KVM: arm64: Use build-time defines in has_vhe()

Build system compiles hyp code with macros specifying if the code belongs
to VHE or nVHE. Use these macros to evaluate has_vhe() at compile time.
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200625131420.71444-5-dbrazdil@google.com

arch/arm64/include/asm/virt.h

@@ -85,10 +85,17 @@ static inline bool is_kernel_in_hyp_mode(void)
 
 static __always_inline bool has_vhe(void)
 {
-	if (cpus_have_final_cap(ARM64_HAS_VIRT_HOST_EXTN))
+	/*
+	 * The following macros are defined for code specic to VHE/nVHE.
+	 * If has_vhe() is inlined into those compilation units, it can
+	 * be determined statically. Otherwise fall back to caps.
+	 */
+	if (__is_defined(__KVM_VHE_HYPERVISOR__))
 		return true;
-
-	return false;
+	else if (__is_defined(__KVM_NVHE_HYPERVISOR__))
+		return false;
+	else
+		return cpus_have_final_cap(ARM64_HAS_VIRT_HOST_EXTN);
 }
 
 #endif /* __ASSEMBLY__ */