arm64: Don't enable VHE for the kernel if OVERRIDE_HVHE is set

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>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20230609162200.2024064-6-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
index 9439240..5c71e10 100644 (file)
--- 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