Pseudo-locking can work when Code and Data Prioritization (CDP) is enabled,
but there are a few additional checks and actions involved. At this time
it is not clear if users would want to use pseudo-locking and CDP at the
same time so the support of this is delayed until we understand the
usage better.

Disable pseudo-locking if CDP is enabled. Add the details of things to
keep in mind for anybody considering enabling this support.

Signed-off-by: Reinette Chatre <>
 arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c | 30 +++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c 
index a0c144b5b09b..f6932a7de6e7 100644
--- a/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
+++ b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
@@ -443,6 +443,36 @@ int rdt_pseudo_lock_fs_init(struct kernfs_node *root)
+        * Pseudo-locking not supported when CDP is enabled.
+        *
+        * Some things to consider if you would like to enable this support
+        * (using L3 CDP as example):
+        * - When CDP is enabled two separate resources are exposed, L3DATA
+        *   and L3CODE, but they are actually on the same cache. The
+        *   implication for pseudo-locking is that if a pseudo-locked
+        *   region is created on a domain of one resource (eg. L3CODE),
+        *   then a pseudo-locked region cannot be created on that same
+        *   domain of the other resource (eg. L3DATA). This is because
+        *   the creation of a pseudo-locked region involves a call to
+        *   wbinvd that will affect all cache allocations on particular
+        *   domain.
+        * - Considering the previous, it may be possible to only expose
+        *   one of the CDP resources to pseudo-locking and hide the other.
+        *   For example, we could consider to only expose L3DATA and since
+        *   the L3 cache is unified it is still possible to place
+        *   instructions there are execute it.
+        * - If only one region is exposed to pseudo-locking we should still
+        *   keep in mind that availability of a portion of cache for
+        *   pseudo-locking should take into account both resources. Similarly,
+        *   if a pseudo-locked region is created in one resource, the portion
+        *   of cache used by it should be made unavailable to all future
+        *   allocations from both resources.
+        */
+       if (rdt_resources_all[RDT_RESOURCE_L3DATA].alloc_enabled ||
+           rdt_resources_all[RDT_RESOURCE_L2DATA].alloc_enabled)
+               return 0;
+       /*
         * Not knowing the bits to disable prefetching is not a failure
         * that should be propagated since we only return prefetching bits
         * for those platforms pseudo-locking has been tested on. If

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