1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Default generic APIC driver. This handles up to 8 CPUs.
4 *
5 * Copyright 2003 Andi Kleen, SuSE Labs.
6 *
7 * Generic x86 APIC driver probe layer.
8 */
9#include <linux/export.h>
10#include <linux/errno.h>
11#include <linux/smp.h>
12
13#include <xen/xen.h>
14
15#include <asm/io_apic.h>
16#include <asm/apic.h>
17#include <asm/acpi.h>
18
19#include "local.h"
20
21static u32 default_get_apic_id(u32 x)
22{
23	unsigned int ver = GET_APIC_VERSION(apic_read(APIC_LVR));
24
25	if (APIC_XAPIC(ver) || boot_cpu_has(X86_FEATURE_EXTD_APICID))
26		return (x >> 24) & 0xFF;
27	else
28		return (x >> 24) & 0x0F;
29}
30
31/* should be called last. */
32static int probe_default(void)
33{
34	return 1;
35}
36
37static struct apic apic_default __ro_after_init = {
38
39	.name				= "default",
40	.probe				= probe_default,
41
42	.dest_mode_logical		= true,
43
44	.disable_esr			= 0,
45
46	.init_apic_ldr			= default_init_apic_ldr,
47	.cpu_present_to_apicid		= default_cpu_present_to_apicid,
48
49	.max_apic_id			= 0xFE,
50	.get_apic_id			= default_get_apic_id,
51
52	.calc_dest_apicid		= apic_flat_calc_apicid,
53
54	.send_IPI			= default_send_IPI_single,
55	.send_IPI_mask			= default_send_IPI_mask_logical,
56	.send_IPI_mask_allbutself	= default_send_IPI_mask_allbutself_logical,
57	.send_IPI_allbutself		= default_send_IPI_allbutself,
58	.send_IPI_all			= default_send_IPI_all,
59	.send_IPI_self			= default_send_IPI_self,
60
61	.read				= native_apic_mem_read,
62	.write				= native_apic_mem_write,
63	.eoi				= native_apic_mem_eoi,
64	.icr_read			= native_apic_icr_read,
65	.icr_write			= native_apic_icr_write,
66	.wait_icr_idle			= apic_mem_wait_icr_idle,
67	.safe_wait_icr_idle		= apic_mem_wait_icr_idle_timeout,
68};
69
70apic_driver(apic_default);
71
72struct apic *apic __ro_after_init = &apic_default;
73EXPORT_SYMBOL_GPL(apic);
74
75static int cmdline_apic __initdata;
76static int __init parse_apic(char *arg)
77{
78	struct apic **drv;
79
80	if (!arg)
81		return -EINVAL;
82
83	for (drv = __apicdrivers; drv < __apicdrivers_end; drv++) {
84		if (!strcmp((*drv)->name, arg)) {
85			apic_install_driver(*drv);
86			cmdline_apic = 1;
87			return 0;
88		}
89	}
90
91	/* Parsed again by __setup for debug/verbose */
92	return 0;
93}
94early_param("apic", parse_apic);
95
96void __init x86_32_probe_bigsmp_early(void)
97{
98	if (nr_cpu_ids <= 8 || xen_pv_domain())
99		return;
100
101	if (IS_ENABLED(CONFIG_X86_BIGSMP)) {
102		switch (boot_cpu_data.x86_vendor) {
103		case X86_VENDOR_INTEL:
104			if (!APIC_XAPIC(boot_cpu_apic_version))
105				break;
106			/* P4 and above */
107			fallthrough;
108		case X86_VENDOR_HYGON:
109		case X86_VENDOR_AMD:
110			if (apic_bigsmp_possible(cmdline_apic))
111				return;
112			break;
113		}
114	}
115	pr_info("Limiting to 8 possible CPUs\n");
116	set_nr_cpu_ids(8);
117}
118
119void __init x86_32_install_bigsmp(void)
120{
121	if (nr_cpu_ids > 8 && !xen_pv_domain())
122		apic_bigsmp_force();
123}
124
125void __init x86_32_probe_apic(void)
126{
127	if (!cmdline_apic) {
128		struct apic **drv;
129
130		for (drv = __apicdrivers; drv < __apicdrivers_end; drv++) {
131			if ((*drv)->probe()) {
132				apic_install_driver(*drv);
133				break;
134			}
135		}
136		/* Not visible without early console */
137		if (drv == __apicdrivers_end)
138			panic("Didn't find an APIC driver");
139	}
140}
141