arch/powerpc/include/asm/paravirt.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   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/hvcall.h>
  10 #endif
  11
  12 #ifdef CONFIG_PPC_SPLPAR
  13 #include <asm/kvm_guest.h>
  14 #include <asm/cputhreads.h>
  15
  16 DECLARE_STATIC_KEY_FALSE(shared_processor);
  17
  18 static inline bool is_shared_processor(void)
  19 {
  20         return static_branch_unlikely(&shared_processor);
  21 }
  22
  23 /* If bit 0 is set, the cpu has been preempted */
  24 static inline u32 yield_count_of(int cpu)
  25 {
  26         __be32 yield_count = READ_ONCE(lppaca_of(cpu).yield_count);
  27         return be32_to_cpu(yield_count);
  28 }
  29
  30 static inline void yield_to_preempted(int cpu, u32 yield_count)
  31 {
  32         plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(cpu), yield_count);
  33 }
  34
  35 static inline void prod_cpu(int cpu)
  36 {
  37         plpar_hcall_norets(H_PROD, get_hard_smp_processor_id(cpu));
  38 }
  39
  40 static inline void yield_to_any(void)
  41 {
  42         plpar_hcall_norets(H_CONFER, -1, 0);
  43 }
  44 #else
  45 static inline bool is_shared_processor(void)
  46 {
  47         return false;
  48 }
  49
  50 static inline u32 yield_count_of(int cpu)
  51 {
  52         return 0;
  53 }
  54
  55 extern void ___bad_yield_to_preempted(void);
  56 static inline void yield_to_preempted(int cpu, u32 yield_count)
  57 {
  58         ___bad_yield_to_preempted(); /* This would be a bug */
  59 }
  60
  61 extern void ___bad_yield_to_any(void);
  62 static inline void yield_to_any(void)
  63 {
  64         ___bad_yield_to_any(); /* This would be a bug */
  65 }
  66
  67 extern void ___bad_prod_cpu(void);
  68 static inline void prod_cpu(int cpu)
  69 {
  70         ___bad_prod_cpu(); /* This would be a bug */
  71 }
  72
  73 #endif
  74
  75 #define vcpu_is_preempted vcpu_is_preempted
  76 static inline bool vcpu_is_preempted(int cpu)
  77 {
  78         if (!is_shared_processor())
  79                 return false;
  80
  81 #ifdef CONFIG_PPC_SPLPAR
  82         if (!is_kvm_guest()) {
  83                 int first_cpu = cpu_first_thread_sibling(smp_processor_id());
  84
  85                 /*
  86                  * Preemption can only happen at core granularity. This CPU
  87                  * is not preempted if one of the CPU of this core is not
  88                  * preempted.
  89                  */
  90                 if (cpu_first_thread_sibling(cpu) == first_cpu)
  91                         return false;
  92         }
  93 #endif
  94
  95         if (yield_count_of(cpu) & 1)
  96                 return true;
  97         return false;
  98 }
  99
 100 static inline bool pv_is_native_spin_unlock(void)
 101 {
 102         return !is_shared_processor();
 103 }
 104
 105 #endif /* _ASM_POWERPC_PARAVIRT_H */