target/riscv: Set [m|s]tval for both illegal and virtual instruction traps

Currently, the [m|s]tval CSRs are set with trapping instruction encoding
only for illegal instruction traps taken at the time of instruction
decoding.

In RISC-V world, a valid instructions might also trap as illegal or
virtual instruction based to trapping bits in various CSRs (such as
mstatus.TVM or hstatus.VTVM).

We improve setting of [m|s]tval CSRs for all types of illegal and
virtual instruction traps.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20220511144528.393530-4-apatel@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.c

@@ -406,6 +406,7 @@ void restore_state_to_opc(CPURISCVState *env, TranslationBlock *tb,
     } else {
         env->pc = data[0];
     }
+    env->bins = data[1];
 }
 
 static void riscv_cpu_reset(DeviceState *dev)
@@ -445,6 +446,7 @@ static void riscv_cpu_reset(DeviceState *dev)
     env->mcause = 0;
     env->miclaim = MIP_SGEIP;
     env->pc = env->resetvec;
+    env->bins = 0;
     env->two_stage_lookup = false;
 
     /* Initialized default priorities of local interrupts. */

target/riscv/cpu.h

@@ -30,6 +30,12 @@
 
 #define TCG_GUEST_DEFAULT_MO 0
 
+/*
+ * RISC-V-specific extra insn start words:
+ * 1: Original instruction opcode
+ */
+#define TARGET_INSN_START_EXTRA_WORDS 1
+
 #define TYPE_RISCV_CPU "riscv-cpu"
 
 #define RISCV_CPU_TYPE_SUFFIX "-" TYPE_RISCV_CPU
@@ -140,7 +146,7 @@ struct CPUArchState {
     target_ulong frm;
 
     target_ulong badaddr;
-    uint32_t bins;
+    target_ulong bins;
 
     target_ulong guest_phys_fault_addr;
 

target/riscv/cpu_helper.c

@@ -1371,6 +1371,7 @@ void riscv_cpu_do_interrupt(CPUState *cs)
             tval = env->badaddr;
             break;
         case RISCV_EXCP_ILLEGAL_INST:
+        case RISCV_EXCP_VIRT_INSTRUCTION_FAULT:
             tval = env->bins;
             break;
         default:

target/riscv/translate.c

@@ -107,6 +107,8 @@ typedef struct DisasContext {
     /* PointerMasking extension */
     bool pm_mask_enabled;
     bool pm_base_enabled;
+    /* TCG of the current insn_start */
+    TCGOp *insn_start;
 } DisasContext;
 
 static inline bool has_ext(DisasContext *ctx, uint32_t ext)
@@ -236,9 +238,6 @@ static void generate_exception_mtval(DisasContext *ctx, int excp)
 
 static void gen_exception_illegal(DisasContext *ctx)
 {
-    tcg_gen_st_i32(tcg_constant_i32(ctx->opcode), cpu_env,
-                   offsetof(CPURISCVState, bins));
-
     generate_exception(ctx, RISCV_EXCP_ILLEGAL_INST);
 }
 
@@ -1017,6 +1016,13 @@ static uint32_t opcode_at(DisasContextBase *dcbase, target_ulong pc)
 /* Include decoders for factored-out extensions */
 #include "decode-XVentanaCondOps.c.inc"
 
+static inline void decode_save_opc(DisasContext *ctx, target_ulong opc)
+{
+    assert(ctx->insn_start != NULL);
+    tcg_set_insn_start_param(ctx->insn_start, 1, opc);
+    ctx->insn_start = NULL;
+}
+
 static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode)
 {
     /*
@@ -1033,6 +1039,7 @@ static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode)
 
     /* Check for compressed insn */
     if (extract16(opcode, 0, 2) != 3) {
+        decode_save_opc(ctx, opcode);
         if (!has_ext(ctx, RVC)) {
             gen_exception_illegal(ctx);
         } else {
@@ -1047,6 +1054,7 @@ static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode)
         opcode32 = deposit32(opcode32, 16, 16,
                              translator_lduw(env, &ctx->base,
                                              ctx->base.pc_next + 2));
+        decode_save_opc(ctx, opcode32);
         ctx->opcode = opcode32;
         ctx->pc_succ_insn = ctx->base.pc_next + 4;
 
@@ -1113,7 +1121,8 @@ static void riscv_tr_insn_start(DisasContextBase *dcbase, CPUState *cpu)
 {
     DisasContext *ctx = container_of(dcbase, DisasContext, base);
 
-    tcg_gen_insn_start(ctx->base.pc_next);
+    tcg_gen_insn_start(ctx->base.pc_next, 0);
+    ctx->insn_start = tcg_last_op();
 }
 
 static void riscv_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)