Commit edc8deb0 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

x86/reboot: Hoist "disable virt" helpers above "emergency reboot" path 



Move the various "disable virtualization" helpers above the emergency
reboot path so that emergency_reboot_disable_virtualization() can be
stubbed out in a future patch if neither KVM_INTEL nor KVM_AMD is enabled,
i.e. if there is no in-tree user of CPU virtualization.

No functional change intended.

Reviewed-by: default avatarKai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20230721201859.2307736-7-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent ad93c1a7

arch/x86/kernel/reboot.c

+45 −45
Original line number Diff line number Diff line
@@ -530,6 +530,51 @@ static inline void kb_wait(void) 


static inline void nmi_shootdown_cpus_on_restart(void);



/* 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)

{

	local_irq_disable();
@@ -786,54 +831,9 @@ void machine_crash_shutdown(struct pt_regs *regs) 
}

#endif



/* 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);



/* 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_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();

}



#if defined(CONFIG_SMP)



static nmi_shootdown_cb shootdown_callback;