1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/cpuhotplug.h>
4 #include <linux/cpumask.h>
5 #include <linux/slab.h>
6 #include <linux/mm.h>
7 
8 #include <asm/apic.h>
9 
10 #include "local.h"
11 
12 struct cluster_mask {
13 	unsigned int	clusterid;
14 	int		node;
15 	struct cpumask	mask;
16 };
17 
18 static DEFINE_PER_CPU(u32, x86_cpu_to_logical_apicid);
19 static DEFINE_PER_CPU(cpumask_var_t, ipi_mask);
20 static DEFINE_PER_CPU(struct cluster_mask *, cluster_masks);
21 static struct cluster_mask *cluster_hotplug_mask;
22 
23 static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
24 {
25 	return x2apic_enabled();
26 }
27 
28 static void x2apic_send_IPI(int cpu, int vector)
29 {
30 	u32 dest = per_cpu(x86_cpu_to_logical_apicid, cpu);
31 
32 	/* x2apic MSRs are special and need a special fence: */
33 	weak_wrmsr_fence();
34 	__x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL);
35 }
36 
37 static void
38 __x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest)
39 {
40 	unsigned int cpu, clustercpu;
41 	struct cpumask *tmpmsk;
42 	unsigned long flags;
43 	u32 dest;
44 
45 	/* x2apic MSRs are special and need a special fence: */
46 	weak_wrmsr_fence();
47 	local_irq_save(flags);
48 
49 	tmpmsk = this_cpu_cpumask_var_ptr(ipi_mask);
50 	cpumask_copy(tmpmsk, mask);
51 	/* If IPI should not be sent to self, clear current CPU */
52 	if (apic_dest != APIC_DEST_ALLINC)
53 		__cpumask_clear_cpu(smp_processor_id(), tmpmsk);
54 
55 	/* Collapse cpus in a cluster so a single IPI per cluster is sent */
56 	for_each_cpu(cpu, tmpmsk) {
57 		struct cluster_mask *cmsk = per_cpu(cluster_masks, cpu);
58 
59 		dest = 0;
60 		for_each_cpu_and(clustercpu, tmpmsk, &cmsk->mask)
61 			dest |= per_cpu(x86_cpu_to_logical_apicid, clustercpu);
62 
63 		if (!dest)
64 			continue;
65 
66 		__x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL);
67 		/* Remove cluster CPUs from tmpmask */
68 		cpumask_andnot(tmpmsk, tmpmsk, &cmsk->mask);
69 	}
70 
71 	local_irq_restore(flags);
72 }
73 
74 static void x2apic_send_IPI_mask(const struct cpumask *mask, int vector)
75 {
76 	__x2apic_send_IPI_mask(mask, vector, APIC_DEST_ALLINC);
77 }
78 
79 static void
80 x2apic_send_IPI_mask_allbutself(const struct cpumask *mask, int vector)
81 {
82 	__x2apic_send_IPI_mask(mask, vector, APIC_DEST_ALLBUT);
83 }
84 
85 static void x2apic_send_IPI_allbutself(int vector)
86 {
87 	__x2apic_send_IPI_shorthand(vector, APIC_DEST_ALLBUT);
88 }
89 
90 static void x2apic_send_IPI_all(int vector)
91 {
92 	__x2apic_send_IPI_shorthand(vector, APIC_DEST_ALLINC);
93 }
94 
95 static u32 x2apic_calc_apicid(unsigned int cpu)
96 {
97 	return per_cpu(x86_cpu_to_logical_apicid, cpu);
98 }
99 
100 static void init_x2apic_ldr(void)
101 {
102 	struct cluster_mask *cmsk = this_cpu_read(cluster_masks);
103 	u32 cluster, apicid = apic_read(APIC_LDR);
104 	unsigned int cpu;
105 
106 	this_cpu_write(x86_cpu_to_logical_apicid, apicid);
107 
108 	if (cmsk)
109 		goto update;
110 
111 	cluster = apicid >> 16;
112 	for_each_online_cpu(cpu) {
113 		cmsk = per_cpu(cluster_masks, cpu);
114 		/* Matching cluster found. Link and update it. */
115 		if (cmsk && cmsk->clusterid == cluster)
116 			goto update;
117 	}
118 	cmsk = cluster_hotplug_mask;
119 	cmsk->clusterid = cluster;
120 	cluster_hotplug_mask = NULL;
121 update:
122 	this_cpu_write(cluster_masks, cmsk);
123 	cpumask_set_cpu(smp_processor_id(), &cmsk->mask);
124 }
125 
126 static int alloc_clustermask(unsigned int cpu, int node)
127 {
128 	if (per_cpu(cluster_masks, cpu))
129 		return 0;
130 	/*
131 	 * If a hotplug spare mask exists, check whether it's on the right
132 	 * node. If not, free it and allocate a new one.
133 	 */
134 	if (cluster_hotplug_mask) {
135 		if (cluster_hotplug_mask->node == node)
136 			return 0;
137 		kfree(cluster_hotplug_mask);
138 	}
139 
140 	cluster_hotplug_mask = kzalloc_node(sizeof(*cluster_hotplug_mask),
141 					    GFP_KERNEL, node);
142 	if (!cluster_hotplug_mask)
143 		return -ENOMEM;
144 	cluster_hotplug_mask->node = node;
145 	return 0;
146 }
147 
148 static int x2apic_prepare_cpu(unsigned int cpu)
149 {
150 	if (alloc_clustermask(cpu, cpu_to_node(cpu)) < 0)
151 		return -ENOMEM;
152 	if (!zalloc_cpumask_var(&per_cpu(ipi_mask, cpu), GFP_KERNEL))
153 		return -ENOMEM;
154 	return 0;
155 }
156 
157 static int x2apic_dead_cpu(unsigned int dead_cpu)
158 {
159 	struct cluster_mask *cmsk = per_cpu(cluster_masks, dead_cpu);
160 
161 	if (cmsk)
162 		cpumask_clear_cpu(dead_cpu, &cmsk->mask);
163 	free_cpumask_var(per_cpu(ipi_mask, dead_cpu));
164 	return 0;
165 }
166 
167 static int x2apic_cluster_probe(void)
168 {
169 	if (!x2apic_mode)
170 		return 0;
171 
172 	if (cpuhp_setup_state(CPUHP_X2APIC_PREPARE, "x86/x2apic:prepare",
173 			      x2apic_prepare_cpu, x2apic_dead_cpu) < 0) {
174 		pr_err("Failed to register X2APIC_PREPARE\n");
175 		return 0;
176 	}
177 	init_x2apic_ldr();
178 	return 1;
179 }
180 
181 static struct apic apic_x2apic_cluster __ro_after_init = {
182 
183 	.name				= "cluster x2apic",
184 	.probe				= x2apic_cluster_probe,
185 	.acpi_madt_oem_check		= x2apic_acpi_madt_oem_check,
186 	.apic_id_valid			= x2apic_apic_id_valid,
187 	.apic_id_registered		= x2apic_apic_id_registered,
188 
189 	.delivery_mode			= APIC_DELIVERY_MODE_FIXED,
190 	.dest_mode_logical		= true,
191 
192 	.disable_esr			= 0,
193 
194 	.check_apicid_used		= NULL,
195 	.init_apic_ldr			= init_x2apic_ldr,
196 	.ioapic_phys_id_map		= NULL,
197 	.setup_apic_routing		= NULL,
198 	.cpu_present_to_apicid		= default_cpu_present_to_apicid,
199 	.apicid_to_cpu_present		= NULL,
200 	.check_phys_apicid_present	= default_check_phys_apicid_present,
201 	.phys_pkg_id			= x2apic_phys_pkg_id,
202 
203 	.get_apic_id			= x2apic_get_apic_id,
204 	.set_apic_id			= x2apic_set_apic_id,
205 
206 	.calc_dest_apicid		= x2apic_calc_apicid,
207 
208 	.send_IPI			= x2apic_send_IPI,
209 	.send_IPI_mask			= x2apic_send_IPI_mask,
210 	.send_IPI_mask_allbutself	= x2apic_send_IPI_mask_allbutself,
211 	.send_IPI_allbutself		= x2apic_send_IPI_allbutself,
212 	.send_IPI_all			= x2apic_send_IPI_all,
213 	.send_IPI_self			= x2apic_send_IPI_self,
214 
215 	.inquire_remote_apic		= NULL,
216 
217 	.read				= native_apic_msr_read,
218 	.write				= native_apic_msr_write,
219 	.eoi_write			= native_apic_msr_eoi_write,
220 	.icr_read			= native_x2apic_icr_read,
221 	.icr_write			= native_x2apic_icr_write,
222 	.wait_icr_idle			= native_x2apic_wait_icr_idle,
223 	.safe_wait_icr_idle		= native_safe_x2apic_wait_icr_idle,
224 };
225 
226 apic_driver(apic_x2apic_cluster);
227