diff options
Diffstat (limited to 'include/asm-i386/tsc.h')
| -rw-r--r-- | include/asm-i386/tsc.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/asm-i386/tsc.h b/include/asm-i386/tsc.h index 0181f9df753..3f3c1fa000b 100644 --- a/include/asm-i386/tsc.h +++ b/include/asm-i386/tsc.h @@ -38,6 +38,15 @@ static __always_inline cycles_t get_cycles_sync(void) unsigned eax; /* + * Use RDTSCP if possible; it is guaranteed to be synchronous + * and doesn't cause a VMEXIT on Hypervisors + */ + alternative_io(ASM_NOP3, ".byte 0x0f,0x01,0xf9", X86_FEATURE_RDTSCP, + "=A" (ret), "0" (0ULL) : "ecx", "memory"); + if (ret) + return ret; + + /* * Don't do an additional sync on CPUs where we know * RDTSC is already synchronous: */ |