On Thu, 29 Apr 2021 at 11:02, Markus Armbruster <arm...@redhat.com> wrote:
>
> If you're cc'ed, you added a section to docs/system/deprecated.rst that
> is old enough to permit removal. This is *not* a demand to remove, it's
> a polite request to consider whether the time for removal has come.
> Extra points for telling us in a reply. "We should remove, but I can't
> do it myself right now" is a valid answer. Let's review the file:
> I'm not sure there's anything to remove here, but anyway, Peter Maydell:
This isn't one of mine -- I just show up in git blame because this
section predates the conversion from texi to rst. It was originally
added by Eduardo (cc'd) in commit aa5b9692871.
> Runnability guarantee of CPU models (since 4.1.0)
> '''''''''''''''''''''''''''''''''''''''''''''''''
>
> Previous versions of QEMU never changed existing CPU models in
> ways that introduced additional host software or hardware
> requirements to the VM. This allowed management software to
> safely change the machine type of an existing VM without
> introducing new requirements ("runnability guarantee"). This
> prevented CPU models from being updated to include CPU
> vulnerability mitigations, leaving guests vulnerable in the
> default configuration.
>
> The CPU model runnability guarantee won't apply anymore to
> existing CPU models. Management software that needs runnability
> guarantees must resolve the CPU model aliases using the
> ``alias-of`` field returned by the ``query-cpu-definitions`` QMP
> command.
>
> While those guarantees are kept, the return value of
> ``query-cpu-definitions`` will have existing CPU model aliases
> point to a version that doesn't break runnability guarantees
> (specifically, version 1 of those CPU models). In future QEMU
> versions, aliases will point to newer CPU model versions
> depending on the machine type, so management software must
> resolve CPU model aliases before starting a virtual machine.
thanks
-- PMM
