freeze: allow interrupts in frozen state

Change-Id: I1d502f828ab9f9c0e1223d021979ac3dcf4d0c25

arch/arm64/kernel/cpu.c

@@ -796,6 +796,21 @@ unsigned long cpu_disable_interrupt_save(void)
 	return flags;
 }
 
+/* save ICC_PMR_EL1 & enable interrupt (ICC_PMR_EL1 <= ICC_PMR_EL1_UNMASKED) */
+unsigned long cpu_enable_interrupt_save(void)
+{
+	unsigned long flags;
+	unsigned long masked = ICC_PMR_EL1_UNMASKED;
+
+	asm volatile(
+		"mrs_s  %0, " __stringify(ICC_PMR_EL1) "\n"
+		"msr_s  " __stringify(ICC_PMR_EL1) ",%1"
+		: "=&r" (flags)
+		: "r" (masked)
+		: "memory");
+	return flags;
+}
+
 #else /* defined(CONFIG_HAS_NMI) */
 
 /* @ref.impl arch/arm64/include/asm/irqflags.h::arch_local_irq_enable */
@@ -844,6 +859,20 @@ unsigned long cpu_disable_interrupt_save(void)
 		: "memory");
 	return flags;
 }
+
+/* save PSTATE.DAIF & enable interrupt (PSTATE.DAIF I bit set) */
+unsigned long cpu_enable_interrupt_save(void)
+{
+	unsigned long flags;
+
+	asm volatile(
+		"mrs    %0, daif	// arch_local_irq_save\n"
+		"msr    daifclr, #2"
+		: "=r" (flags)
+		:
+		: "memory");
+	return flags;
+}
 #endif /* defined(CONFIG_HAS_NMI) */
 
 /* we not have "pause" instruction, instead "yield" instruction */

arch/x86_64/kernel/cpu.c

@@ -1203,6 +1203,15 @@ unsigned long cpu_disable_interrupt_save(void)
 	return flags;
 }
 
+unsigned long cpu_enable_interrupt_save(void)
+{
+	unsigned long flags;
+
+	asm volatile("pushf; pop %0; sti" : "=r"(flags) : : "memory", "cc");
+
+	return flags;
+}
+
 /*@
   @ behavior valid_vector:
   @   assumes 32 <= vector <= 255;

kernel/freeze.c

@@ -14,14 +14,17 @@ extern void __freeze();
 void
 freeze()
 {
+	unsigned long flags;
 	struct ihk_os_cpu_monitor *monitor = cpu_local_var(monitor);
 
 	monitor->status_bak = monitor->status;
 	monitor->status = IHK_OS_MONITOR_KERNEL_FROZEN;
+	flags = cpu_enable_interrupt_save();
 	while (monitor->status == IHK_OS_MONITOR_KERNEL_FROZEN) {
 		cpu_halt();
 		cpu_pause();
 	}
+	cpu_restore_interrupt(flags);
 	monitor->status = monitor->status_bak;
 }
 

lib/include/ihk/cpu.h

@@ -9,7 +9,7 @@
 /*
  * HISTORY
  */
-/* cpu.h COPYRIGHT FUJITSU LIMITED 2015-2016 */
+/* cpu.h COPYRIGHT FUJITSU LIMITED 2015-2019 */
 
 #ifndef IHK_CPU_H
 #define IHK_CPU_H
@@ -28,6 +28,7 @@ void cpu_restore_interrupt(unsigned long);
 void cpu_pause(void);
 
 unsigned long cpu_disable_interrupt_save(void);
+unsigned long cpu_enable_interrupt_save(void);
 
 struct ihk_mc_interrupt_handler {
 	struct list_head list;