Re: [PATCH 0/3] arch/x86: Optionally flush L1D on context switch

[Singh, Balbir]

On Thu, 2020-04-02 at 15:13 -0500, Josh Poimboeuf wrote:
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> On Thu, Apr 02, 2020 at 05:23:58PM +1100, Balbir Singh wrote:
> > Provide a mechanisn to flush the L1D cache on context switch.  The goal
> > is to allow tasks that are paranoid due to the recent snoop assisted data
> > sampling vulnerabilites, to flush their L1D on being switched out.
> 
> Hi Balbir,
> 
> Just curious, is it really vulnerabilities, plural?  I thought there was
> only one: CVE-2020-0550 (Snoop-assisted L1 Data Sampling).
> 
> (There was a similar one without the "snoop": L1D Eviction Sampling, but
> it's supposed to get fixed in microcode).
> 

Hi, Josh

Yes, that CVE the motivation, the mitigation for CVE-2020-0550 does suggest
flushing the cache on context switch. But in general, as we begin to find more
ways of evicting data or snopping data, a generic mechanism is more useful and
that is why I am making it an opt-in.

Balbir Singh.