powerpc/powernv: copy/paste - Mask XERS0 bit in CR

[Haren Myneni]

NX can set 3rd bit in CR register for XER[SO] (Summation overflow)
which is not related to paste request. The current paste function
returns failure for the successful request when this bit is set.
So mask this bit and check the proper return status.

Fixes: 2392c8c8c045 ("powerpc/powernv/vas: Define copy/paste interfaces")
Cc: stable at vger.kernel.org # v4.14+    
Signed-off-by: Haren Myneni <haren at us.ibm.com>

diff --git a/arch/powerpc/platforms/powernv/copy-paste.h b/arch/powerpc/platforms/powernv/copy-paste.h
index c9a5036..82392e3 100644
--- a/arch/powerpc/platforms/powernv/copy-paste.h
+++ b/arch/powerpc/platforms/powernv/copy-paste.h
@@ -9,7 +9,8 @@
 #include <asm/ppc-opcode.h>
 
 #define CR0_SHIFT	28
-#define CR0_MASK	0xF
+#define CR0_MASK	0xE /* 3rd bit undefined or set for XER[SO] */
+
 /*
  * Copy/paste instructions:
  *