target/ppc: Implement PNOP

The illegal suffix behavior matches what was observed in a
POWER10 DD2.0 machine.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Message-Id: <20210601193528.2533031-6-matheus.ferst@eldorado.org.br>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

target/ppc/insn64.decode

@@ -28,3 +28,70 @@
 
 PADDI           000001 10 0--.-- ..................     \
                 001110 ..... ..... ................     @PLS_D
+
+### Prefixed No-operation Instruction
+
+@PNOP           000001 11 0000-- 000000000000000000     \
+                ................................
+
+{
+  [
+    ## Invalid suffixes: Branch instruction
+    # bc[l][a]
+    INVALID     ................................        \
+                010000--------------------------        @PNOP
+    # b[l][a]
+    INVALID     ................................        \
+                010010--------------------------        @PNOP
+    # bclr[l]
+    INVALID     ................................        \
+                010011---------------0000010000-        @PNOP
+    # bcctr[l]
+    INVALID     ................................        \
+                010011---------------1000010000-        @PNOP
+    # bctar[l]
+    INVALID     ................................        \
+                010011---------------1000110000-        @PNOP
+
+    ## Invalid suffixes: rfebb
+    INVALID     ................................        \
+                010011---------------0010010010-        @PNOP
+
+    ## Invalid suffixes: context synchronizing other than isync
+    # sc
+    INVALID     ................................        \
+                010001------------------------1-        @PNOP
+    # scv
+    INVALID     ................................        \
+                010001------------------------01        @PNOP
+    # rfscv
+    INVALID     ................................        \
+                010011---------------0001010010-        @PNOP
+    # rfid
+    INVALID     ................................        \
+                010011---------------0000010010-        @PNOP
+    # hrfid
+    INVALID     ................................        \
+                010011---------------0100010010-        @PNOP
+    # urfid
+    INVALID     ................................        \
+                010011---------------0100110010-        @PNOP
+    # stop
+    INVALID     ................................        \
+                010011---------------0101110010-        @PNOP
+    # mtmsr w/ L=0
+    INVALID     ................................        \
+                011111---------0-----0010010010-        @PNOP
+    # mtmsrd w/ L=0
+    INVALID     ................................        \
+                011111---------0-----0010110010-        @PNOP
+
+    ## Invalid suffixes: Service Processor Attention
+    INVALID     ................................        \
+                000000----------------100000000-        @PNOP
+  ]
+
+  ## Valid suffixes
+  PNOP          ................................        \
+                --------------------------------        @PNOP
+}

target/ppc/translate/fixedpoint-impl.c.inc

@@ -60,3 +60,14 @@ static bool trans_ADDIS(DisasContext *ctx, arg_D *a)
     a->si <<= 16;
     return trans_ADDI(ctx, a);
 }
+
+static bool trans_INVALID(DisasContext *ctx, arg_INVALID *a)
+{
+    gen_invalid(ctx);
+    return true;
+}
+
+static bool trans_PNOP(DisasContext *ctx, arg_PNOP *a)
+{
+    return true;
+}