arch/x86/kernel/apic/ipi.c - linux/torvalds/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0

 #include <linux/cpumask.h>
 #include <linux/smp.h>

 #include "local.h"

 DEFINE_STATIC_KEY_FALSE(apic_use_ipi_shorthand);

 #ifdef CONFIG_SMP
 static int apic_ipi_shorthand_off __ro_after_init;

 static __init int apic_ipi_shorthand(char *str)
 {
 	get_option(&str, &apic_ipi_shorthand_off);
 	return 1;
 }
 __setup("no_ipi_broadcast=", apic_ipi_shorthand);

 static int __init print_ipi_mode(void)
 {
 	pr_info("IPI shorthand broadcast: %s\n",
 		apic_ipi_shorthand_off ? "disabled" : "enabled");
 	return 0;
 }
 late_initcall(print_ipi_mode);

 void apic_smt_update(void)
 {
 	/*
 	 * Do not switch to broadcast mode if:
 	 * - Disabled on the command line
 	 * - Only a single CPU is online
 	 * - Not all present CPUs have been at least booted once
 	 *
 	 * The latter is important as the local APIC might be in some
 	 * random state and a broadcast might cause havoc. That's
 	 * especially true for NMI broadcasting.
 	 */
 	if (apic_ipi_shorthand_off || num_online_cpus() == 1 ||
 	    !cpumask_equal(cpu_present_mask, &cpus_booted_once_mask)) {
 		static_branch_disable(&apic_use_ipi_shorthand);
 	} else {
 		static_branch_enable(&apic_use_ipi_shorthand);
 	}
 }

 void apic_send_IPI_allbutself(unsigned int vector)
 {
 	if (num_online_cpus() < 2)
 		return;

 	if (static_branch_likely(&apic_use_ipi_shorthand))
 		apic->send_IPI_allbutself(vector);
 	else
 		apic->send_IPI_mask_allbutself(cpu_online_mask, vector);
 }

 /*
  * Send a 'reschedule' IPI to another CPU. It goes straight through and
  * wastes no time serializing anything. Worst case is that we lose a
  * reschedule ...
  */
 void native_smp_send_reschedule(int cpu)
 {
 	if (unlikely(cpu_is_offline(cpu))) {
 		WARN(1, "sched: Unexpected reschedule of offline CPU#%d!\n", cpu);
 		return;
 	}
 	apic->send_IPI(cpu, RESCHEDULE_VECTOR);
 }

 void native_send_call_func_single_ipi(int cpu)
 {
 	apic->send_IPI(cpu, CALL_FUNCTION_SINGLE_VECTOR);
 }

 void native_send_call_func_ipi(const struct cpumask *mask)
 {
 	if (static_branch_likely(&apic_use_ipi_shorthand)) {
 		unsigned int cpu = smp_processor_id();

 		if (!cpumask_or_equal(mask, cpumask_of(cpu), cpu_online_mask))
 			goto sendmask;

 		if (cpumask_test_cpu(cpu, mask))
 			apic->send_IPI_all(CALL_FUNCTION_VECTOR);
 		else if (num_online_cpus() > 1)
 			apic->send_IPI_allbutself(CALL_FUNCTION_VECTOR);
 		return;
 	}

 sendmask:
 	apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
 }

 #endif /* CONFIG_SMP */

 static inline int __prepare_ICR2(unsigned int mask)
 {
 	return SET_APIC_DEST_FIELD(mask);
 }

 static inline void __xapic_wait_icr_idle(void)
 {
 	while (native_apic_mem_read(APIC_ICR) & APIC_ICR_BUSY)
 		cpu_relax();
 }

 void __default_send_IPI_shortcut(unsigned int shortcut, int vector)
 {
 	/*
 	 * Subtle. In the case of the 'never do double writes' workaround
 	 * we have to lock out interrupts to be safe.  As we don't care
 	 * of the value read we use an atomic rmw access to avoid costly
 	 * cli/sti.  Otherwise we use an even cheaper single atomic write
 	 * to the APIC.
 	 */
 	unsigned int cfg;

 	/*
 	 * Wait for idle.
 	 */
 	if (unlikely(vector == NMI_VECTOR))
 		safe_apic_wait_icr_idle();
 	else
 		__xapic_wait_icr_idle();

 	/*
 	 * No need to touch the target chip field. Also the destination
 	 * mode is ignored when a shorthand is used.
 	 */
 	cfg = __prepare_ICR(shortcut, vector, 0);

 	/*
 	 * Send the IPI. The write to APIC_ICR fires this off.
 	 */
 	native_apic_mem_write(APIC_ICR, cfg);
 }

 /*
  * This is used to send an IPI with no shorthand notation (the destination is
  * specified in bits 56 to 63 of the ICR).
  */
 void __default_send_IPI_dest_field(unsigned int mask, int vector, unsigned int dest)
 {
 	unsigned long cfg;

 	/*
 	 * Wait for idle.
 	 */
 	if (unlikely(vector == NMI_VECTOR))
 		safe_apic_wait_icr_idle();
 	else
 		__xapic_wait_icr_idle();

 	/*
 	 * prepare target chip field
 	 */
 	cfg = __prepare_ICR2(mask);
 	native_apic_mem_write(APIC_ICR2, cfg);

 	/*
 	 * program the ICR
 	 */
 	cfg = __prepare_ICR(0, vector, dest);

 	/*
 	 * Send the IPI. The write to APIC_ICR fires this off.
 	 */
 	native_apic_mem_write(APIC_ICR, cfg);
 }

 void default_send_IPI_single_phys(int cpu, int vector)
 {
 	unsigned long flags;

 	local_irq_save(flags);
 	__default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid, cpu),
 				      vector, APIC_DEST_PHYSICAL);
 	local_irq_restore(flags);
 }

 void default_send_IPI_mask_sequence_phys(const struct cpumask *mask, int vector)
 {
 	unsigned long query_cpu;
 	unsigned long flags;

 	/*
 	 * Hack. The clustered APIC addressing mode doesn't allow us to send
 	 * to an arbitrary mask, so I do a unicast to each CPU instead.
 	 * - mbligh
 	 */
 	local_irq_save(flags);
 	for_each_cpu(query_cpu, mask) {
 		__default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid,
 				query_cpu), vector, APIC_DEST_PHYSICAL);
 	}
 	local_irq_restore(flags);
 }

 void default_send_IPI_mask_allbutself_phys(const struct cpumask *mask,
 						 int vector)
 {
 	unsigned int this_cpu = smp_processor_id();
 	unsigned int query_cpu;
 	unsigned long flags;

 	/* See Hack comment above */

 	local_irq_save(flags);
 	for_each_cpu(query_cpu, mask) {
 		if (query_cpu == this_cpu)
 			continue;
 		__default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid,
 				 query_cpu), vector, APIC_DEST_PHYSICAL);
 	}
 	local_irq_restore(flags);
 }

 /*
  * Helper function for APICs which insist on cpumasks
  */
 void default_send_IPI_single(int cpu, int vector)
 {
 	apic->send_IPI_mask(cpumask_of(cpu), vector);
 }

 void default_send_IPI_allbutself(int vector)
 {
 	__default_send_IPI_shortcut(APIC_DEST_ALLBUT, vector);
 }

 void default_send_IPI_all(int vector)
 {
 	__default_send_IPI_shortcut(APIC_DEST_ALLINC, vector);
 }

 void default_send_IPI_self(int vector)
 {
 	__default_send_IPI_shortcut(APIC_DEST_SELF, vector);
 }

 #ifdef CONFIG_X86_32

 void default_send_IPI_mask_sequence_logical(const struct cpumask *mask,
 						 int vector)
 {
 	unsigned long flags;
 	unsigned int query_cpu;

 	/*
 	 * Hack. The clustered APIC addressing mode doesn't allow us to send
 	 * to an arbitrary mask, so I do a unicasts to each CPU instead. This
 	 * should be modified to do 1 message per cluster ID - mbligh
 	 */

 	local_irq_save(flags);
 	for_each_cpu(query_cpu, mask)
 		__default_send_IPI_dest_field(
 			early_per_cpu(x86_cpu_to_logical_apicid, query_cpu),
 			vector, apic->dest_logical);
 	local_irq_restore(flags);
 }

 void default_send_IPI_mask_allbutself_logical(const struct cpumask *mask,
 						 int vector)
 {
 	unsigned long flags;
 	unsigned int query_cpu;
 	unsigned int this_cpu = smp_processor_id();

 	/* See Hack comment above */

 	local_irq_save(flags);
 	for_each_cpu(query_cpu, mask) {
 		if (query_cpu == this_cpu)
 			continue;
 		__default_send_IPI_dest_field(
 			early_per_cpu(x86_cpu_to_logical_apicid, query_cpu),
 			vector, apic->dest_logical);
 		}
 	local_irq_restore(flags);
 }

 /*
  * This is only used on smaller machines.
  */
 void default_send_IPI_mask_logical(const struct cpumask *cpumask, int vector)
 {
 	unsigned long mask = cpumask_bits(cpumask)[0];
 	unsigned long flags;

 	if (!mask)
 		return;

 	local_irq_save(flags);
 	WARN_ON(mask & ~cpumask_bits(cpu_online_mask)[0]);
 	__default_send_IPI_dest_field(mask, vector, apic->dest_logical);
 	local_irq_restore(flags);
 }

 /* must come after the send_IPI functions above for inlining */
 static int convert_apicid_to_cpu(int apic_id)
 {
 	int i;

 	for_each_possible_cpu(i) {
 		if (per_cpu(x86_cpu_to_apicid, i) == apic_id)
 			return i;
 	}
 	return -1;
 }

 int safe_smp_processor_id(void)
 {
 	int apicid, cpuid;

 	if (!boot_cpu_has(X86_FEATURE_APIC))
 		return 0;

 	apicid = hard_smp_processor_id();
 	if (apicid == BAD_APICID)
 		return 0;

 	cpuid = convert_apicid_to_cpu(apicid);

 	return cpuid >= 0 ? cpuid : 0;
 }
 #endif
	// SPDX-License-Identifier: GPL-2.0

	#include <linux/cpumask.h>
	#include <linux/smp.h>

	#include "local.h"

	DEFINE_STATIC_KEY_FALSE(apic_use_ipi_shorthand);

	#ifdef CONFIG_SMP
	static int apic_ipi_shorthand_off __ro_after_init;

	static __init int apic_ipi_shorthand(char *str)
	{
	get_option(&str, &apic_ipi_shorthand_off);
	return 1;
	}
	__setup("no_ipi_broadcast=", apic_ipi_shorthand);

	static int __init print_ipi_mode(void)
	{
	pr_info("IPI shorthand broadcast: %s\n",
	apic_ipi_shorthand_off ? "disabled" : "enabled");
	return 0;
	}
	late_initcall(print_ipi_mode);

	void apic_smt_update(void)
	{
	/*
	* Do not switch to broadcast mode if:
	* - Disabled on the command line
	* - Only a single CPU is online
	* - Not all present CPUs have been at least booted once
	*
	* The latter is important as the local APIC might be in some
	* random state and a broadcast might cause havoc. That's
	* especially true for NMI broadcasting.
	*/
	if (apic_ipi_shorthand_off \|\| num_online_cpus() == 1 \|\|
	!cpumask_equal(cpu_present_mask, &cpus_booted_once_mask)) {
	static_branch_disable(&apic_use_ipi_shorthand);
	} else {
	static_branch_enable(&apic_use_ipi_shorthand);
	}
	}

	void apic_send_IPI_allbutself(unsigned int vector)
	{
	if (num_online_cpus() < 2)
	return;

	if (static_branch_likely(&apic_use_ipi_shorthand))
	apic->send_IPI_allbutself(vector);
	else
	apic->send_IPI_mask_allbutself(cpu_online_mask, vector);
	}

	/*
	* Send a 'reschedule' IPI to another CPU. It goes straight through and
	* wastes no time serializing anything. Worst case is that we lose a
	* reschedule ...
	*/
	void native_smp_send_reschedule(int cpu)
	{
	if (unlikely(cpu_is_offline(cpu))) {
	WARN(1, "sched: Unexpected reschedule of offline CPU#%d!\n", cpu);
	return;
	}
	apic->send_IPI(cpu, RESCHEDULE_VECTOR);
	}

	void native_send_call_func_single_ipi(int cpu)
	{
	apic->send_IPI(cpu, CALL_FUNCTION_SINGLE_VECTOR);
	}

	void native_send_call_func_ipi(const struct cpumask *mask)
	{
	if (static_branch_likely(&apic_use_ipi_shorthand)) {
	unsigned int cpu = smp_processor_id();

	if (!cpumask_or_equal(mask, cpumask_of(cpu), cpu_online_mask))
	goto sendmask;

	if (cpumask_test_cpu(cpu, mask))
	apic->send_IPI_all(CALL_FUNCTION_VECTOR);
	else if (num_online_cpus() > 1)
	apic->send_IPI_allbutself(CALL_FUNCTION_VECTOR);
	return;
	}

	sendmask:
	apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
	}

	#endif /* CONFIG_SMP */

	static inline int __prepare_ICR2(unsigned int mask)
	{
	return SET_APIC_DEST_FIELD(mask);
	}

	static inline void __xapic_wait_icr_idle(void)
	{
	while (native_apic_mem_read(APIC_ICR) & APIC_ICR_BUSY)
	cpu_relax();
	}

	void __default_send_IPI_shortcut(unsigned int shortcut, int vector)
	{
	/*
	* Subtle. In the case of the 'never do double writes' workaround
	* we have to lock out interrupts to be safe. As we don't care
	* of the value read we use an atomic rmw access to avoid costly
	* cli/sti. Otherwise we use an even cheaper single atomic write
	* to the APIC.
	*/
	unsigned int cfg;

	/*
	* Wait for idle.
	*/
	if (unlikely(vector == NMI_VECTOR))
	safe_apic_wait_icr_idle();
	else
	__xapic_wait_icr_idle();

	/*
	* No need to touch the target chip field. Also the destination
	* mode is ignored when a shorthand is used.
	*/
	cfg = __prepare_ICR(shortcut, vector, 0);

	/*
	* Send the IPI. The write to APIC_ICR fires this off.
	*/
	native_apic_mem_write(APIC_ICR, cfg);
	}

	/*
	* This is used to send an IPI with no shorthand notation (the destination is
	* specified in bits 56 to 63 of the ICR).
	*/
	void __default_send_IPI_dest_field(unsigned int mask, int vector, unsigned int dest)
	{
	unsigned long cfg;

	/*
	* Wait for idle.
	*/
	if (unlikely(vector == NMI_VECTOR))
	safe_apic_wait_icr_idle();
	else
	__xapic_wait_icr_idle();

	/*
	* prepare target chip field
	*/
	cfg = __prepare_ICR2(mask);
	native_apic_mem_write(APIC_ICR2, cfg);

	/*
	* program the ICR
	*/
	cfg = __prepare_ICR(0, vector, dest);

	/*
	* Send the IPI. The write to APIC_ICR fires this off.
	*/
	native_apic_mem_write(APIC_ICR, cfg);
	}

	void default_send_IPI_single_phys(int cpu, int vector)
	{
	unsigned long flags;

	local_irq_save(flags);
	__default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid, cpu),
	vector, APIC_DEST_PHYSICAL);
	local_irq_restore(flags);
	}

	void default_send_IPI_mask_sequence_phys(const struct cpumask *mask, int vector)
	{
	unsigned long query_cpu;
	unsigned long flags;

	/*
	* Hack. The clustered APIC addressing mode doesn't allow us to send
	* to an arbitrary mask, so I do a unicast to each CPU instead.
	* - mbligh
	*/
	local_irq_save(flags);
	for_each_cpu(query_cpu, mask) {
	__default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid,
	query_cpu), vector, APIC_DEST_PHYSICAL);
	}
	local_irq_restore(flags);
	}

	void default_send_IPI_mask_allbutself_phys(const struct cpumask *mask,
	int vector)
	{
	unsigned int this_cpu = smp_processor_id();
	unsigned int query_cpu;
	unsigned long flags;

	/* See Hack comment above */

	local_irq_save(flags);
	for_each_cpu(query_cpu, mask) {
	if (query_cpu == this_cpu)
	continue;
	__default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid,
	query_cpu), vector, APIC_DEST_PHYSICAL);
	}
	local_irq_restore(flags);
	}

	/*
	* Helper function for APICs which insist on cpumasks
	*/
	void default_send_IPI_single(int cpu, int vector)
	{
	apic->send_IPI_mask(cpumask_of(cpu), vector);
	}

	void default_send_IPI_allbutself(int vector)
	{
	__default_send_IPI_shortcut(APIC_DEST_ALLBUT, vector);
	}

	void default_send_IPI_all(int vector)
	{
	__default_send_IPI_shortcut(APIC_DEST_ALLINC, vector);
	}

	void default_send_IPI_self(int vector)
	{
	__default_send_IPI_shortcut(APIC_DEST_SELF, vector);
	}

	#ifdef CONFIG_X86_32

	void default_send_IPI_mask_sequence_logical(const struct cpumask *mask,
	int vector)
	{
	unsigned long flags;
	unsigned int query_cpu;

	/*
	* Hack. The clustered APIC addressing mode doesn't allow us to send
	* to an arbitrary mask, so I do a unicasts to each CPU instead. This
	* should be modified to do 1 message per cluster ID - mbligh
	*/

	local_irq_save(flags);
	for_each_cpu(query_cpu, mask)
	__default_send_IPI_dest_field(
	early_per_cpu(x86_cpu_to_logical_apicid, query_cpu),
	vector, apic->dest_logical);
	local_irq_restore(flags);
	}

	void default_send_IPI_mask_allbutself_logical(const struct cpumask *mask,
	int vector)
	{
	unsigned long flags;
	unsigned int query_cpu;
	unsigned int this_cpu = smp_processor_id();

	/* See Hack comment above */

	local_irq_save(flags);
	for_each_cpu(query_cpu, mask) {
	if (query_cpu == this_cpu)
	continue;
	__default_send_IPI_dest_field(
	early_per_cpu(x86_cpu_to_logical_apicid, query_cpu),
	vector, apic->dest_logical);
	}
	local_irq_restore(flags);
	}

	/*
	* This is only used on smaller machines.
	*/
	void default_send_IPI_mask_logical(const struct cpumask *cpumask, int vector)
	{
	unsigned long mask = cpumask_bits(cpumask)[0];
	unsigned long flags;

	if (!mask)
	return;

	local_irq_save(flags);
	WARN_ON(mask & ~cpumask_bits(cpu_online_mask)[0]);
	__default_send_IPI_dest_field(mask, vector, apic->dest_logical);
	local_irq_restore(flags);
	}

	/* must come after the send_IPI functions above for inlining */
	static int convert_apicid_to_cpu(int apic_id)
	{
	int i;

	for_each_possible_cpu(i) {
	if (per_cpu(x86_cpu_to_apicid, i) == apic_id)
	return i;
	}
	return -1;
	}

	int safe_smp_processor_id(void)
	{
	int apicid, cpuid;

	if (!boot_cpu_has(X86_FEATURE_APIC))
	return 0;

	apicid = hard_smp_processor_id();
	if (apicid == BAD_APICID)
	return 0;

	cpuid = convert_apicid_to_cpu(apicid);

	return cpuid >= 0 ? cpuid : 0;
	}
	#endif