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 /*
19  * __x2apic_send_IPI_mask() possibly needs to read
20  * x86_cpu_to_logical_apicid for all online cpus in a sequential way.
21  * Using per cpu variable would cost one cache line per cpu.
22  */
23 static u32 *x86_cpu_to_logical_apicid __read_mostly;
24 
25 static DEFINE_PER_CPU(cpumask_var_t, ipi_mask);
26 static DEFINE_PER_CPU_READ_MOSTLY(struct cluster_mask *, cluster_masks);
27 static struct cluster_mask *cluster_hotplug_mask;
28 
x2apic_acpi_madt_oem_check(char * oem_id,char * oem_table_id)29 static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
30 {
31 	return x2apic_enabled();
32 }
33 
x2apic_send_IPI(int cpu,int vector)34 static void x2apic_send_IPI(int cpu, int vector)
35 {
36 	u32 dest = x86_cpu_to_logical_apicid[cpu];
37 
38 	/* x2apic MSRs are special and need a special fence: */
39 	weak_wrmsr_fence();
40 	__x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL);
41 }
42 
43 static void
__x2apic_send_IPI_mask(const struct cpumask * mask,int vector,int apic_dest)44 __x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest)
45 {
46 	unsigned int cpu, clustercpu;
47 	struct cpumask *tmpmsk;
48 	unsigned long flags;
49 	u32 dest;
50 
51 	/* x2apic MSRs are special and need a special fence: */
52 	weak_wrmsr_fence();
53 	local_irq_save(flags);
54 
55 	tmpmsk = this_cpu_cpumask_var_ptr(ipi_mask);
56 	cpumask_copy(tmpmsk, mask);
57 	/* If IPI should not be sent to self, clear current CPU */
58 	if (apic_dest != APIC_DEST_ALLINC)
59 		__cpumask_clear_cpu(smp_processor_id(), tmpmsk);
60 
61 	/* Collapse cpus in a cluster so a single IPI per cluster is sent */
62 	for_each_cpu(cpu, tmpmsk) {
63 		struct cluster_mask *cmsk = per_cpu(cluster_masks, cpu);
64 
65 		dest = 0;
66 		for_each_cpu_and(clustercpu, tmpmsk, &cmsk->mask)
67 			dest |= x86_cpu_to_logical_apicid[clustercpu];
68 
69 		if (!dest)
70 			continue;
71 
72 		__x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL);
73 		/* Remove cluster CPUs from tmpmask */
74 		cpumask_andnot(tmpmsk, tmpmsk, &cmsk->mask);
75 	}
76 
77 	local_irq_restore(flags);
78 }
79 
x2apic_send_IPI_mask(const struct cpumask * mask,int vector)80 static void x2apic_send_IPI_mask(const struct cpumask *mask, int vector)
81 {
82 	__x2apic_send_IPI_mask(mask, vector, APIC_DEST_ALLINC);
83 }
84 
85 static void
x2apic_send_IPI_mask_allbutself(const struct cpumask * mask,int vector)86 x2apic_send_IPI_mask_allbutself(const struct cpumask *mask, int vector)
87 {
88 	__x2apic_send_IPI_mask(mask, vector, APIC_DEST_ALLBUT);
89 }
90 
x2apic_send_IPI_allbutself(int vector)91 static void x2apic_send_IPI_allbutself(int vector)
92 {
93 	__x2apic_send_IPI_shorthand(vector, APIC_DEST_ALLBUT);
94 }
95 
x2apic_send_IPI_all(int vector)96 static void x2apic_send_IPI_all(int vector)
97 {
98 	__x2apic_send_IPI_shorthand(vector, APIC_DEST_ALLINC);
99 }
100 
x2apic_calc_apicid(unsigned int cpu)101 static u32 x2apic_calc_apicid(unsigned int cpu)
102 {
103 	return x86_cpu_to_logical_apicid[cpu];
104 }
105 
init_x2apic_ldr(void)106 static void init_x2apic_ldr(void)
107 {
108 	struct cluster_mask *cmsk = this_cpu_read(cluster_masks);
109 	u32 cluster, apicid = apic_read(APIC_LDR);
110 	unsigned int cpu;
111 
112 	x86_cpu_to_logical_apicid[smp_processor_id()] = apicid;
113 
114 	if (cmsk)
115 		goto update;
116 
117 	cluster = apicid >> 16;
118 	for_each_online_cpu(cpu) {
119 		cmsk = per_cpu(cluster_masks, cpu);
120 		/* Matching cluster found. Link and update it. */
121 		if (cmsk && cmsk->clusterid == cluster)
122 			goto update;
123 	}
124 	cmsk = cluster_hotplug_mask;
125 	cmsk->clusterid = cluster;
126 	cluster_hotplug_mask = NULL;
127 update:
128 	this_cpu_write(cluster_masks, cmsk);
129 	cpumask_set_cpu(smp_processor_id(), &cmsk->mask);
130 }
131 
alloc_clustermask(unsigned int cpu,int node)132 static int alloc_clustermask(unsigned int cpu, int node)
133 {
134 	if (per_cpu(cluster_masks, cpu))
135 		return 0;
136 	/*
137 	 * If a hotplug spare mask exists, check whether it's on the right
138 	 * node. If not, free it and allocate a new one.
139 	 */
140 	if (cluster_hotplug_mask) {
141 		if (cluster_hotplug_mask->node == node)
142 			return 0;
143 		kfree(cluster_hotplug_mask);
144 	}
145 
146 	cluster_hotplug_mask = kzalloc_node(sizeof(*cluster_hotplug_mask),
147 					    GFP_KERNEL, node);
148 	if (!cluster_hotplug_mask)
149 		return -ENOMEM;
150 	cluster_hotplug_mask->node = node;
151 	return 0;
152 }
153 
x2apic_prepare_cpu(unsigned int cpu)154 static int x2apic_prepare_cpu(unsigned int cpu)
155 {
156 	if (alloc_clustermask(cpu, cpu_to_node(cpu)) < 0)
157 		return -ENOMEM;
158 	if (!zalloc_cpumask_var(&per_cpu(ipi_mask, cpu), GFP_KERNEL))
159 		return -ENOMEM;
160 	return 0;
161 }
162 
x2apic_dead_cpu(unsigned int dead_cpu)163 static int x2apic_dead_cpu(unsigned int dead_cpu)
164 {
165 	struct cluster_mask *cmsk = per_cpu(cluster_masks, dead_cpu);
166 
167 	if (cmsk)
168 		cpumask_clear_cpu(dead_cpu, &cmsk->mask);
169 	free_cpumask_var(per_cpu(ipi_mask, dead_cpu));
170 	return 0;
171 }
172 
x2apic_cluster_probe(void)173 static int x2apic_cluster_probe(void)
174 {
175 	u32 slots;
176 
177 	if (!x2apic_mode)
178 		return 0;
179 
180 	slots = max_t(u32, L1_CACHE_BYTES/sizeof(u32), nr_cpu_ids);
181 	x86_cpu_to_logical_apicid = kcalloc(slots, sizeof(u32), GFP_KERNEL);
182 	if (!x86_cpu_to_logical_apicid)
183 		return 0;
184 
185 	if (cpuhp_setup_state(CPUHP_X2APIC_PREPARE, "x86/x2apic:prepare",
186 			      x2apic_prepare_cpu, x2apic_dead_cpu) < 0) {
187 		pr_err("Failed to register X2APIC_PREPARE\n");
188 		kfree(x86_cpu_to_logical_apicid);
189 		x86_cpu_to_logical_apicid = NULL;
190 		return 0;
191 	}
192 	init_x2apic_ldr();
193 	return 1;
194 }
195 
196 static struct apic apic_x2apic_cluster __ro_after_init = {
197 
198 	.name				= "cluster x2apic",
199 	.probe				= x2apic_cluster_probe,
200 	.acpi_madt_oem_check		= x2apic_acpi_madt_oem_check,
201 	.apic_id_valid			= x2apic_apic_id_valid,
202 	.apic_id_registered		= x2apic_apic_id_registered,
203 
204 	.delivery_mode			= APIC_DELIVERY_MODE_FIXED,
205 	.dest_mode_logical		= true,
206 
207 	.disable_esr			= 0,
208 
209 	.check_apicid_used		= NULL,
210 	.init_apic_ldr			= init_x2apic_ldr,
211 	.ioapic_phys_id_map		= NULL,
212 	.setup_apic_routing		= NULL,
213 	.cpu_present_to_apicid		= default_cpu_present_to_apicid,
214 	.apicid_to_cpu_present		= NULL,
215 	.check_phys_apicid_present	= default_check_phys_apicid_present,
216 	.phys_pkg_id			= x2apic_phys_pkg_id,
217 
218 	.get_apic_id			= x2apic_get_apic_id,
219 	.set_apic_id			= x2apic_set_apic_id,
220 
221 	.calc_dest_apicid		= x2apic_calc_apicid,
222 
223 	.send_IPI			= x2apic_send_IPI,
224 	.send_IPI_mask			= x2apic_send_IPI_mask,
225 	.send_IPI_mask_allbutself	= x2apic_send_IPI_mask_allbutself,
226 	.send_IPI_allbutself		= x2apic_send_IPI_allbutself,
227 	.send_IPI_all			= x2apic_send_IPI_all,
228 	.send_IPI_self			= x2apic_send_IPI_self,
229 
230 	.inquire_remote_apic		= NULL,
231 
232 	.read				= native_apic_msr_read,
233 	.write				= native_apic_msr_write,
234 	.eoi_write			= native_apic_msr_eoi_write,
235 	.icr_read			= native_x2apic_icr_read,
236 	.icr_write			= native_x2apic_icr_write,
237 	.wait_icr_idle			= native_x2apic_wait_icr_idle,
238 	.safe_wait_icr_idle		= native_safe_x2apic_wait_icr_idle,
239 };
240 
241 apic_driver(apic_x2apic_cluster);
242