Re: [PATCH v4 17/21] KVM: arm64: Document HVC_VHE_RESTART stub hypercall

David Brazdil
2021-01-18T13:30:51Z

On Mon, Jan 18, 2021 at 09:45:29AM +0000, Marc Zyngier wrote:
> For completeness, let's document the HVC_VHE_RESTART stub.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>

> ---
> Documentation/virt/kvm/arm/hyp-abi.rst | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/Documentation/virt/kvm/arm/hyp-abi.rst b/Documentation/virt/kvm/arm/hyp-abi.rst
> index 83cadd8186fa..1ba628baf11b 100644
> --- a/Documentation/virt/kvm/arm/hyp-abi.rst
> +++ b/Documentation/virt/kvm/arm/hyp-abi.rst
> @@ -58,6 +58,15 @@ these functions (see arch/arm{,64}/include/asm/virt.h):
> into place (arm64 only), and jump to the restart address while at HYP/EL2.
> This hypercall is not expected to return to its caller.
>
> +* ::
> +
> + x0 = HVC_VHE_RESTART (arm64 only)
> +
> + Attempt to upgrade the kernel's exception level from EL1 to EL2 by enabling
> + the VHE mode. This is conditioned by the CPU supporting VHE, the EL2 MMU
> + being off, and VHE not being disabled by any other mean (comment line option,
'means' (both singular and plural), and 'command line'

> + for example).
> +
> Any other value of r0/x0 triggers a hypervisor-specific handling,
> which is not documented here.
>
> --
> 2.29.2