Messages in this thread | | | Date | Tue, 26 Apr 2022 11:36:40 +0200 | From | Juergen Gross <> | Subject | Re: [PATCH V1 3/6] xen/virtio: Add option to restrict memory access under Xen |
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On 26.04.22 10:41, Borislav Petkov wrote: > On Tue, Apr 26, 2022 at 07:16:16AM +0200, Juergen Gross wrote: >> Christoph suggested (rather firmly) this would be the way to go. > > Yeah, I saw it but I don't think it is the right way to go. > > What happens the next time a guest needs to query the platform > underneath? Misuse these interfaces again? > > Because people will see the Xen use and say, hey, look, I will use this > for my funky HV too. > > Even worse: what happens if Xen decides to implement SEV/TDX? Then > you're in for a world of fun.
As the suggestion was to add another flag this wouldn't be a problem IMO.
But I agree that coco might be not the best way to go (as I wrote already).
> > Now, if we want to *extend* the interfaces to have something as generic > as, say, platform_has() and that should be the way for generic kernel > code running in the guest to query the platform capabilities, then sure, > by all means.
I agree.
> >> This is needed on guest side at a rather hypervisor independent place. >> >> So a capability of some sort seems appropriate. >> >> Another suggestion of mine was to have a callback (or flag) in >> struct x86_hyper_runtime for that purpose. > > This becomes an issue if the HV is not x86 - then you need a different > method of querying it, which then underneath will call the arch-specific > interface. > > I don't know how much of querying guests need to do and how they've been > doing that so far. Depending on the requirements, we probably should > think about a clean design from the get-go instead of homegrown things.
Yes.
platform_has() doesn't seem too bad IMO.
I will write a patch for starting the discussion.
Juergen [unhandled content-type:application/pgp-keys][unhandled content-type:application/pgp-signature] | |