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[16/17] KVM: arm64: Document HVC_VHE_RESTART stub hypercall

Message ID 20201228104958.1848833-17-maz@kernel.org (mailing list archive)
State New, archived
Headers show
Series arm64: Early CPU feature override, and an application to VHE | expand

Commit Message

Marc Zyngier Dec. 28, 2020, 10:49 a.m. UTC
For completeness, let's document the HVC_VHE_RESTART stub.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 Documentation/virt/kvm/arm/hyp-abi.rst | 9 +++++++++
 1 file changed, 9 insertions(+)
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Patch

diff --git a/Documentation/virt/kvm/arm/hyp-abi.rst b/Documentation/virt/kvm/arm/hyp-abi.rst
index 83cadd8186fa..3961c529769b 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 conditionned by the CPU supporting VHE, the EL2 MMU
+  being off, and VHE not being disabled by any other mean (comment line option,
+  for example).
+
 Any other value of r0/x0 triggers a hypervisor-specific handling,
 which is not documented here.