Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH v6 5/6] Optionally flush L1D on context switch | Date | Thu, 14 May 2020 13:33:02 +0200 |
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Balbir,
"Singh, Balbir" <sblbir@amazon.com> writes: > On Wed, 2020-05-13 at 18:16 +0200, Thomas Gleixner wrote: >> Balbir Singh <sblbir@amazon.com> writes: >> But looking at this deeper (yes I should have noticed earlier): >> >> Why do we need yet another PRCTL? >> >> We already have PR_SET_SPECULATION_CTRL/PR_GET_SPECULATION_CTRL. That >> L1D flush thingy fits into this category, right? > > It does, I thought about it for a while when I was changing the code and > left it aside because, looking at the definition > > 1 PR_SPEC_ENABLE The speculation feature is enabled, > mitigation is disabled. > 2 PR_SPEC_DISABLE The speculation feature is disabled, > mitigation is enabled. > > With L1D flush, there is no overriding of the feature as such (as in > enable when the mitigation is disabled and vice-versa). I am happy to > reconsider my initial thought though.
L1D is always enabled as L1D will be a source of trouble forever :)
Thanks,
tglx
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