On Wed Feb 11, 2026 at 4:41 PM CET, Jan Beulich wrote:
> On 06.02.2026 17:15, Alejandro Vallejo wrote:
>> --- 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->x86_vendor != host->x86_vendor) ||
>
> With the subsequent "unknown" discussion also in mind, I wonder: Should we
> fail the request here when either side is "unknown"?
That'd preclude the creation of VMs on new vendors. At that point, might as
well drop support for unknown vendors altogether. I wouldn't mind that.
I was thinking of comparing the x86_vendor_id bytes instead, as I answered
to Roger. Then the invariant that only $VENDOR VMs run on $VENDOR hosts is
preserved even if we don't know about them.
Cheers,
Alejandro.
