arm/kvm: Cleanup KVM_ARM_MAX_VCPUS logic

Commit d21a1c83 (ARM: KVM: define KVM_ARM_MAX_VCPUS
unconditionally) changed the Kconfig logic for KVM_ARM_MAX_VCPUS to work around a
build error arising from the use of KVM_ARM_MAX_VCPUS when CONFIG_KVM=n.  The
resulting Kconfig logic is a bit awkward and leaves a KVM_ARM_MAX_VCPUS always
defined in the kernel config file.

This change reverts the Kconfig logic back and adds a simple preprocessor
conditional in kvm_host.h to handle when CONFIG_KVM_ARM_MAX_VCPUS is undefined.
Signed-off-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

arch/arm/include/asm/kvm_host.h

@@ -25,7 +25,12 @@
 #include <asm/fpstate.h>
 #include <kvm/arm_arch_timer.h>
 
+#if defined(CONFIG_KVM_ARM_MAX_VCPUS)
 #define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS
+#else
+#define KVM_MAX_VCPUS 0
+#endif
+
 #define KVM_USER_MEM_SLOTS 32
 #define KVM_PRIVATE_MEM_SLOTS 4
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1

arch/arm/kvm/Kconfig

@@ -41,9 +41,9 @@ config KVM_ARM_HOST
 	  Provides host support for ARM processors.
 
 config KVM_ARM_MAX_VCPUS
-	int "Number maximum supported virtual CPUs per VM" if KVM_ARM_HOST
-	default 4 if KVM_ARM_HOST
-	default 0
+	int "Number maximum supported virtual CPUs per VM"
+	depends on KVM_ARM_HOST
+	default 4
 	help
 	  Static number of max supported virtual CPUs per VM.