x86/xen: add CONFIG_XEN_PV to Kconfig

All code to support Xen PV will get under this new option. For the
beginning, check for it in the common code.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index 76b6dbd..5bb1434 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -6,7 +6,6 @@
 	bool "Xen guest support"
 	depends on PARAVIRT
 	select PARAVIRT_CLOCK
-	select XEN_HAVE_PVMMU
 	select XEN_HAVE_VPMU
 	depends on X86_64 || (X86_32 && X86_PAE)
 	depends on X86_LOCAL_APIC && X86_TSC
@@ -15,18 +14,32 @@
 	  kernel to boot in a paravirtualized environment under the
 	  Xen hypervisor.
 
+config XEN_PV
+	bool "Xen PV guest support"
+	default y
+	depends on XEN
+	select XEN_HAVE_PVMMU
+	help
+	  Support running as a Xen PV guest.
+
 config XEN_DOM0
-	def_bool y
-	depends on XEN && PCI_XEN && SWIOTLB_XEN
+	bool "Xen PV Dom0 support"
+	default y
+	depends on XEN_PV && PCI_XEN && SWIOTLB_XEN
 	depends on X86_IO_APIC && ACPI && PCI
+	help
+	  Support running as a Xen PV Dom0 guest.
 
 config XEN_PVHVM
-	def_bool y
+	bool "Xen PVHVM guest support"
+	default y
 	depends on XEN && PCI && X86_LOCAL_APIC
+	help
+	  Support running as a Xen PVHVM guest.
 
 config XEN_512GB
 	bool "Limit Xen pv-domain memory to 512GB"
-	depends on XEN && X86_64
+	depends on XEN_PV && X86_64
 	default y
 	help
 	  Limit paravirtualized user domains to 512GB of RAM.