diff options
Diffstat (limited to 'arch/x86/kernel/reboot.c')
-rw-r--r-- | arch/x86/kernel/reboot.c | 66 |
1 files changed, 50 insertions, 16 deletions
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index 3adbe97015c1..830425e6d38e 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -22,7 +22,6 @@ #include <asm/reboot_fixups.h> #include <asm/reboot.h> #include <asm/pci_x86.h> -#include <asm/virtext.h> #include <asm/cpu.h> #include <asm/nmi.h> #include <asm/smp.h> @@ -530,9 +529,54 @@ 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; + +void cpu_emergency_register_virt_callback(cpu_emergency_virt_cb *callback) +{ + if (WARN_ON_ONCE(rcu_access_pointer(cpu_emergency_virt_callback))) + return; + + rcu_assign_pointer(cpu_emergency_virt_callback, callback); +} +EXPORT_SYMBOL_GPL(cpu_emergency_register_virt_callback); + +void cpu_emergency_unregister_virt_callback(cpu_emergency_virt_cb *callback) +{ + if (WARN_ON_ONCE(rcu_access_pointer(cpu_emergency_virt_callback) != callback)) + return; + + rcu_assign_pointer(cpu_emergency_virt_callback, NULL); + synchronize_rcu(); +} +EXPORT_SYMBOL_GPL(cpu_emergency_unregister_virt_callback); + +/* + * Disable virtualization, i.e. VMX or SVM, to ensure INIT is recognized during + * reboot. VMX blocks INIT if the CPU is post-VMXON, and SVM blocks INIT if + * GIF=0, i.e. if the crash occurred between CLGI and STGI. + */ +void cpu_emergency_disable_virtualization(void) +{ + cpu_emergency_virt_cb *callback; + + /* + * IRQs must be disabled as KVM enables virtualization in hardware via + * function call IPIs, i.e. IRQs need to be disabled to guarantee + * virtualization stays disabled. + */ + lockdep_assert_irqs_disabled(); + + rcu_read_lock(); + callback = rcu_dereference(cpu_emergency_virt_callback); + if (callback) + callback(); + rcu_read_unlock(); +} + static void emergency_reboot_disable_virtualization(void) { - /* Just make sure we won't change CPUs while doing this */ local_irq_disable(); /* @@ -545,7 +589,7 @@ static void emergency_reboot_disable_virtualization(void) * Do the NMI shootdown even if virtualization is off on _this_ CPU, as * other CPUs may have virtualization enabled. */ - if (cpu_has_vmx() || cpu_has_svm(NULL)) { + if (rcu_access_pointer(cpu_emergency_virt_callback)) { /* Safely force _this_ CPU out of VMX/SVM operation. */ cpu_emergency_disable_virtualization(); @@ -553,7 +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) { @@ -787,21 +833,9 @@ void machine_crash_shutdown(struct pt_regs *regs) } #endif - /* This is the CPU performing the emergency shutdown work. */ int crashing_cpu = -1; -/* - * Disable virtualization, i.e. VMX or SVM, to ensure INIT is recognized during - * reboot. VMX blocks INIT if the CPU is post-VMXON, and SVM blocks INIT if - * GIF=0, i.e. if the crash occurred between CLGI and STGI. - */ -void cpu_emergency_disable_virtualization(void) -{ - cpu_emergency_vmxoff(); - cpu_emergency_svm_disable(); -} - #if defined(CONFIG_SMP) static nmi_shootdown_cb shootdown_callback; |