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authorYazen Ghannam <yazen.ghannam@amd.com>2018-04-03 09:02:28 -0500
committerThomas Gleixner <tglx@linutronix.de>2018-04-26 16:06:19 +0200
commitda6fa7ef67f07108a1b0cb9fd9e7fcaabd39c051 (patch)
tree3e9b31c0f4d627f5340822a4cdad8db20dd382ca
parent14d12bb8582e158006c35cce0f8ae1706094f9a4 (diff)
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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
-rw-r--r--arch/x86/kernel/smpboot.c2
1 files changed, 2 insertions, 0 deletions
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))