Messages in this thread | | | Subject | Re: [RFC v2-fix-v2 2/2] x86/tdx: Ignore WBINVD instruction for TDX guest | From | Andi Kleen <> | Date | Mon, 24 May 2021 17:39:47 -0700 |
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On 5/24/2021 4:42 PM, Dave Hansen wrote: > On 5/24/21 4:32 PM, Kuppuswamy Sathyanarayanan wrote: >> Functionally only DMA devices can notice a side effect from >> WBINVD's cache flushing. > This seems to be trying to make some kind of case that the only visible > effects from WBINVD are for DMA devices. That's flat out wrong. It > might be arguable that none of the other cases exist in a TDX guest, but > it doesn't excuse making such a broad statement without qualification.
We're describing a few sentences down that guests run with EPT IgnorePAT=1, which is the qualification.
> > Just grep in the kernel for a bunch of reasons this is wrong. > > Where did this come from?
Again the logic is very simple: TDX guest code is (mostly) about replacing KVM code with in kernel code, so we're just doing the same as KVM. You cannot get any more proven than that.
-Andi
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