The Intel Software Developer's Manual defines the scope of HFI (registers
and memory buffer) as a package. Use package scope(*) in the software
representation of an HFI instance.
Using die scope in HFI instances has the effect of creating multiple
conflicting instances for the same package: each instance allocates its
own memory buffer and configures the same package-level registers.
Specifically, only one of the allocated memory buffers can be set in the
MSR_IA32_HW_FEEDBACK_PTR register. CPUs get incorrect HFI data from the
table.
The problem does not affect current HFI-capable platforms because they
all have single-die processors.
(*) We used die scope for HFI instances because there had been
processors with packages enumerated as dies. None of those systems
supported HFI, though. If such a system emerged, it would need to
be quirked.
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Link: https://patch.msgid.link/20240703055445.125362-1-rui.zhang@intel.com
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
b755367602