x86: KVM guest: merge CONFIG_KVM_CLOCK into CONFIG_KVM_GUEST

The distinction between CONFIG_KVM_CLOCK and CONFIG_KVM_GUEST is
not so clear anymore, as demonstrated by recent bugs caused by poor
handling of on/off combinations of these options.

Merge CONFIG_KVM_CLOCK into CONFIG_KVM_GUEST.
Reported-By: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

arch/x86/Kconfig

@@ -573,23 +573,18 @@ config PARAVIRT_TIME_ACCOUNTING
 
 source "arch/x86/xen/Kconfig"
 
-config KVM_CLOCK
-	bool "KVM paravirtualized clock"
-	select PARAVIRT
-	select PARAVIRT_CLOCK
-	---help---
-	  Turning on this option will allow you to run a paravirtualized clock
-	  when running over the KVM hypervisor. Instead of relying on a PIT
-	  (or probably other) emulation by the underlying device model, the host
-	  provides the guest with timing infrastructure such as time of day, and
-	  system time
-
 config KVM_GUEST
-	bool "KVM Guest support"
+	bool "KVM Guest support (including kvmclock)"
+	select PARAVIRT
 	select PARAVIRT
+	select PARAVIRT_CLOCK
+	default y if PARAVIRT_GUEST
 	---help---
 	  This option enables various optimizations for running under the KVM
-	  hypervisor.
+	  hypervisor. It includes a paravirtualized clock, so that instead
+	  of relying on a PIT (or probably other) emulation by the
+	  underlying device model, the host provides the guest with
+	  timing infrastructure such as time of day, and system time
 
 source "arch/x86/lguest/Kconfig"
 

arch/x86/include/asm/kvm_para.h

@@ -102,14 +102,14 @@ struct kvm_vcpu_pv_apf_data {
 extern void kvmclock_init(void);
 extern int kvm_register_clock(char *txt);
 
-#ifdef CONFIG_KVM_CLOCK
+#ifdef CONFIG_KVM_GUEST
 bool kvm_check_and_clear_guest_paused(void);
 #else
 static inline bool kvm_check_and_clear_guest_paused(void)
 {
 	return false;
 }
-#endif /* CONFIG_KVMCLOCK */
+#endif /* CONFIG_KVM_GUEST */
 
 /* This instruction is vmcall.  On non-VT architectures, it will generate a
  * trap that we will then rewrite to the appropriate instruction.

arch/x86/kernel/Makefile

@@ -81,8 +81,7 @@ obj-$(CONFIG_DEBUG_RODATA_TEST)	+= test_rodata.o
 obj-$(CONFIG_DEBUG_NX_TEST)	+= test_nx.o
 obj-$(CONFIG_DEBUG_NMI_SELFTEST) += nmi_selftest.o
 
-obj-$(CONFIG_KVM_GUEST)		+= kvm.o
-obj-$(CONFIG_KVM_CLOCK)		+= kvmclock.o
+obj-$(CONFIG_KVM_GUEST)		+= kvm.o kvmclock.o
 obj-$(CONFIG_PARAVIRT)		+= paravirt.o paravirt_patch_$(BITS).o
 obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= paravirt-spinlocks.o
 obj-$(CONFIG_PARAVIRT_CLOCK)	+= pvclock.o

arch/x86/kernel/kvm.c

@@ -397,9 +397,7 @@ void kvm_disable_steal_time(void)
 #ifdef CONFIG_SMP
 static void __init kvm_smp_prepare_boot_cpu(void)
 {
-#ifdef CONFIG_KVM_CLOCK
 	WARN_ON(kvm_register_clock("primary cpu clock"));
-#endif
 	kvm_guest_cpu_init();
 	native_smp_prepare_boot_cpu();
 }

arch/x86/kernel/setup.c

@@ -957,7 +957,7 @@ void __init setup_arch(char **cmdline_p)
 	initmem_init();
 	memblock_find_dma_reserve();
 
-#ifdef CONFIG_KVM_CLOCK
+#ifdef CONFIG_KVM_GUEST
 	kvmclock_init();
 #endif