tree 3e9b31c0f4d627f5340822a4cdad8db20dd382ca
parent 14d12bb8582e158006c35cce0f8ae1706094f9a4
author Yazen Ghannam <yazen.ghannam@amd.com> 1522764148 -0500
committer Thomas Gleixner <tglx@linutronix.de> 1524751579 +0200

x86/smpboot: Don't use mwait_play_dead() on AMD systems

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