KVM: x86: Force KVM_WERROR if the global WERROR is enabled

Force KVM_WERROR if the global WERROR is enabled to avoid pestering the
user about a Kconfig that will ultimately be ignored.  Force KVM_WERROR
instead of making it mutually exclusive with WERROR to avoid generating a
.config builds KVM with -Werror, but has KVM_WERROR=n.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240517180341.974251-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/Kconfig

@@ -44,6 +44,7 @@ config KVM
 	select KVM_VFIO
 	select HAVE_KVM_PM_NOTIFIER if PM
 	select KVM_GENERIC_HARDWARE_ENABLING
+	select KVM_WERROR if WERROR
 	help
 	  Support hosting fully virtualized guest machines using hardware
 	  virtualization extensions.  You will need a fairly recent
@@ -66,7 +67,7 @@ config KVM_WERROR
 	# FRAME_WARN, i.e. KVM_WERROR=y with KASAN=y requires special tuning.
 	# Building KVM with -Werror and KASAN is still doable via enabling
 	# the kernel-wide WERROR=y.
-	depends on KVM && EXPERT && !KASAN
+	depends on KVM && ((EXPERT && !KASAN) || WERROR)
 	help
 	  Add -Werror to the build flags for KVM.