Le 22/01/2026 à 17:51, Alejandro Vallejo a écrit :
> While in principle it's possible to have a vendor virtualising another,
> this is fairly tricky in practice and comes with the world's supply of
> security issues.
>
> Reject any CPU policy with vendors not matching the host's.
> > Signed-off-by: Alejandro Vallejo <[email protected]>
> ---
> CHANGELOG.md | 4 ++++
> xen/lib/x86/policy.c | 3 ++-
> 2 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/CHANGELOG.md b/CHANGELOG.md
> index 18f3d10f20..eae2f961c7 100644
> --- a/CHANGELOG.md
> +++ b/CHANGELOG.md
> @@ -22,6 +22,10 @@ The format is based on [Keep a
> Changelog](https://keepachangelog.com/en/1.0.0/)
> - Xenoprofile support. Oprofile themselves removed support for Xen in
> 2014
> prior to the version 1.0 release, and there has been no development
> since
> before then in Xen.
> + - Cross-vendor support. Refuse to start domains whose CPU vendor
> differs> + from the host so that security mitigations stay consistent.
Cross-vendor
> + setups have been unreliable and not practical since 2017 with the
> advent of
> + speculation security.
>
I don't really like the wording, it sounds like guest will suddenly stop
to work for some reason. AFAIK, in the Xen Project only suspend/resume
logic is going to be affected, and we probably want to reflect on that
instead.
> - Removed xenpm tool on non-x86 platforms as it doesn't actually provide
> anything useful outside of x86.
> diff --git a/xen/lib/x86/policy.c b/xen/lib/x86/policy.c
> index f033d22785..4c0c5386ea 100644
> --- a/xen/lib/x86/policy.c
> +++ b/xen/lib/x86/policy.c
> @@ -15,7 +15,8 @@ int x86_cpu_policies_are_compatible(const struct cpu_policy
> *host,
> #define FAIL_MSR(m) \
> do { e.msr = (m); goto out; } while ( 0 )
>
> - if ( guest->basic.max_leaf > host->basic.max_leaf )
> + if ( (guest->basic.max_leaf > host->basic.max_leaf) ||
> + (guest->x86_vendor != host->x86_vendor) )
> FAIL_CPUID(0, NA);
>
> if ( guest->feat.max_subleaf > host->feat.max_subleaf )
--
Teddy Astie | Vates XCP-ng Developer
XCP-ng & Xen Orchestra - Vates solutions
web: https://vates.tech
