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# hv_vcpu_get_sme_zt0_reg(_:_:)

Returns the current value of the vCPU ZT0 register in streaming Scalable Vector Extension (SVE) mode.

```
func hv_vcpu_get_sme_zt0_reg(_ vcpu: hv_vcpu_t, _ value: UnsafeMutablePointer<hv_sme_zt0_uchar64_t>) -> hv_return_t
```

## Parameters

`vcpu`

The ID of the vCPU instance.

`value`

The pointer to the retrieved register value.

## Return Value

`HV_SUCCESS` on success, an error code otherwise.

## Discussion

> Important:
> You need to call this on the owning thread.

This method returns an error if `PSTATE.ZA` is `0` (for example, when [`za_storage_enabled`](/documentation/Hypervisor/hv_vcpu_sme_state_t/za_storage_enabled) is `false`).

This method doesn’t require streaming SVE mode to be in an enabled state.

---

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