vcpu, u16 code);
+int __must_check kvm_s390_inject_sigp_stop(struct kvm_vcpu *vcpu, int action);
 struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,
 						    u64 cr6, u64 schid);
 

arch/s390/kvm/priv.c

@@ -36,31 +36,24 @@ static int handle_set_prefix(struct kvm_vcpu *vcpu)
 	operand2 = kvm_s390_get_base_disp_s(vcpu);
 
 	/* must be word boundary */
-	if (operand2 & 3) {
-		kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
-		goto out;
-	}
+	if (operand2 & 3)
+		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 
 	/* get the value */
-	if (get_guest(vcpu, address, (u32 __user *) operand2)) {
-		kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
-		goto out;
-	}
+	if (get_guest(vcpu, address, (u32 __user *) operand2))
+		return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 
 	address = address & 0x7fffe000u;
 
 	/* make sure that the new value is valid memory */
 	if (copy_from_guest_absolute(vcpu, &tmp, address, 1) ||
-	   (copy_from_guest_absolute(vcpu, &tmp, address + PAGE_SIZE, 1))) {
-		kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
-		goto out;
-	}
+	   (copy_from_guest_absolute(vcpu, &tmp, address + PAGE_SIZE, 1)))
+		return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 
 	kvm_s390_set_prefix(vcpu, address);
 
 	VCPU_EVENT(vcpu, 5, "setting prefix to %x", address);
 	trace_kvm_s390_handle_prefix(vcpu, 1, address);
-out:
 	return 0;
 }
 
@@ -74,49 +67,37 @@ static int handle_store_prefix(struct kvm_vcpu *vcpu)
 	operand2 = kvm_s390_get_base_disp_s(vcpu);
 
 	/* must be word boundary */
-	if (operand2 & 3) {
-		kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
-		goto out;
-	}
+	if (operand2 & 3)
+		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 
 	address = vcpu->arch.sie_block->prefix;
 	address = address & 0x7fffe000u;
 
 	/* get the value */
-	if (put_guest(vcpu, address, (u32 __user *)operand2)) {
-		kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
-		goto out;
-	}
+	if (put_guest(vcpu, address, (u32 __user *)operand2))
+		return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 
 	VCPU_EVENT(vcpu, 5, "storing prefix to %x", address);
 	trace_kvm_s390_handle_prefix(vcpu, 0, address);
-out:
 	return 0;
 }
 
 static int handle_store_cpu_address(struct kvm_vcpu *vcpu)
 {
 	u64 useraddr;
-	int rc;
 
 	vcpu->stat.instruction_stap++;
 
 	useraddr = kvm_s390_get_base_disp_s(vcpu);
 
-	if (useraddr & 1) {
-		kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
-		goto out;
-	}
+	if (useraddr & 1)
+		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 
-	rc = put_guest(vcpu, vcpu->vcpu_id, (u16 __user *)useraddr);
-	if (rc) {
-		kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
-		goto out;
-	}
+	if (put_guest(vcpu, vcpu->vcpu_id, (u16 __user *)useraddr))
+		return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 
 	VCPU_EVENT(vcpu, 5, "storing cpu address to %llx", useraddr);
 	trace_kvm_s390_handle_stap(vcpu, useraddr);
-out:
 	return 0;
 }
 
@@ -135,10 +116,8 @@ static int handle_tpi(struct kvm_vcpu *vcpu)
 	int cc;
 
 	addr = kvm_s390_get_base_disp_s(vcpu);
-	if (addr & 3) {
-		kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
-		goto out;
-	}
+	if (addr & 3)
+		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 	cc = 0;
 	inti = kvm_s390_get_io_int(vcpu->kvm, vcpu->run->s.regs.crs[6], 0);
 	if (!inti)
@@ -167,7 +146,6 @@ static int handle_tpi(struct kvm_vcpu *vcpu)
 	/* Set condition code and we're done. */
 	vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
 	vcpu->arch.sie_block->gpsw.mask |= (cc & 3ul) << 44;
-out:
 	return 0;
 }
 
@@ -237,12 +215,9 @@ static int handle_stfl(struct kvm_vcpu *vcpu)
 	rc = copy_to_guest(vcpu, offsetof(struct _lowcore, stfl_fac_list),
 			   &facility_list, sizeof(facility_list));
 	if (rc)
-		kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
-	else {
-		VCPU_EVENT(vcpu, 5, "store facility list value %x",
-			   facility_list);
+		return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
+	VCPU_EVENT(vcpu, 5, "store facility list value %x", facility_list);
 	trace_kvm_s390_handle_stfl(vcpu, facility_list);
-	}
 	return 0;
 }
 
@@ -317,25 +292,18 @@ static int handle_lpswe(struct kvm_vcpu *vcpu)
 static int handle_stidp(struct kvm_vcpu *vcpu)
 {
 	u64 operand2;
-	int rc;
 
 	vcpu->stat.instruction_stidp++;
 
 	operand2 = kvm_s390_get_base_disp_s(vcpu);
 
-	if (operand2 & 7) {
-		kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
-		goto out;
-	}
+	if (operand2 & 7)
+		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 
-	rc = put_guest(vcpu, vcpu->arch.stidp_data, (u64 __user *)operand2);
-	if (rc) {
-		kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
-		goto out;
-	}
+	if (put_guest(vcpu, vcpu->arch.stidp_data, (u64 __user *)operand2))
+		return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 
 	VCPU_EVENT(vcpu, 5, "%s", "store cpu id");
-out:
 	return 0;
 }
 
@@ -377,6 +345,7 @@ static int handle_stsi(struct kvm_vcpu *vcpu)
 	int sel2 = vcpu->run->s.regs.gprs[1] & 0xffff;
 	u64 operand2;
 	unsigned long mem;
+	int rc = 0;
 
 	vcpu->stat.instruction_stsi++;
 	VCPU_EVENT(vcpu, 4, "stsi: fc: %x sel1: %x sel2: %x", fc, sel1, sel2);
@@ -412,7 +381,7 @@ static int handle_stsi(struct kvm_vcpu *vcpu)
 	}
 
 	if (copy_to_guest_absolute(vcpu, operand2, (void *) mem, PAGE_SIZE)) {
-		kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
+		rc = kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 		goto out_mem;
 	}
 	trace_kvm_s390_handle_stsi(vcpu, fc, sel1, sel2, operand2);
@@ -425,7 +394,7 @@ static int handle_stsi(struct kvm_vcpu *vcpu)
 out_fail:
 	/* condition code 3 */
 	vcpu->arch.sie_block->gpsw.mask |= 3ul << 44;
-	return 0;
+	return rc;
 }
 
 static const intercept_handler_t b2_handlers[256] = {