[PATCH v3 05/17] arm64: Don't enable VHE for the kernel if OVERRIDE_HVHE is set

Marc Zyngier
2023-06-09T16:22:18Z

If the OVERRIDE_HVHE SW override is set (as a precursor of
the KVM_HVHE capability), do not enable VHE for the kernel
and drop to EL1 as if VHE was either disabled or unavailable.

Further changes will enable VHE at EL2 only, with the kernel
still running at EL1.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kernel/hyp-stub.S | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
index 9439240c3fcf..5c71e1019545 100644
--- a/arch/arm64/kernel/hyp-stub.S
+++ b/arch/arm64/kernel/hyp-stub.S
@@ -82,7 +82,15 @@ SYM_CODE_START_LOCAL(__finalise_el2)
tbnz x1, #0, 1f

// Needs to be VHE capable, obviously
- check_override id_aa64mmfr1 ID_AA64MMFR1_EL1_VH_SHIFT 2f 1f x1 x2
+ check_override id_aa64mmfr1 ID_AA64MMFR1_EL1_VH_SHIFT 0f 1f x1 x2
+
+0: // Check whether we only want the hypervisor to run VHE, not the kernel
+ adr_l x1, arm64_sw_feature_override
+ ldr x2, [x1, FTR_OVR_VAL_OFFSET]
+ ldr x1, [x1, FTR_OVR_MASK_OFFSET]
+ and x2, x2, x1
+ ubfx x2, x2, #ARM64_SW_FEATURE_OVERRIDE_HVHE, #4
+ cbz x2, 2f

1: mov_q x0, HVC_STUB_ERR
eret
--
2.34.1