On Tue, 14 Oct 2025 at 14:22, Daniel P. Berrangé <[email protected]> wrote:
>
> On Tue, Oct 14, 2025 at 01:20:07PM +0100, Peter Maydell wrote:
> > On Mon, 13 Oct 2025 at 12:47, Daniel P. Berrangé <[email protected]> 
> > wrote:
> > > With a very minimal wording tweak our current defined policy could
> > > avoid being a blocker for enabling KVM in imx8mp-evk. In
> > >
> > >   https://www.qemu.org/docs/master/system/security.html
> > >
> > > where it describes the "virtualization use case", we could simply
> > > tweak it to always require a versioned machine type
> > >
> > > Change
> > >
> > >   "These use cases rely on hardware virtualization extensions
> > >    to execute guest code safely on the physical CPU at close-
> > >    to-native speed."
> > >
> > > To say
> > >
> > >   "These use cases apply to versioned machine types when used
> > >    in combination with hardware virtualization extensions
> > >    to execute guest code safely on the physical CPU at close-
> > >    to-native speed"
> >
> > With the suggested changes listed elsewhere in this
> > thread, my current manually curated list of machines is:
> >
> > aarch64
> >   ``virt``
> > i386, x86_64
> >   ``microvm``, ``xenfv``, ``xenpv``, ``xenpvh``, ``pc``, ``q35``
> > s390x
> >   ``s390-ccw-virtio``
> > loongarch64:
> >   ``virt``
> > ppc64:
> >   ``pseries``
> > riscv32, riscv64:
> >   ``virt``
> >
> > If we say "versioned machine type", that puts these machines
> > outside the "supported" boundary:
> >
> > i386, x86_64
> >   ``microvm``, ``xenfv``, ``xenpv``, ``xenpvh``
> > loongarch64:
> >   ``virt``
> > riscv32, riscv64:
> >   ``virt``
> >
> > I can certainly see the argument for loongarch64
> > and maybe even riscv[*] still being "not supported for
> > production security-boundary stuff", but do we really
> > want to say that the Xen machine types and microvm
> > aren't suitable for VM use ?
>
> No, that would be wrong. How about this alternative
>
>   @@ -21,7 +21,9 @@ Virtualization Use Case
>    The virtualization use case covers cloud and virtual private server (VPS)
>    hosting, as well as traditional data center and desktop virtualization.  
> These
>    use cases rely on hardware virtualization extensions to execute guest code
>   -safely on the physical CPU at close-to-native speed.
>   +safely on the physical CPU at close-to-native speed.  This use case is 
> limited
>   +to the use of versioned machine types, or machine types designed 
> exclusively
>   +for virtualization.
>
>  The following entities are untrusted, meaning that they may be buggy or
>  malicious:
>
> that wording would bring xen* and microvm into the scope, and so match
> your manually curated list.

I think that it's simpler for users if we explicitly list the
machines, rather than making them guess whether a machine
is "designed exclusively for virtualization".

thanks
-- PMM

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