| 1 | /* |
| 2 | * Copyright (C) 2016, Emilio G. Cota <cota@braap.org> |
| 3 | * |
| 4 | * License: GNU GPL, version 2. |
| 5 | * See the COPYING file in the top-level directory. |
| 6 | */ |
| 7 | #ifndef QEMU_PROCESSOR_H |
| 8 | #define QEMU_PROCESSOR_H |
| 9 | |
| 10 | #if defined(__x86_64__) |
| 11 | # define cpu_relax() asm volatile("rep; nop" ::: "memory") |
| 12 | |
| 13 | #elif defined(__aarch64__) |
| 14 | # define cpu_relax() asm volatile("yield" ::: "memory") |
| 15 | |
| 16 | #elif defined(__powerpc64__) |
| 17 | /* set Hardware Multi-Threading (HMT) priority to low; then back to medium */ |
| 18 | # define cpu_relax() asm volatile("or 1, 1, 1;" \ |
| 19 | "or 2, 2, 2;" ::: "memory") |
| 20 | |
| 21 | #else |
| 22 | # define cpu_relax() barrier() |
| 23 | #endif |
| 24 | |
| 25 | #endif /* QEMU_PROCESSOR_H */ |