diff options
Diffstat (limited to 'tools/testing/selftests/kvm/include/x86_64/processor.h')
| -rw-r--r-- | tools/testing/selftests/kvm/include/x86_64/processor.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h index c0c7c1fe93f9..a0c1440017bb 100644 --- a/tools/testing/selftests/kvm/include/x86_64/processor.h +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h @@ -23,6 +23,7 @@ extern bool host_cpu_is_intel; extern bool host_cpu_is_amd; +extern uint64_t guest_tsc_khz; /* Forced emulation prefix, used to invoke the emulator unconditionally. */ #define KVM_FEP "ud2; .byte 'k', 'v', 'm';" @@ -816,6 +817,23 @@ static inline void cpu_relax(void) asm volatile("rep; nop" ::: "memory"); } +static inline void udelay(unsigned long usec) +{ + uint64_t start, now, cycles; + + GUEST_ASSERT(guest_tsc_khz); + cycles = guest_tsc_khz / 1000 * usec; + + /* + * Deliberately don't PAUSE, a.k.a. cpu_relax(), so that the delay is + * as accurate as possible, e.g. doesn't trigger PAUSE-Loop VM-Exits. + */ + start = rdtsc(); + do { + now = rdtsc(); + } while (now - start < cycles); +} + #define ud2() \ __asm__ __volatile__( \ "ud2\n" \ |