powerpc/64s: Remove ICSWX feature from Power9

Power9 does not implement the icswx instruction. This CPU feature is not visible
to userspace and is only used in the CONFIG_PPC_ICSWX code, which is generally
not enabled, and can only be triggered by other code using icswx, which should
not happen on Power9 systems in the first place. So impact should be minimal.

Fixes: c3ab300 ("powerpc: Add POWER9 cputable entry")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/cputable.h

@@ -471,7 +471,7 @@ enum {
 	    CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
 	    CPU_FTR_DSCR | CPU_FTR_SAO  | \
 	    CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \
-	    CPU_FTR_ICSWX | CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
+	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
 	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_DAWR | \
 	    CPU_FTR_ARCH_207S | CPU_FTR_TM_COMP | CPU_FTR_ARCH_300)
 #define CPU_FTRS_POWER9_DD1 (CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1)

arch/powerpc/platforms/Kconfig.cputype

@@ -279,7 +279,8 @@ config PPC_ICSWX
 
 	  This option enables kernel support for the PowerPC Initiate
 	  Coprocessor Store Word (icswx) coprocessor instruction on POWER7
-	  or newer processors.
+	  and POWER8 processors. POWER9 uses new copy/paste instructions
+	  to invoke the coprocessor.
 
 	  This option is only useful if you have a processor that supports
 	  the icswx coprocessor instruction. It does not have any effect