On Wed, Sep 11, 2024 at 05:49:46PM +0200, Niels Dettenbach wrote:
Am Mittwoch, 11. September 2024, 10:53:30 schrieb Niels Dettenbach:
virtual machines under Xen Hypervisor (DomU) running in Xen PV mode use a special, nonstandard synthetized CPU topology which "just works" under kernels 6.9.x while newer kernels assuming a "crash kernel" and disable SMT (reducing to one CPU core) because the newer topology implementation produces a wrong error "[Firmware Bug]: APIC enumeration order not specification compliant" after new topology checks which are improper for Xen PV platform. As a result, the kernel disables SMT and activates just one CPU core within the VM (DomU).
The patch disables the regarding checks if it is running in Xen PV mode (only) and bring back SMT / all CPUs as in the past to such DomU VMs.
Signed-off-by: Niels Dettenbach nd@syndicat.com
Signed-off-by: Niels Dettenbach nd@syndicat.com
A reworked proposal patch which substitutes my initial proposed patch:
--- linux/arch/x86/kernel/cpu/topology.c 2024-09-11 17:42:42.699278317 +0200 +++ linux/arch/x86/kernel/cpu/topology.c.orig 2024-09-11 09:53:16.194095250 +0200
<snip>
Please submit this to the proper developers and maintainers for this code, as the get_maintainers script will tell you as the documentation states. As it is, this isn't going anywhere as you did not include them properly.
good luck!
greg k-h