[PATCH v7 18/23] KVM: arm64: Document HVC_VHE_RESTART stub hypercall

From: Marc Zyngier
Date: Mon Feb 08 2021 - 05:17:26 EST


For completeness, let's document the HVC_VHE_RESTART stub.

Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Acked-by: David Brazdil <dbrazdil@xxxxxxxxxx>
---
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..4d43fbc25195 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 means (command line
+ option, for example).
+
Any other value of r0/x0 triggers a hypervisor-specific handling,
which is not documented here.

--
2.29.2