xen resource reporting

[Alex Smirnoff]

It is rather a xen issue, but I did not find xen groups alive enough, so..

I have a 6-core cpu, so.. xen thinks there are two "CPU's" per core, probably due to HT.
And it does, apparently, cause a lot of confusion.

from "xenpm start 1:

Socket 0
     Core 0 CPU 0
     Core 1 CPU 2
     Core 2 CPU 4
     Core 3 CPU 6
     Core 4 CPU 8
     Core 5 CPU 10

But, when I try to get CPU states, xenpm assumes the core count to the cpu count! thus, it tries to get status of CPU0-CPU5, which succeeds only for even CPUs, odd CPUs get dropped and return error when xenp tries to control them, and CPU6-CPU10 are ingored.

also, xenpm get-cpufreq-para returns obviously incorrect values (for even CPUs only, again, for odd ones it just "falied to get cpufreq parameter" and 6-10 are igored), as well as xentop. At the same time, values at get-cpufreq-average are apparently right.

Is it a known issue?

[superiorimmunity]

Yes, similar things mentioned here https://github.com/QubesOS/qubes-issues/issues/4252 and here https://github.com/QubesOS/qubes-issues/issues/4456

Additional logical cores have been disabled in Qubes OS to mitigate serious vulnerability https://www.qubes-os.org/news/2018/09/02/qsb-43/ , in this QSB it is also shown how to re-enable Hyper-Threading (SMT), though it's not recommended.

To make xenpm show only physical cores disable Hyper-Threading in UEFI (suggested in issue 4252).

But to make it show correct frequencies it may be needed 1) disable GT in UEFI 2) re-enable SMT in xen.cfg (it shouldn't have adverse effects since HT already disabled in UEFI)