From 166cc2a4be0d80075d379b30d3e84895c878a1a8 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 8 Feb 2021 09:57:27 +0000 Subject: [PATCH] KVM: arm64: Document HVC_VHE_RESTART stub hypercall For completeness, let's document the HVC_VHE_RESTART stub. Signed-off-by: Marc Zyngier Acked-by: David Brazdil Link: https://lore.kernel.org/r/20210208095732.3267263-19-maz@kernel.org Signed-off-by: Will Deacon --- 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.