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 
default_get_apic_id(u32 x)21 static 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. */
probe_default(void)32 static int probe_default(void)
33 {
34 	return 1;
35 }
36 
37 static 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 
70 apic_driver(apic_default);
71 
72 struct apic *apic __ro_after_init = &apic_default;
73 EXPORT_SYMBOL_GPL(apic);
74 
75 static int cmdline_apic __initdata;
parse_apic(char * arg)76 static 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 }
94 early_param("apic", parse_apic);
95 
x86_32_probe_bigsmp_early(void)96 void __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 
x86_32_install_bigsmp(void)119 void __init x86_32_install_bigsmp(void)
120 {
121 	if (nr_cpu_ids > 8 && !xen_pv_domain())
122 		apic_bigsmp_force();
123 }
124 
x86_32_probe_apic(void)125 void __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