-
Yazen Ghannam authored
Recent AMD systems support using MWAIT for C1 state. However, MWAIT will not allow deeper cstates than C1 on current systems. play_dead() expects to use the deepest state available. The deepest state available on AMD systems is reached through SystemIO or HALT. If MWAIT is available, it is preferred over the other methods, so the CPU never reaches the deepest possible state. Don't try to use MWAIT to play_dead() on AMD systems. Instead, use CPUIDLE to enter the deepest state advertised by firmware. If CPUIDLE is not available then fallback to HALT. Signed-off-by:
Yazen Ghannam <yazen.ghannam@amd.com> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Reviewed-by:
Borislav Petkov <bp@suse.de> Cc: stable@vger.kernel.org Cc: Yazen Ghannam <Yazen.Ghannam@amd.com> Link: https://lkml.kernel.org/r/20180403140228.58540-1-Yazen.Ghannam@amd.com
da6fa7ef