From 261cd5ed934e6923187cf1c9eaa6cb63f2b81212 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 21 Jul 2023 13:18:48 -0700 Subject: [PATCH] x86/reboot: Expose VMCS crash hooks if and only if KVM_{INTEL,AMD} is enabled Expose the crash/reboot hooks used by KVM to disable virtualization in hardware and unblock INIT only if there's a potential in-tree user, i.e. either KVM_INTEL or KVM_AMD is enabled. Reviewed-by: Kai Huang Link: https://lore.kernel.org/r/20230721201859.2307736-9-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/include/asm/reboot.h | 4 ++++ arch/x86/kernel/reboot.c | 5 ++++- 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/reboot.h b/arch/x86/include/asm/reboot.h index 74c6a624d166..6536873f8fc0 100644 --- a/arch/x86/include/asm/reboot.h +++ b/arch/x86/include/asm/reboot.h @@ -25,10 +25,14 @@ void __noreturn machine_real_restart(unsigned int type); #define MRR_BIOS 0 #define MRR_APM 1 +#if IS_ENABLED(CONFIG_KVM_INTEL) || IS_ENABLED(CONFIG_KVM_AMD) typedef void (cpu_emergency_virt_cb)(void); 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 */ typedef void (*nmi_shootdown_cb)(int, struct pt_regs*); void nmi_shootdown_cpus(nmi_shootdown_cb callback); diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index 98e5db3fd7f4..830425e6d38e 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -529,6 +529,7 @@ 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) /* RCU-protected callback to disable virtualization prior to reboot. */ static cpu_emergency_virt_cb __rcu *cpu_emergency_virt_callback; @@ -596,7 +597,9 @@ static void emergency_reboot_disable_virtualization(void) nmi_shootdown_cpus_on_restart(); } } - +#else +static void emergency_reboot_disable_virtualization(void) { } +#endif /* CONFIG_KVM_INTEL || CONFIG_KVM_AMD */ void __attribute__((weak)) mach_reboot_fixups(void) {