x86, hotplug: Wake up CPU0 via NMI instead of INIT, SIPI, SIPI (e1c467e6) · Commits · 戴 / test

arch/x86/include/asm/cpu.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -28,6 +28,7 @@ struct x86_cpu {
		#ifdef CONFIG_HOTPLUG_CPU
		extern int arch_register_cpu(int num);
		extern void arch_unregister_cpu(int);
		extern void __cpuinit start_cpu0(void);
		#endif

		DECLARE_PER_CPU(int, cpu_state);

arch/x86/kernel/smpboot.c

+104 −7

Original line number	Diff line number	Diff line
		@@ -138,15 +138,17 @@ static void __cpuinit smp_callin(void)
		* we may get here before an INIT-deassert IPI reaches
		* our local APIC. We have to wait for the IPI or we'll
		* lock up on an APIC access.
		*
		* Since CPU0 is not wakened up by INIT, it doesn't wait for the IPI.
		*/
		if (apic->wait_for_init_deassert)
		cpuid = smp_processor_id();
		if (apic->wait_for_init_deassert && cpuid != 0)
		apic->wait_for_init_deassert(&init_deasserted);

		/*
		* (This works even if the APIC is not enabled.)
		*/
		phys_id = read_apic_id();
		cpuid = smp_processor_id();
		if (cpumask_test_cpu(cpuid, cpu_callin_mask)) {
		panic("%s: phys CPU#%d, CPU#%d already present??\n", __func__,
		phys_id, cpuid);
		@@ -228,6 +230,8 @@ static void __cpuinit smp_callin(void)
		cpumask_set_cpu(cpuid, cpu_callin_mask);
		}

		static int cpu0_logical_apicid;
		static int enable_start_cpu0;
		/*
		* Activate a secondary processor.
		*/
		@@ -243,6 +247,8 @@ notrace static void __cpuinit start_secondary(void *unused)
		preempt_disable();
		smp_callin();

		enable_start_cpu0 = 0;

		#ifdef CONFIG_X86_32
		/* switch away from the initial page table */
		load_cr3(swapper_pg_dir);
		@@ -492,7 +498,7 @@ void __inquire_remote_apic(int apicid)
		* won't ... remember to clear down the APIC, etc later.
		*/
		int __cpuinit
		wakeup_secondary_cpu_via_nmi(int logical_apicid, unsigned long start_eip)
		wakeup_secondary_cpu_via_nmi(int apicid, unsigned long start_eip)
		{
		unsigned long send_status, accept_status = 0;
		int maxlvt;
		@@ -500,7 +506,7 @@ wakeup_secondary_cpu_via_nmi(int logical_apicid, unsigned long start_eip)
		/* Target chip */
		/* Boot on the stack */
		/* Kick the second */
		apic_icr_write(APIC_DM_NMI \| apic->dest_logical, logical_apicid);
		apic_icr_write(APIC_DM_NMI \| apic->dest_logical, apicid);

		pr_debug("Waiting for send to finish...\n");
		send_status = safe_apic_wait_icr_idle();
		@@ -660,6 +666,63 @@ static void __cpuinit announce_cpu(int cpu, int apicid)
		node, cpu, apicid);
		}

		static int wakeup_cpu0_nmi(unsigned int cmd, struct pt_regs *regs)
		{
		int cpu;

		cpu = smp_processor_id();
		if (cpu == 0 && !cpu_online(cpu) && enable_start_cpu0)
		return NMI_HANDLED;

		return NMI_DONE;
		}

		/*
		* Wake up AP by INIT, INIT, STARTUP sequence.
		*
		* Instead of waiting for STARTUP after INITs, BSP will execute the BIOS
		* boot-strap code which is not a desired behavior for waking up BSP. To
		* void the boot-strap code, wake up CPU0 by NMI instead.
		*
		* This works to wake up soft offlined CPU0 only. If CPU0 is hard offlined
		* (i.e. physically hot removed and then hot added), NMI won't wake it up.
		* We'll change this code in the future to wake up hard offlined CPU0 if
		* real platform and request are available.
		*/
		static int __cpuinit
		wakeup_cpu_via_init_nmi(int cpu, unsigned long start_ip, int apicid,
		int *cpu0_nmi_registered)
		{
		int id;
		int boot_error;

		/*
		* Wake up AP by INIT, INIT, STARTUP sequence.
		*/
		if (cpu)
		return wakeup_secondary_cpu_via_init(apicid, start_ip);

		/*
		* Wake up BSP by nmi.
		*
		* Register a NMI handler to help wake up CPU0.
		*/
		boot_error = register_nmi_handler(NMI_LOCAL,
		wakeup_cpu0_nmi, 0, "wake_cpu0");

		if (!boot_error) {
		enable_start_cpu0 = 1;
		*cpu0_nmi_registered = 1;
		if (apic->dest_logical == APIC_DEST_LOGICAL)
		id = cpu0_logical_apicid;
		else
		id = apicid;
		boot_error = wakeup_secondary_cpu_via_nmi(id, start_ip);
		}

		return boot_error;
		}

		/*
		* NOTE - on most systems this is a PHYSICAL apic ID, but on multiquad
		* (ie clustered apic addressing mode), this is a LOGICAL apic ID.
		@@ -675,6 +738,7 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu, struct task_struct *idle)

		unsigned long boot_error = 0;
		int timeout;
		int cpu0_nmi_registered = 0;

		/* Just in case we booted with a single CPU. */
		alternatives_enable_smp();
		@@ -722,13 +786,16 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
		}

		/*
		* Kick the secondary CPU. Use the method in the APIC driver
		* if it's defined - or use an INIT boot APIC message otherwise:
		* Wake up a CPU in difference cases:
		* - Use the method in the APIC driver if it's defined
		* Otherwise,
		* - Use an INIT boot APIC message for APs or NMI for BSP.
		*/
		if (apic->wakeup_secondary_cpu)
		boot_error = apic->wakeup_secondary_cpu(apicid, start_ip);
		else
		boot_error = wakeup_secondary_cpu_via_init(apicid, start_ip);
		boot_error = wakeup_cpu_via_init_nmi(cpu, start_ip, apicid,
		&cpu0_nmi_registered);

		if (!boot_error) {
		/*
		@@ -793,6 +860,13 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
		*/
		smpboot_restore_warm_reset_vector();
		}
		/*
		* Clean up the nmi handler. Do this after the callin and callout sync
		* to avoid impact of possible long unregister time.
		*/
		if (cpu0_nmi_registered)
		unregister_nmi_handler(NMI_LOCAL, "wake_cpu0");

		return boot_error;
		}

		@@ -1037,6 +1111,11 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
		*/
		setup_local_APIC();

		if (x2apic_mode)
		cpu0_logical_apicid = apic_read(APIC_LDR);
		else
		cpu0_logical_apicid = GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));

		/*
		* Enable IO APIC before setting up error vector
		*/
		@@ -1264,6 +1343,14 @@ void play_dead_common(void)
		local_irq_disable();
		}

		static bool wakeup_cpu0(void)
		{
		if (smp_processor_id() == 0 && enable_start_cpu0)
		return true;

		return false;
		}

		/*
		* We need to flush the caches before going to sleep, lest we have
		* dirty data in our caches when we come back up.
		@@ -1327,6 +1414,11 @@ static inline void mwait_play_dead(void)
		__monitor(mwait_ptr, 0, 0);
		mb();
		__mwait(eax, 0);
		/*
		* If NMI wants to wake up CPU0, start CPU0.
		*/
		if (wakeup_cpu0())
		start_cpu0();
		}
		}

		@@ -1337,6 +1429,11 @@ static inline void hlt_play_dead(void)

		while (1) {
		native_halt();
		/*
		* If NMI wants to wake up CPU0, start CPU0.
		*/
		if (wakeup_cpu0())
		start_cpu0();
		}
		}

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