[tip:x86/urgent] x86/pkeys: Update documentation about availability

[tip-bot for Dave Hansen <tipbot@zytor.com>]

Commit-ID:  c51ff2c7fc45da8b18b28c4f15eca5a9975dfb59
Gitweb:     https://git.kernel.org/tip/c51ff2c7fc45da8b18b28c4f15eca5a9975dfb59
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Fri, 10 Nov 2017 16:12:28 -0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 21 Nov 2017 09:34:52 +0100

x86/pkeys: Update documentation about availability

Now that CPUs that implement Memory Protection Keys are publicly
available we can be a bit less oblique about where it is available.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20171111001228.DC748A10@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 Documentation/x86/protection-keys.txt | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/Documentation/x86/protection-keys.txt b/Documentation/x86/protection-keys.txt
index fa46dcb..ecb0d2d 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