diff --git a/Documentation/x86/protection-keys.txt b/Documentation/x86/protection-keys.txt
index fa46dcb347bc1d2ac60901c4621bd3bad81de601..ecb0d2dadfb769a83b2a3a3f4a20ce03df0aea79 100644
--- a/Documentation/x86/protection-keys.txt
+++ b/Documentation/x86/protection-keys.txt
@@ -1,5 +1,10 @@
-Memory Protection Keys for Userspace (PKU aka PKEYs) is a CPU feature
-which will be found on future Intel CPUs.
+Memory Protection Keys for Userspace (PKU aka PKEYs) is a feature
+which is found on Intel's Skylake "Scalable Processor" Server CPUs.
+It will be avalable in future non-server parts.
+
+For anyone wishing to test or use this feature, it is available in
+Amazon's EC2 C5 instances and is known to work there using an Ubuntu
+17.04 image.
 
 Memory Protection Keys provides a mechanism for enforcing page-based
 protections, but without requiring modification of the page tables