x86/reboot: emergency callbacks are now registered by common KVM code

Guard them with CONFIG_KVM_X86_COMMON rather than the two vendor modules.
In practice this has no functional change, because CONFIG_KVM_X86_COMMON
is set if and only if at least one vendor-specific module is being built.
However, it is cleaner to specify CONFIG_KVM_X86_COMMON for functions that
are used in kvm.ko.

Reported-by: Linus Torvalds <[email protected]>
Fixes: 590b09b ("KVM: x86: Register "emergency disable" callbacks when virt is enabled")
Fixes: 6d55a94 ("x86/reboot: Unconditionally define cpu_emergency_virt_cb typedef")
Signed-off-by: Paolo Bonzini <[email protected]>

Author: bonzini

arch/x86/include/asm/reboot.h

@@ -26,13 +26,13 @@ void __noreturn machine_real_restart(unsigned int type);
 #define MRR_APM		1
 
 typedef void (cpu_emergency_virt_cb)(void);
-#if IS_ENABLED(CONFIG_KVM_INTEL) || IS_ENABLED(CONFIG_KVM_AMD)
+#if IS_ENABLED(CONFIG_KVM_X86)
 void cpu_emergency_register_virt_callback(cpu_emergency_virt_cb *callback);
 void cpu_emergency_unregister_virt_callback(cpu_emergency_virt_cb *callback);
 void cpu_emergency_disable_virtualization(void);
 #else
 static inline void cpu_emergency_disable_virtualization(void) {}
-#endif /* CONFIG_KVM_INTEL || CONFIG_KVM_AMD */
+#endif /* CONFIG_KVM_X86 */
 
 typedef void (*nmi_shootdown_cb)(int, struct pt_regs*);
 void nmi_shootdown_cpus(nmi_shootdown_cb callback);

arch/x86/kernel/reboot.c

@@ -530,7 +530,7 @@ static inline void kb_wait(void)
 
 static inline void nmi_shootdown_cpus_on_restart(void);
 
-#if IS_ENABLED(CONFIG_KVM_INTEL) || IS_ENABLED(CONFIG_KVM_AMD)
+#if IS_ENABLED(CONFIG_KVM_X86)
 /* RCU-protected callback to disable virtualization prior to reboot. */
 static cpu_emergency_virt_cb __rcu *cpu_emergency_virt_callback;
 
@@ -600,7 +600,7 @@ static void emergency_reboot_disable_virtualization(void)
 }
 #else
 static void emergency_reboot_disable_virtualization(void) { }
-#endif /* CONFIG_KVM_INTEL || CONFIG_KVM_AMD */
+#endif /* CONFIG_KVM_X86 */
 
 void __attribute__((weak)) mach_reboot_fixups(void)
 {