On Tue, Apr 03, 2018 at 09:02:28AM -0500, Yazen Ghannam wrote: > From: Yazen Ghannam <[email protected]> > > Recent AMD systems support using MWAIT for C1 state. However, MWAIT will > not allow deeper cstates than C1 on current systems. > > With play_dead() we expect the OS to use the deepest state available. > The deepest state available on AMD systems is reached through SystemIO > or HALT. If MWAIT is available, we use it instead of the other methods, > so we never reach the deepest state. > > Don't try to use MWAIT to play_dead() on AMD systems. Instead, we'll use > CPUIDLE to enter the deepest state advertised by firmware. If CPUIDLE is > not available then we fallback to HALT. > > Signed-off-by: Yazen Ghannam <[email protected]> > --- > Link: > https://lkml.kernel.org/r/[email protected] > > v1->v2: > * Drop comment in code. > > arch/x86/kernel/smpboot.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > index ff99e2b6fc54..12599e55e040 100644 > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -1536,6 +1536,8 @@ static inline void mwait_play_dead(void) > void *mwait_ptr; > int i; > > + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) > + return; > if (!this_cpu_has(X86_FEATURE_MWAIT)) > return; > if (!this_cpu_has(X86_FEATURE_CLFLUSH)) > --
Reviewed-by: Borislav Petkov <[email protected]> -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --
