x86_64: zero-init BSP and AP CPU cpu_data before use

arch/x86_64/acpi/smp.cpp

@@ -29,6 +29,7 @@ extern "C" void ap_trampoline_exit(void)
 	this_cpu->c_cpu_id = cpu_id;
 
 	struct cpu_data *self = get_this_cpu();
+	memset(self, 0x0, sizeof *self);
 	self->c_flags = CPU_ONLINE;
 	self->c_id = cpu_id;
 	this_cpu->c_data = self;

arch/x86_64/init.c

@@ -63,6 +63,8 @@ int ml_init(uintptr_t arg)
 	init_per_cpu_areas();
 
 	struct cpu_data *this_cpu = get_this_cpu();
+	memset(this_cpu, 0x0, sizeof *this_cpu);
+
 	this_cpu->c_flags = CPU_ONLINE;
 	this_cpu->c_id = this_cpu();
 	g_bootstrap_cpu.c_data = this_cpu;