Messages in this thread | | | From | "Van De Ven, Arjan" <> | Subject | RE: [PATCH v1] x86/retpoline: Use lfence in the retpoline/RSB filling RSB macros | Date | Sat, 13 Jan 2018 14:07:35 +0000 |
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> > The RSB filling macro is applicable to AMD, and, if software is unable to > > verify that lfence is serializing on AMD (possible when running under a > > hypervisor), the generic retpoline support will be used and, so, is also > > applicable to AMD. Change the use of pause to lfence. > > > > Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> > > Conditionally-Acked-by: David Woodhouse <dwmw@amazon.co.uk>
pause is technically the "save me power" instruction
how about a compromise where we do a double:
pause lfence jmp <up>
as sequence... that way if the branch recovery is fast, we get the performance of pause, but if it takes a while, on AMD you get the behavior of lfence?
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