---
title: "hv_vcpu_set_vtimer_mask(_:_:)"
framework: hypervisor
role: symbol
role_heading: Function
path: "hypervisor/hv_vcpu_set_vtimer_mask(_:_:)"
---

# hv_vcpu_set_vtimer_mask(_:_:)

Sets or clears the virtual timer mask.

## Declaration

```swift
func hv_vcpu_set_vtimer_mask(_ vcpu: hv_vcpu_t, _ vtimer_is_masked: Bool) -> hv_return_t
```

## Parameters

- `vcpu`: The ID of the vCPU instance.
- `vtimer_is_masked`: A Boolean value that indicates whether the vTimer has a mask set.

## Return Value

Return Value HV_SUCCESS if the operation was successful, otherwise an error code specified in hv_return_t.

## Discussion

Discussion After hv_vcpu_run(_:) returns with the exit reason HV_EXIT_REASON_VTIMER_ACTIVATED, the timer is masked automatically. The vCPU won’t exit with this reason again until the mask is cleared even when calling hv_vcpu_run() with the vTimer interrupt in a pending state. After receiving a HV_EXIT_REASON_VTIMER_ACTIVATED exit reason, the caller of hv_vcpu_run() needs to make the interrupts to the vTimer pending in the guest’s virtual interrupt controller. It also needs to detect when the guest has serviced this interrupt. For example, call this function when emulating a GIC when deactivating an interrupt whose ID matches that of the vTimer.

## See Also

### Timer functions

- [hv_vcpu_get_vtimer_mask(_:_:)](hypervisor/hv_vcpu_get_vtimer_mask(_:_:).md)
- [hv_vcpu_get_vtimer_offset(_:_:)](hypervisor/hv_vcpu_get_vtimer_offset(_:_:).md)
- [hv_vcpu_set_vtimer_offset(_:_:)](hypervisor/hv_vcpu_set_vtimer_offset(_:_:).md)