tree 8a55ed74b927bbf64cabba9512b8e2d4c9c14660
parent 521348b011d64cf3febb10b64ba5b472681bef94
author Reinette Chatre <reinette.chatre@intel.com> 1538605022 -0700
committer Ingo Molnar <mingo@kernel.org> 1539067843 +0200

x86/intel_rdt: CBM overlap should also check for overlap with CDP peer

The CBM overlap test is used to manage the allocations of RDT resources
where overlap is possible between resource groups. When a resource group
is in exclusive mode then there should be no overlap between resource
groups.

The current overlap test only considers overlap between the same
resources, for example, that usage of a RDT_RESOURCE_L2DATA resource
in one resource group does not overlap with usage of a RDT_RESOURCE_L2DATA
resource in another resource group. The problem with this is that it
allows overlap between a RDT_RESOURCE_L2DATA resource in one resource
group with a RDT_RESOURCE_L2CODE resource in another resource group -
even if both resource groups are in exclusive mode. This is a problem
because even though these appear to be different resources they end up
sharing the same underlying hardware and thus does not fulfill the
user's request for exclusive use of hardware resources.

Fix this by including the CDP peer (if there is one) in every CBM
overlap test. This does not impact the overlap between resources
within the same exclusive resource group that is allowed.

Fixes: 49f7b4efa110 ("x86/intel_rdt: Enable setting of exclusive mode")
Reported-by: Jithu Joseph <jithu.joseph@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jithu Joseph <jithu.joseph@intel.com>
Acked-by: Fenghua Yu <fenghua.yu@intel.com>
Cc: tony.luck@intel.com
Cc: gavin.hindman@intel.com
Cc: dave.hansen@intel.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/e538b7f56f7ca15963dce2e00ac3be8edb8a68e1.1538603665.git.reinette.chatre@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>