x86/resctrl: Fix SNC detection

Now that the x86 topology code has a sensible nodes-per-package
measure, that does not depend on the online status of CPUs, use this
to divinate the SNC mode.

Note that when Cluster on Die (CoD) is configured on older systems this
will also show multiple NUMA nodes per package. Intel Resource Director
Technology is incomaptible with CoD. Print a warning and do not use the
fixup MSR_RMID_SNC_CONFIG.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Chen Yu <yu.c.chen@intel.com>
Link: https://patch.msgid.link/aaCxbbgjL6OZ6VMd@agluck-desk3
Link: https://patch.msgid.link/20260303110100.367976706@infradead.org
This commit is contained in:
Tony Luck 2026-03-03 11:55:44 +01:00 • committed by Peter Zijlstra
commit 59674fc9d0