Commit-ID: 0bf17c102177d5da9363bf8b1e4704b9996d5079 Gitweb: https://git.kernel.org/tip/0bf17c102177d5da9363bf8b1e4704b9996d5079 Author: Tom Lendacky <[email protected]> AuthorDate: Fri, 5 Jan 2018 10:07:56 -0600 Committer: Thomas Gleixner <[email protected]> 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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Borislav Petkov <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Tim Chen <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: David Woodhouse <[email protected]> Cc: Paul Turner <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected] --- 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); } /*
