RE: [patch v2 21/38] x86/cpu: Provide cpu_init/parse_topology()

[Thomas Gleixner]

On Mon, Jul 31 2023 at 16:10, Michael Kelley wrote:
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Sent: Monday, July 31, 2023 8:38 AM
> The VM is an F72s_v2 in Azure running your patch set.  The VM has
> 72 vCPUs in two NUMA nodes across two physical Intel processors, with
> 36 vCPUs in each NUMA node.
>
> The output is from /sys/kernel/debug/x86/topo/cpus, so the initial_apicid
> is from CPUID, while the apicid is from read_apic_id() and matches the
> MADT.  As expected, the two values match for the first 36 vCPUs, but differ
> by 28 (decimal) for the remaining 36.
>
> initial_apicid:      0 apicid:              0
...
> initial_apicid:      23 apicid:              23

> initial_apicid:      40 apicid:              24
...
> initial_apicid:      63 apicid:              47

Is there any indication in some other CPUID leaf which lets us deduce this
wreckage?

I don't think the hypervisor space (0x40000xx) has anything helpful, but
staring at the architectural ones provided by hyper-V to the guest might
give us an hint. Can you provide a cpuid dump for the boot CPU please?

Thanks,

        tglx