x86, apic: Explain show_lapic= in kernel parameters list

[mirror_ubuntu-focal-kernel.git] / arch / x86 / kernel / apic / apic_noop.c

/*
 * NOOP APIC driver.
 *
 * Does almost nothing and should be substituted by a real apic driver via
 * probe routine.
 *
 * Though in case if apic is disabled (for some reason) we try
 * to not uglify the caller's code and allow to call (some) apic routines
 * like self-ipi, etc... and issue a warning if an operation is not allowed
 */

#include <linux/threads.h>
#include <linux/cpumask.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <asm/fixmap.h>
#include <asm/mpspec.h>
#include <asm/apicdef.h>
#include <asm/apic.h>
#include <asm/setup.h>

#include <linux/smp.h>
#include <asm/ipi.h>

#include <linux/interrupt.h>
#include <asm/acpi.h>
#include <asm/e820.h>

/*
 * some operations should never be reached with
 * noop apic if it's not turned off, this mostly
 * means the caller forgot to disable apic (or
 * check the apic presence) before doing a call
 */
static void warn_apic_enabled(void)
{
	WARN_ONCE((cpu_has_apic || !disable_apic),
		"APIC: Called for NOOP operation with apic enabled\n");
}

/*
 * To check operations but do not bloat source code
 */
#define NOOP_FUNC(func)			func { warn_apic_enabled(); }
#define NOOP_FUNC_RET(func, ret)	func { warn_apic_enabled(); return ret; }

NOOP_FUNC(static void noop_init_apic_ldr(void))
NOOP_FUNC(static void noop_send_IPI_mask(const struct cpumask *cpumask, int vector))
NOOP_FUNC(static void noop_send_IPI_mask_allbutself(const struct cpumask *cpumask, int vector))
NOOP_FUNC(static void noop_send_IPI_allbutself(int vector))
NOOP_FUNC(static void noop_send_IPI_all(int vector))
NOOP_FUNC(static void noop_send_IPI_self(int vector))
NOOP_FUNC_RET(static int noop_wakeup_secondary_cpu(int apicid, unsigned long start_eip), -1)
NOOP_FUNC(static void noop_apic_write(u32 reg, u32 v))
NOOP_FUNC(void noop_apic_wait_icr_idle(void))
NOOP_FUNC_RET(static u32 noop_safe_apic_wait_icr_idle(void), 0)
NOOP_FUNC_RET(static u64 noop_apic_icr_read(void), 0)
NOOP_FUNC(static void noop_apic_icr_write(u32 low, u32 id))
NOOP_FUNC_RET(static physid_mask_t noop_ioapic_phys_id_map(physid_mask_t phys_map), phys_map)
NOOP_FUNC_RET(static int noop_cpu_to_logical_apicid(int cpu), 1)
NOOP_FUNC_RET(static int noop_default_phys_pkg_id(int cpuid_apic, int index_msb), 0)
NOOP_FUNC_RET(static unsigned int noop_get_apic_id(unsigned long x), 0)

static int noop_probe(void)
{
	/* should not ever be enabled this way */
	return 0;
}

static int noop_apic_id_registered(void)
{
	warn_apic_enabled();
	return physid_isset(read_apic_id(), phys_cpu_present_map);
}

static const struct cpumask *noop_target_cpus(void)
{
	warn_apic_enabled();

	/* only BSP here */
	return cpumask_of(0);
}

static unsigned long noop_check_apicid_used(physid_mask_t bitmap, int apicid)
{
	warn_apic_enabled();
	return physid_isset(apicid, bitmap);
}

static unsigned long noop_check_apicid_present(int bit)
{
	warn_apic_enabled();
	return physid_isset(bit, phys_cpu_present_map);
}

static void noop_vector_allocation_domain(int cpu, struct cpumask *retmask)
{
	warn_apic_enabled();
	if (cpu != 0)
		pr_warning("APIC: Vector allocated for non-BSP cpu\n");
	cpumask_clear(retmask);
	cpumask_set_cpu(cpu, retmask);
}

int noop_apicid_to_node(int logical_apicid)
{
	warn_apic_enabled();

	/* we're always on node 0 */
	return 0;
}

static u32 noop_apic_read(u32 reg)
{
	/*
	 * noop-read is always safe until we have
	 * non-disabled unit
	 */
	WARN_ON_ONCE((cpu_has_apic && !disable_apic));
	return 0;
}

struct apic apic_noop = {
	.name				= "noop",
	.probe				= noop_probe,
	.acpi_madt_oem_check		= NULL,

	.apic_id_registered		= noop_apic_id_registered,

	.irq_delivery_mode		= dest_LowestPrio,
	/* logical delivery broadcast to all CPUs: */
	.irq_dest_mode			= 1,

	.target_cpus			= noop_target_cpus,
	.disable_esr			= 0,
	.dest_logical			= APIC_DEST_LOGICAL,
	.check_apicid_used		= noop_check_apicid_used,
	.check_apicid_present		= noop_check_apicid_present,

	.vector_allocation_domain	= noop_vector_allocation_domain,
	.init_apic_ldr			= noop_init_apic_ldr,

	.ioapic_phys_id_map		= noop_ioapic_phys_id_map,
	.setup_apic_routing		= NULL,
	.multi_timer_check		= NULL,
	.apicid_to_node			= noop_apicid_to_node,

	.cpu_to_logical_apicid		= noop_cpu_to_logical_apicid,
	.cpu_present_to_apicid		= default_cpu_present_to_apicid,
	.apicid_to_cpu_present		= default_apicid_to_cpu_present,

	.setup_portio_remap		= NULL,
	.check_phys_apicid_present	= default_check_phys_apicid_present,
	.enable_apic_mode		= NULL,

	.phys_pkg_id			= noop_default_phys_pkg_id,

	.mps_oem_check			= NULL,

	.get_apic_id			= noop_get_apic_id,
	.set_apic_id			= NULL,
	.apic_id_mask			= 0x0F << 24,

	.cpu_mask_to_apicid		= default_cpu_mask_to_apicid,
	.cpu_mask_to_apicid_and		= default_cpu_mask_to_apicid_and,

	.send_IPI_mask			= noop_send_IPI_mask,
	.send_IPI_mask_allbutself	= noop_send_IPI_mask_allbutself,
	.send_IPI_allbutself		= noop_send_IPI_allbutself,
	.send_IPI_all			= noop_send_IPI_all,
	.send_IPI_self			= noop_send_IPI_self,

	.wakeup_secondary_cpu		= noop_wakeup_secondary_cpu,

	/* should be safe */
	.trampoline_phys_low		= DEFAULT_TRAMPOLINE_PHYS_LOW,
	.trampoline_phys_high		= DEFAULT_TRAMPOLINE_PHYS_HIGH,

	.wait_for_init_deassert		= NULL,

	.smp_callin_clear_local_apic	= NULL,
	.inquire_remote_apic		= NULL,

	.read				= noop_apic_read,
	.write				= noop_apic_write,
	.icr_read			= noop_apic_icr_read,
	.icr_write			= noop_apic_icr_write,
	.wait_icr_idle			= noop_apic_wait_icr_idle,
	.safe_wait_icr_idle		= noop_safe_apic_wait_icr_idle,
};