target/arm: Implement SME2 ZERO ZT0

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250704142112.1018902-18-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/syndrome.h

@@ -80,6 +80,7 @@ typedef enum {
     SME_ET_Streaming,
     SME_ET_NotStreaming,
     SME_ET_InactiveZA,
+    SME_ET_InaccessibleZT0,
 } SMEExceptionType;
 
 #define ARM_EL_EC_LENGTH 6

target/arm/tcg/sme.decode

@@ -22,6 +22,7 @@
 ### SME Misc
 
 ZERO            11000000 00 001 00000000000 imm:8
+ZERO_zt0        11000000 01 001 00000000000 00000001
 
 ### SME Move into/from Array
 

target/arm/tcg/translate-sme.c

@@ -27,6 +27,19 @@
 
 #include "decode-sme.c.inc"
 
+static bool sme2_zt0_enabled_check(DisasContext *s)
+{
+    if (!sme_za_enabled_check(s)) {
+        return false;
+    }
+    if (s->zt0_excp_el) {
+        gen_exception_insn_el(s, 0, EXCP_UDEF,
+                              syn_smetrap(SME_ET_InaccessibleZT0, false),
+                              s->zt0_excp_el);
+        return false;
+    }
+    return true;
+}
 
 /*
  * Resolve tile.size[index] to a host pointer, where tile and index
@@ -130,6 +143,19 @@ static bool trans_ZERO(DisasContext *s, arg_ZERO *a)
     return true;
 }
 
+static bool trans_ZERO_zt0(DisasContext *s, arg_ZERO_zt0 *a)
+{
+    if (!dc_isar_feature(aa64_sme2, s)) {
+        return false;
+    }
+    if (sme_enabled_check(s) && sme2_zt0_enabled_check(s)) {
+        tcg_gen_gvec_dup_imm(MO_64, offsetof(CPUARMState, za_state.zt0),
+                             sizeof_field(CPUARMState, za_state.zt0),
+                             sizeof_field(CPUARMState, za_state.zt0), 0);
+    }
+    return true;
+}
+
 static bool trans_MOVA(DisasContext *s, arg_MOVA *a)
 {
     static gen_helper_gvec_4 * const h_fns[5] = {