[MODERATED] Re: L1D-Fault KVM mitigation

[Paolo Bonzini <pbonzini@redhat.com>]

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On 03/05/2018 18:20, speck for Konrad Rzeszutek Wilk wrote:
> On Tue, Apr 24, 2018 at 02:53:15PM +0200, speck for Paolo Bonzini wrote:
>> On 24/04/2018 11:35, speck for Peter Zijlstra wrote:
>>> I know that I worked a little with Tim on this, and I know Google did
>>> their own thing (but have not seen patches from them -- is pjt on this
>>> list?). I've also heard Amazon was also working on things (are they
>>> here?). And I think RHT was also looking into something (mingo, bonzini
>>> -- are you guys reading?)
>>
>> Yes, I am.  First of all: the cost of doing an L1D flush on every
> 
> ..snip..
> 
>> Ingo suggested, for ease of testing and also for ease of deployment, a
>> knob to easily online/offline all siblings but the first on each core.
>> There's still the chance that some userspace daemon is started before
>> hyperthreading is software-disabled that way, and is confused by the
>> number of CPUs suddenly halving, so it would have to be both on the
>> kernel command line and in debugfs.
> 
> Are there any patches that you would be willing to share so folks
> can review/test/etc? I was going to start doing this next but I suspect
> you have already most of this ?
> 

Yes, I'll send them out tomorrow.

Paolo