powerpc/xmon: don't access ASDR in VMs

ASDR is HV-privileged and must only be accessed in HV-mode.
Fixes a Program Check (0x700) when xmon in a VM dumps SPRs.

Fixes: d1e1b351 ("powerpc/xmon: Add ISA v3.0 SPRs to SPR dump")
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200107021633.GB29843@us.ibm.com

arch/powerpc/xmon/xmon.c

@@ -1949,15 +1949,14 @@ static void dump_300_sprs(void)
 
 	printf("pidr   = %.16lx  tidr  = %.16lx\n",
 		mfspr(SPRN_PID), mfspr(SPRN_TIDR));
-	printf("asdr   = %.16lx  psscr = %.16lx\n",
-		mfspr(SPRN_ASDR), hv ? mfspr(SPRN_PSSCR)
-					: mfspr(SPRN_PSSCR_PR));
+	printf("psscr  = %.16lx\n",
+		hv ? mfspr(SPRN_PSSCR) : mfspr(SPRN_PSSCR_PR));
 
 	if (!hv)
 		return;
 
-	printf("ptcr   = %.16lx\n",
-		mfspr(SPRN_PTCR));
+	printf("ptcr   = %.16lx  asdr  = %.16lx\n",
+		mfspr(SPRN_PTCR), mfspr(SPRN_ASDR));
 #endif
 }