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 #define apic_cluster(apicid) ((apicid) >> 4)
13
14 /*
15 * __x2apic_send_IPI_mask() possibly needs to read
16 * x86_cpu_to_logical_apicid for all online cpus in a sequential way.
17 * Using per cpu variable would cost one cache line per cpu.
18 */
19 static u32 *x86_cpu_to_logical_apicid __read_mostly;
20
21 static DEFINE_PER_CPU(cpumask_var_t, ipi_mask);
22 static DEFINE_PER_CPU_READ_MOSTLY(struct cpumask *, cluster_masks);
23
24 static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
25 {
26 return x2apic_enabled();
27 }
28
29 static void x2apic_send_IPI(int cpu, int vector)
30 {
31 u32 dest = x86_cpu_to_logical_apicid[cpu];
32
33 /* x2apic MSRs are special and need a special fence: */
34 weak_wrmsr_fence();
35 __x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL);
36 }
37
38 static void
39 __x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest)
40 {
41 unsigned int cpu, clustercpu;
42 struct cpumask *tmpmsk;
43 unsigned long flags;
44 u32 dest;
45
46 /* x2apic MSRs are special and need a special fence: */
47 weak_wrmsr_fence();
48 local_irq_save(flags);
49
50 tmpmsk = this_cpu_cpumask_var_ptr(ipi_mask);
51 cpumask_copy(tmpmsk, mask);
52 /* If IPI should not be sent to self, clear current CPU */
53 if (apic_dest != APIC_DEST_ALLINC)
54 __cpumask_clear_cpu(smp_processor_id(), tmpmsk);
55
56 /* Collapse cpus in a cluster so a single IPI per cluster is sent */
57 for_each_cpu(cpu, tmpmsk) {
58 struct cpumask *cmsk = per_cpu(cluster_masks, cpu);
59
60 dest = 0;
61 for_each_cpu_and(clustercpu, tmpmsk, cmsk)
62 dest |= x86_cpu_to_logical_apicid[clustercpu];
63
64 if (!dest)
65 continue;
66
67 __x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL);
68 /* Remove cluster CPUs from tmpmask */
69 cpumask_andnot(tmpmsk, tmpmsk, cmsk);
70 }
71
72 local_irq_restore(flags);
73 }
74
75 static void x2apic_send_IPI_mask(const struct cpumask *mask, int vector)
76 {
77 __x2apic_send_IPI_mask(mask, vector, APIC_DEST_ALLINC);
78 }
79
80 static void
81 x2apic_send_IPI_mask_allbutself(const struct cpumask *mask, int vector)
82 {
83 __x2apic_send_IPI_mask(mask, vector, APIC_DEST_ALLBUT);
84 }
85
86 static u32 x2apic_calc_apicid(unsigned int cpu)
87 {
88 return x86_cpu_to_logical_apicid[cpu];
89 }
90
91 static void init_x2apic_ldr(void)
92 {
93 struct cpumask *cmsk = this_cpu_read(cluster_masks);
94
95 BUG_ON(!cmsk);
96
97 cpumask_set_cpu(smp_processor_id(), cmsk);
98 }
99
100 /*
101 * As an optimisation during boot, set the cluster_mask for all present
102 * CPUs at once, to prevent each of them having to iterate over the others
103 * to find the existing cluster_mask.
104 */
105 static void prefill_clustermask(struct cpumask *cmsk, unsigned int cpu, u32 cluster)
106 {
107 int cpu_i;
108
109 for_each_present_cpu(cpu_i) {
110 struct cpumask **cpu_cmsk = &per_cpu(cluster_masks, cpu_i);
111 u32 apicid = apic->cpu_present_to_apicid(cpu_i);
112
113 if (apicid == BAD_APICID || cpu_i == cpu || apic_cluster(apicid) != cluster)
114 continue;
115
116 if (WARN_ON_ONCE(*cpu_cmsk == cmsk))
117 continue;
118
119 BUG_ON(*cpu_cmsk);
120 *cpu_cmsk = cmsk;
121 }
122 }
123
124 static int alloc_clustermask(unsigned int cpu, u32 cluster, int node)
125 {
126 struct cpumask *cmsk = NULL;
127 unsigned int cpu_i;
128
129 /*
130 * At boot time, the CPU present mask is stable. The cluster mask is
131 * allocated for the first CPU in the cluster and propagated to all
132 * present siblings in the cluster. If the cluster mask is already set
133 * on entry to this function for a given CPU, there is nothing to do.
134 */
135 if (per_cpu(cluster_masks, cpu))
136 return 0;
137
138 if (system_state < SYSTEM_RUNNING)
139 goto alloc;
140
141 /*
142 * On post boot hotplug for a CPU which was not present at boot time,
143 * iterate over all possible CPUs (even those which are not present
144 * any more) to find any existing cluster mask.
145 */
146 for_each_possible_cpu(cpu_i) {
147 u32 apicid = apic->cpu_present_to_apicid(cpu_i);
148
149 if (apicid != BAD_APICID && apic_cluster(apicid) == cluster) {
150 cmsk = per_cpu(cluster_masks, cpu_i);
151 /*
152 * If the cluster is already initialized, just store
153 * the mask and return. There's no need to propagate.
154 */
155 if (cmsk) {
156 per_cpu(cluster_masks, cpu) = cmsk;
157 return 0;
158 }
159 }
160 }
161 /*
162 * No CPU in the cluster has ever been initialized, so fall through to
163 * the boot time code which will also populate the cluster mask for any
164 * other CPU in the cluster which is (now) present.
165 */
166 alloc:
167 cmsk = kzalloc_node(sizeof(*cmsk), GFP_KERNEL, node);
168 if (!cmsk)
169 return -ENOMEM;
170 per_cpu(cluster_masks, cpu) = cmsk;
171 prefill_clustermask(cmsk, cpu, cluster);
172
173 return 0;
174 }
175
176 static int x2apic_prepare_cpu(unsigned int cpu)
177 {
178 u32 phys_apicid = apic->cpu_present_to_apicid(cpu);
179 u32 cluster = apic_cluster(phys_apicid);
180 u32 logical_apicid = (cluster << 16) | (1 << (phys_apicid & 0xf));
181 int node = cpu_to_node(cpu);
182
183 x86_cpu_to_logical_apicid[cpu] = logical_apicid;
184
185 if (alloc_clustermask(cpu, cluster, node) < 0)
186 return -ENOMEM;
187
188 if (!zalloc_cpumask_var_node(&per_cpu(ipi_mask, cpu), GFP_KERNEL, node))
189 return -ENOMEM;
190
191 return 0;
192 }
193
194 static int x2apic_dead_cpu(unsigned int dead_cpu)
195 {
196 struct cpumask *cmsk = per_cpu(cluster_masks, dead_cpu);
197
198 if (cmsk)
199 cpumask_clear_cpu(dead_cpu, cmsk);
200 free_cpumask_var(per_cpu(ipi_mask, dead_cpu));
201 return 0;
202 }
203
204 static int x2apic_cluster_probe(void)
205 {
206 u32 slots;
207
208 if (!x2apic_mode)
209 return 0;
210
211 slots = max_t(u32, L1_CACHE_BYTES/sizeof(u32), nr_cpu_ids);
212 x86_cpu_to_logical_apicid = kcalloc(slots, sizeof(u32), GFP_KERNEL);
213 if (!x86_cpu_to_logical_apicid)
214 return 0;
215
216 if (cpuhp_setup_state(CPUHP_X2APIC_PREPARE, "x86/x2apic:prepare",
217 x2apic_prepare_cpu, x2apic_dead_cpu) < 0) {
218 pr_err("Failed to register X2APIC_PREPARE\n");
219 kfree(x86_cpu_to_logical_apicid);
220 x86_cpu_to_logical_apicid = NULL;
221 return 0;
222 }
223 init_x2apic_ldr();
224 return 1;
225 }
226
227 static struct apic apic_x2apic_cluster __ro_after_init = {
228
229 .name = "cluster x2apic",
230 .probe = x2apic_cluster_probe,
231 .acpi_madt_oem_check = x2apic_acpi_madt_oem_check,
232
233 .dest_mode_logical = true,
234
235 .disable_esr = 0,
236
237 .init_apic_ldr = init_x2apic_ldr,
238 .cpu_present_to_apicid = default_cpu_present_to_apicid,
239
240 .max_apic_id = UINT_MAX,
241 .x2apic_set_max_apicid = true,
242 .get_apic_id = x2apic_get_apic_id,
243
244 .calc_dest_apicid = x2apic_calc_apicid,
245
246 .send_IPI = x2apic_send_IPI,
247 .send_IPI_mask = x2apic_send_IPI_mask,
248 .send_IPI_mask_allbutself = x2apic_send_IPI_mask_allbutself,
249 .send_IPI_allbutself = x2apic_send_IPI_allbutself,
250 .send_IPI_all = x2apic_send_IPI_all,
251 .send_IPI_self = x2apic_send_IPI_self,
252 .nmi_to_offline_cpu = true,
253
254 .read = native_apic_msr_read,
255 .write = native_apic_msr_write,
256 .eoi = native_apic_msr_eoi,
257 .icr_read = native_x2apic_icr_read,
258 .icr_write = native_x2apic_icr_write,
259 };
260
261 apic_driver(apic_x2apic_cluster);
262
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