1 // SPDX-License-Identifier: GPL-2.0
2
3 /*
4 * Hyper-V specific APIC code.
5 *
6 * Copyright (C) 2018, Microsoft, Inc.
7 *
8 * Author : K. Y. Srinivasan <kys@microsoft.com>
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License version 2 as published
12 * by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
17 * NON INFRINGEMENT. See the GNU General Public License for more
18 * details.
19 *
20 */
21
22 #include <linux/types.h>
23 #include <linux/vmalloc.h>
24 #include <linux/mm.h>
25 #include <linux/clockchips.h>
26 #include <linux/hyperv.h>
27 #include <linux/slab.h>
28 #include <linux/cpuhotplug.h>
29 #include <asm/hypervisor.h>
30 #include <asm/mshyperv.h>
31 #include <asm/apic.h>
32
33 #include <asm/trace/hyperv.h>
34
35 static struct apic orig_apic;
36
37 static u64 hv_apic_icr_read(void)
38 {
39 u64 reg_val;
40
41 rdmsrl(HV_X64_MSR_ICR, reg_val);
42 return reg_val;
43 }
44
45 static void hv_apic_icr_write(u32 low, u32 id)
46 {
47 u64 reg_val;
48
49 reg_val = SET_XAPIC_DEST_FIELD(id);
50 reg_val = reg_val << 32;
51 reg_val |= low;
52
53 wrmsrl(HV_X64_MSR_ICR, reg_val);
54 }
55
56 static u32 hv_apic_read(u32 reg)
57 {
58 u32 reg_val, hi;
59
60 switch (reg) {
61 case APIC_EOI:
62 rdmsr(HV_X64_MSR_EOI, reg_val, hi);
63 (void)hi;
64 return reg_val;
65 case APIC_TASKPRI:
66 rdmsr(HV_X64_MSR_TPR, reg_val, hi);
67 (void)hi;
68 return reg_val;
69
70 default:
71 return native_apic_mem_read(reg);
72 }
73 }
74
75 static void hv_apic_write(u32 reg, u32 val)
76 {
77 switch (reg) {
78 case APIC_EOI:
79 wrmsr(HV_X64_MSR_EOI, val, 0);
80 break;
81 case APIC_TASKPRI:
82 wrmsr(HV_X64_MSR_TPR, val, 0);
83 break;
84 default:
85 native_apic_mem_write(reg, val);
86 }
87 }
88
89 static void hv_apic_eoi_write(void)
90 {
91 struct hv_vp_assist_page *hvp = hv_vp_assist_page[smp_processor_id()];
92
93 if (hvp && (xchg(&hvp->apic_assist, 0) & 0x1))
94 return;
95
96 wrmsr(HV_X64_MSR_EOI, APIC_EOI_ACK, 0);
97 }
98
99 static bool cpu_is_self(int cpu)
100 {
101 return cpu == smp_processor_id();
102 }
103
104 /*
105 * IPI implementation on Hyper-V.
106 */
107 static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector,
108 bool exclude_self)
109 {
110 struct hv_send_ipi_ex *ipi_arg;
111 unsigned long flags;
112 int nr_bank = 0;
113 u64 status = HV_STATUS_INVALID_PARAMETER;
114
115 if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
116 return false;
117
118 local_irq_save(flags);
119 ipi_arg = *this_cpu_ptr(hyperv_pcpu_input_arg);
120
121 if (unlikely(!ipi_arg))
122 goto ipi_mask_ex_done;
123
124 ipi_arg->vector = vector;
125 ipi_arg->reserved = 0;
126 ipi_arg->vp_set.valid_bank_mask = 0;
127
128 /*
129 * Use HV_GENERIC_SET_ALL and avoid converting cpumask to VP_SET
130 * when the IPI is sent to all currently present CPUs.
131 */
132 if (!cpumask_equal(mask, cpu_present_mask) || exclude_self) {
133 ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K;
134
135 nr_bank = cpumask_to_vpset_skip(&ipi_arg->vp_set, mask,
136 exclude_self ? cpu_is_self : NULL);
137
138 /*
139 * 'nr_bank <= 0' means some CPUs in cpumask can't be
140 * represented in VP_SET. Return an error and fall back to
141 * native (architectural) method of sending IPIs.
142 */
143 if (nr_bank <= 0)
144 goto ipi_mask_ex_done;
145 } else {
146 ipi_arg->vp_set.format = HV_GENERIC_SET_ALL;
147 }
148
149 status = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank,
150 ipi_arg, NULL);
151
152 ipi_mask_ex_done:
153 local_irq_restore(flags);
154 return hv_result_success(status);
155 }
156
157 static bool __send_ipi_mask(const struct cpumask *mask, int vector,
158 bool exclude_self)
159 {
160 int cur_cpu, vcpu, this_cpu = smp_processor_id();
161 struct hv_send_ipi ipi_arg;
162 u64 status;
163 unsigned int weight;
164
165 trace_hyperv_send_ipi_mask(mask, vector);
166
167 weight = cpumask_weight(mask);
168
169 /*
170 * Do nothing if
171 * 1. the mask is empty
172 * 2. the mask only contains self when exclude_self is true
173 */
174 if (weight == 0 ||
175 (exclude_self && weight == 1 && cpumask_test_cpu(this_cpu, mask)))
176 return true;
177
178 /* A fully enlightened TDX VM uses GHCI rather than hv_hypercall_pg. */
179 if (!hv_hypercall_pg) {
180 if (ms_hyperv.paravisor_present || !hv_isolation_type_tdx())
181 return false;
182 }
183
184 if (vector < HV_IPI_LOW_VECTOR || vector > HV_IPI_HIGH_VECTOR)
185 return false;
186
187 /*
188 * From the supplied CPU set we need to figure out if we can get away
189 * with cheaper HVCALL_SEND_IPI hypercall. This is possible when the
190 * highest VP number in the set is < 64. As VP numbers are usually in
191 * ascending order and match Linux CPU ids, here is an optimization:
192 * we check the VP number for the highest bit in the supplied set first
193 * so we can quickly find out if using HVCALL_SEND_IPI_EX hypercall is
194 * a must. We will also check all VP numbers when walking the supplied
195 * CPU set to remain correct in all cases.
196 */
197 if (hv_cpu_number_to_vp_number(cpumask_last(mask)) >= 64)
198 goto do_ex_hypercall;
199
200 ipi_arg.vector = vector;
201 ipi_arg.cpu_mask = 0;
202
203 for_each_cpu(cur_cpu, mask) {
204 if (exclude_self && cur_cpu == this_cpu)
205 continue;
206 vcpu = hv_cpu_number_to_vp_number(cur_cpu);
207 if (vcpu == VP_INVAL)
208 return false;
209
210 /*
211 * This particular version of the IPI hypercall can
212 * only target up to 64 CPUs.
213 */
214 if (vcpu >= 64)
215 goto do_ex_hypercall;
216
217 __set_bit(vcpu, (unsigned long *)&ipi_arg.cpu_mask);
218 }
219
220 status = hv_do_fast_hypercall16(HVCALL_SEND_IPI, ipi_arg.vector,
221 ipi_arg.cpu_mask);
222 return hv_result_success(status);
223
224 do_ex_hypercall:
225 return __send_ipi_mask_ex(mask, vector, exclude_self);
226 }
227
228 static bool __send_ipi_one(int cpu, int vector)
229 {
230 int vp = hv_cpu_number_to_vp_number(cpu);
231 u64 status;
232
233 trace_hyperv_send_ipi_one(cpu, vector);
234
235 if (vp == VP_INVAL)
236 return false;
237
238 /* A fully enlightened TDX VM uses GHCI rather than hv_hypercall_pg. */
239 if (!hv_hypercall_pg) {
240 if (ms_hyperv.paravisor_present || !hv_isolation_type_tdx())
241 return false;
242 }
243
244 if (vector < HV_IPI_LOW_VECTOR || vector > HV_IPI_HIGH_VECTOR)
245 return false;
246
247 if (vp >= 64)
248 return __send_ipi_mask_ex(cpumask_of(cpu), vector, false);
249
250 status = hv_do_fast_hypercall16(HVCALL_SEND_IPI, vector, BIT_ULL(vp));
251 return hv_result_success(status);
252 }
253
254 static void hv_send_ipi(int cpu, int vector)
255 {
256 if (!__send_ipi_one(cpu, vector))
257 orig_apic.send_IPI(cpu, vector);
258 }
259
260 static void hv_send_ipi_mask(const struct cpumask *mask, int vector)
261 {
262 if (!__send_ipi_mask(mask, vector, false))
263 orig_apic.send_IPI_mask(mask, vector);
264 }
265
266 static void hv_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
267 {
268 if (!__send_ipi_mask(mask, vector, true))
269 orig_apic.send_IPI_mask_allbutself(mask, vector);
270 }
271
272 static void hv_send_ipi_allbutself(int vector)
273 {
274 hv_send_ipi_mask_allbutself(cpu_online_mask, vector);
275 }
276
277 static void hv_send_ipi_all(int vector)
278 {
279 if (!__send_ipi_mask(cpu_online_mask, vector, false))
280 orig_apic.send_IPI_all(vector);
281 }
282
283 static void hv_send_ipi_self(int vector)
284 {
285 if (!__send_ipi_one(smp_processor_id(), vector))
286 orig_apic.send_IPI_self(vector);
287 }
288
289 void __init hv_apic_init(void)
290 {
291 if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
292 pr_info("Hyper-V: Using IPI hypercalls\n");
293 /*
294 * Set the IPI entry points.
295 */
296 orig_apic = *apic;
297
298 apic_update_callback(send_IPI, hv_send_ipi);
299 apic_update_callback(send_IPI_mask, hv_send_ipi_mask);
300 apic_update_callback(send_IPI_mask_allbutself, hv_send_ipi_mask_allbutself);
301 apic_update_callback(send_IPI_allbutself, hv_send_ipi_allbutself);
302 apic_update_callback(send_IPI_all, hv_send_ipi_all);
303 apic_update_callback(send_IPI_self, hv_send_ipi_self);
304 }
305
306 if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
307 pr_info("Hyper-V: Using enlightened APIC (%s mode)",
308 x2apic_enabled() ? "x2apic" : "xapic");
309 /*
310 * When in x2apic mode, don't use the Hyper-V specific APIC
311 * accessors since the field layout in the ICR register is
312 * different in x2apic mode. Furthermore, the architectural
313 * x2apic MSRs function just as well as the Hyper-V
314 * synthetic APIC MSRs, so there's no benefit in having
315 * separate Hyper-V accessors for x2apic mode. The only
316 * exception is hv_apic_eoi_write, because it benefits from
317 * lazy EOI when available, but the same accessor works for
318 * both xapic and x2apic because the field layout is the same.
319 */
320 apic_update_callback(eoi, hv_apic_eoi_write);
321 if (!x2apic_enabled()) {
322 apic_update_callback(read, hv_apic_read);
323 apic_update_callback(write, hv_apic_write);
324 apic_update_callback(icr_write, hv_apic_icr_write);
325 apic_update_callback(icr_read, hv_apic_icr_read);
326 }
327 }
328 }
329
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