x86/resctrl: Determine if Sub-NUMA Cluster is enabled and initialize.

There isn't a simple hardware enumeration to indicate to software that
a system is running with Sub-NUMA Cluster enabled.

Compare the number of NUMA nodes with the number of L3 caches to calculate
the number of Sub-NUMA nodes per L3 cache.

When Sub-NUMA cluster mode is enabled in BIOS setup the RMID counters
are distributed equally between the SNC nodes within each socket.

E.g. if there are 400 RMID counters, and the system is configured with
two SNC nodes per socket, then RMID counter 0..199 are used on SNC node
0 on the socket, and RMID counter 200..399 on SNC node 1.

A model specific MSR (0xca0) can change the configuration of the RMIDs
when SNC mode is enabled.

The MSR controls the interpretation of the RMID field in the
IA32_PQR_ASSOC MSR so that the appropriate hardware counters
within the SNC node are updated.

Also initialize a per-cpu RMID offset value. Use this
to calculate the value to write to the IA32_QM_EVTSEL MSR when
reading RMID event values.

N.B. this works well for well-behaved NUMA applications that access
memory predominantly from the local memory node. For applications that
access memory across multiple nodes it may be necessary for the user
to read counters for all SNC nodes on a socket and add the values to
get the actual LLC occupancy or memory bandwidth. Perhaps this isn't
all that different from applications that span across multiple sockets
in a legacy system.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Peter Newman <peternewman@google.com>
Tested-by: Peter Newman <peternewman@google.com>