On Sat, 6 Jan 2018, tip-bot for Tom Lendacky wrote: > Commit-ID: 0bf17c102177d5da9363bf8b1e4704b9996d5079 > Gitweb: https://git.kernel.org/tip/0bf17c102177d5da9363bf8b1e4704b9996d5079 > Author: Tom Lendacky <thomas.lendacky@xxxxxxx> > AuthorDate: Fri, 5 Jan 2018 10:07:56 -0600 > Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > 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. Second thoughts on that. As pointed out by someone in one of the insane long threads: What happens if the kernel runs as a guest and - the hypervisor did not set the LFENCE to serializing on the host - the hypervisor does not allow writing MSR_AMD64_DE_CFG That would bring the guest into a pretty bad state or am I missing something essential here? I'm dropping these patches until this question is answered. Thanks, tglx -- 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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