Commit-ID: da6fa7ef67f07108a1b0cb9fd9e7fcaabd39c051 Gitweb: https://git.kernel.org/tip/da6fa7ef67f07108a1b0cb9fd9e7fcaabd39c051 Author: Yazen Ghannam <yazen.ghannam@xxxxxxx> AuthorDate: Tue, 3 Apr 2018 09:02:28 -0500 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Thu, 26 Apr 2018 16:06:19 +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@xxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Reviewed-by: Borislav Petkov <bp@xxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Cc: Yazen Ghannam <Yazen.Ghannam@xxxxxxx> Link: https://lkml.kernel.org/r/20180403140228.58540-1-Yazen.Ghannam@xxxxxxx --- 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 45175b81dd5b..0f1cbb042f49 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1571,6 +1571,8 @@ 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)) -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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