Commit-ID: 0bf17c102177d5da9363bf8b1e4704b9996d5079 Gitweb: https://git.kernel.org/tip/0bf17c102177d5da9363bf8b1e4704b9996d5079 Author: Tom Lendacky <thomas.lenda...@amd.com> AuthorDate: Fri, 5 Jan 2018 10:07:56 -0600 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Sat, 6 Jan 2018 21:57:40 +0100
x86/cpu/AMD: Use LFENCE_RDTSC instead of MFENCE_RDTSC With LFENCE now a serializing instruction, set the LFENCE_RDTSC feature since the LFENCE instruction has less overhead than the MFENCE instruction. Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Reviewed-by: Borislav Petkov <b...@alien8.de> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Dave Hansen <dave.han...@intel.com> Cc: Tim Chen <tim.c.c...@linux.intel.com> Cc: Greg Kroah-Hartman <gre...@linux-foundation.org> Cc: David Woodhouse <d...@amazon.co.uk> Cc: Paul Turner <p...@google.com> Cc: sta...@vger.kernel.org Link: https://lkml.kernel.org/r/20180105160756.23786.4220.st...@tlendack-t1.amdoffice.net --- arch/x86/kernel/cpu/amd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index fbd439e..b221fe5 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -838,8 +838,8 @@ static void init_amd(struct cpuinfo_x86 *c) msr_set_bit(MSR_F10H_DECFG, MSR_F10H_DECFG_LFENCE_SERIALIZE_BIT); - /* MFENCE stops RDTSC speculation */ - set_cpu_cap(c, X86_FEATURE_MFENCE_RDTSC); + /* A serializing LFENCE stops RDTSC speculation */ + set_cpu_cap(c, X86_FEATURE_LFENCE_RDTSC); } /*
