1 /* SPDX-License-Identifier: GPL-2.0-or-later * 1
2 #ifndef _ASM_POWERPC_PARAVIRT_H
3 #define _ASM_POWERPC_PARAVIRT_H
4
5 #include <linux/jump_label.h>
6 #include <asm/smp.h>
7 #ifdef CONFIG_PPC64
8 #include <asm/paca.h>
9 #include <asm/lppaca.h>
10 #include <asm/hvcall.h>
11 #endif
12
13 #ifdef CONFIG_PPC_SPLPAR
14 #include <linux/smp.h>
15 #include <asm/kvm_guest.h>
16 #include <asm/cputhreads.h>
17
18 DECLARE_STATIC_KEY_FALSE(shared_processor);
19
20 static inline bool is_shared_processor(void)
21 {
22 return static_branch_unlikely(&shared_
23 }
24
25 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
26 extern struct static_key paravirt_steal_enable
27 extern struct static_key paravirt_steal_rq_ena
28
29 u64 pseries_paravirt_steal_clock(int cpu);
30
31 static inline u64 paravirt_steal_clock(int cpu
32 {
33 return pseries_paravirt_steal_clock(cp
34 }
35 #endif
36
37 /* If bit 0 is set, the cpu has been ceded, co
38 static inline u32 yield_count_of(int cpu)
39 {
40 __be32 yield_count = READ_ONCE(lppaca_
41 return be32_to_cpu(yield_count);
42 }
43
44 /*
45 * Spinlock code confers and prods, so don't t
46 * tracing code takes spinlocks which can caus
47 *
48 * These calls are made while the lock is not
49 * it can not acquire the lock, and unlock slo
50 * yielded). So this may not be a problem for
51 * tracing does not technically recurse on the
52 *
53 * However the queued spin lock contended path
54 * H_CONFER hcall is made after the task has q
55 * recursing on that lock will cause the task
56 * first instance (or worse: queued spinlocks
57 * never waits on more than one spinlock, so s
58 * corruption in the lock code).
59 */
60 static inline void yield_to_preempted(int cpu,
61 {
62 plpar_hcall_norets_notrace(H_CONFER, g
63 }
64
65 static inline void prod_cpu(int cpu)
66 {
67 plpar_hcall_norets_notrace(H_PROD, get
68 }
69
70 static inline void yield_to_any(void)
71 {
72 plpar_hcall_norets_notrace(H_CONFER, -
73 }
74
75 static inline bool is_vcpu_idle(int vcpu)
76 {
77 return lppaca_of(vcpu).idle;
78 }
79
80 static inline bool vcpu_is_dispatched(int vcpu
81 {
82 /*
83 * This is the yield_count. An "odd"
84 * the processor is yielded (either be
85 * hypervisor preempt). An even value
86 * currently executing.
87 */
88 return (!(yield_count_of(vcpu) & 1));
89 }
90 #else
91 static inline bool is_shared_processor(void)
92 {
93 return false;
94 }
95
96 static inline u32 yield_count_of(int cpu)
97 {
98 return 0;
99 }
100
101 extern void ___bad_yield_to_preempted(void);
102 static inline void yield_to_preempted(int cpu,
103 {
104 ___bad_yield_to_preempted(); /* This w
105 }
106
107 extern void ___bad_yield_to_any(void);
108 static inline void yield_to_any(void)
109 {
110 ___bad_yield_to_any(); /* This would b
111 }
112
113 extern void ___bad_prod_cpu(void);
114 static inline void prod_cpu(int cpu)
115 {
116 ___bad_prod_cpu(); /* This would be a
117 }
118
119 static inline bool is_vcpu_idle(int vcpu)
120 {
121 return false;
122 }
123 static inline bool vcpu_is_dispatched(int vcpu
124 {
125 return true;
126 }
127 #endif
128
129 #define vcpu_is_preempted vcpu_is_preempted
130 static inline bool vcpu_is_preempted(int cpu)
131 {
132 /*
133 * The dispatch/yield bit alone is an
134 * whether the hypervisor has dispatch
135 * processor. When it is clear, @cpu i
136 * But when it is set, it means only t
137 * other conditions. So we check other
138 * @cpu first, resorting to the yield
139 */
140
141 /*
142 * Hypervisor preemption isn't possibl
143 * mode by definition.
144 */
145 if (!is_shared_processor())
146 return false;
147
148 /*
149 * If the hypervisor has dispatched th
150 * processor, then the target CPU is d
151 */
152 if (vcpu_is_dispatched(cpu))
153 return false;
154
155 /*
156 * if the target CPU is not dispatched
157 * has not marked the CPU idle, then i
158 */
159 if (!is_vcpu_idle(cpu))
160 return true;
161
162 #ifdef CONFIG_PPC_SPLPAR
163 if (!is_kvm_guest()) {
164 int first_cpu, i;
165
166 /*
167 * The result of vcpu_is_preem
168 * speculative way, and is alw
169 * by events internal and exte
170 * be called in preemptable co
171 * we're not accessing per-cpu
172 * race destructively with Lin
173 * migration, and callers can
174 * error introduced by samplin
175 * pinning the task to it. So
176 * raw_smp_processor_id() here
177 * warnings that can arise fro
178 * in arbitrary contexts.
179 */
180 first_cpu = cpu_first_thread_s
181
182 /*
183 * The PowerVM hypervisor disp
184 * basis. So we know that a th
185 * cannot have been preempted
186 * has called H_CONFER, which
187 */
188 if (cpu_first_thread_sibling(c
189 return false;
190
191 /*
192 * The specific target CPU was
193 * then also check all other c
194 * because it does core schedu
195 * of the core getting preempt
196 * other vcpus can also be con
197 */
198 first_cpu = cpu_first_thread_s
199 for (i = first_cpu; i < first_
200 if (i == cpu)
201 continue;
202 if (vcpu_is_dispatched
203 return false;
204 if (!is_vcpu_idle(i))
205 return true;
206 }
207 }
208 #endif
209
210 /*
211 * None of the threads in target CPU's
212 * them were preempted too. Hence assu
213 * non-preempted.
214 */
215 return false;
216 }
217
218 static inline bool pv_is_native_spin_unlock(vo
219 {
220 return !is_shared_processor();
221 }
222
223 #endif /* _ASM_POWERPC_PARAVIRT_H */
224
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.