target/riscv: Separate priv from mmu_idx

Currently it's assumed the 2 low bits of mmu_idx map to privilege mode,
this assumption won't last as we are about to add more mmu_idx. Here an
individual priv field is added into TB_FLAGS.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Fei Wu <fei2.wu@intel.com>
Message-Id: <20230324054154.414846-2-fei2.wu@intel.com>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Tested-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-Id: <20230325105429.1142530-7-richard.henderson@linaro.org>
Message-Id: <20230412114333.118895-7-richard.henderson@linaro.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.h

@@ -629,7 +629,6 @@ G_NORETURN void riscv_raise_exception(CPURISCVState *env,
 target_ulong riscv_cpu_get_fflags(CPURISCVState *env);
 void riscv_cpu_set_fflags(CPURISCVState *env, target_ulong);
 
-#define TB_FLAGS_PRIV_MMU_MASK                3
 #define TB_FLAGS_PRIV_HYP_ACCESS_MASK   (1 << 2)
 
 #include "exec/cpu-all.h"
@@ -656,6 +655,7 @@ FIELD(TB_FLAGS, ITRIGGER, 22, 1)
 /* Virtual mode enabled */
 FIELD(TB_FLAGS, VIRT_ENABLED, 23, 1)
 FIELD(TB_FLAGS, VSTART_EQ_ZERO, 24, 1)
+FIELD(TB_FLAGS, PRIV, 25, 2)
 
 #ifdef TARGET_RISCV32
 #define riscv_cpu_mxl(env)  ((void)(env), MXL_RV32)

target/riscv/cpu_helper.c

@@ -83,6 +83,8 @@ void cpu_get_tb_cpu_state(CPURISCVState *env, target_ulong *pc,
     fs = EXT_STATUS_DIRTY;
     vs = EXT_STATUS_DIRTY;
 #else
+    flags = FIELD_DP32(flags, TB_FLAGS, PRIV, env->priv);
+
     flags |= cpu_mmu_index(env, 0);
     fs = get_field(env->mstatus, MSTATUS_FS);
     vs = get_field(env->mstatus, MSTATUS_VS);
@@ -751,7 +753,7 @@ static int get_physical_address(CPURISCVState *env, hwaddr *physical,
      */
     MemTxResult res;
     MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
-    int mode = mmu_idx & TB_FLAGS_PRIV_MMU_MASK;
+    int mode = env->priv;
     bool use_background = false;
     hwaddr ppn;
     int napot_bits = 0;

target/riscv/insn_trans/trans_privileged.c.inc

@@ -52,7 +52,7 @@ static bool trans_ebreak(DisasContext *ctx, arg_ebreak *a)
      * that no exception will be raised when fetching them.
      */
 
-    if (semihosting_enabled(ctx->mem_idx < PRV_S) &&
+    if (semihosting_enabled(ctx->priv == PRV_U) &&
         (pre_addr & TARGET_PAGE_MASK) == (post_addr & TARGET_PAGE_MASK)) {
         pre    = opcode_at(&ctx->base, pre_addr);
         ebreak = opcode_at(&ctx->base, ebreak_addr);

target/riscv/insn_trans/trans_xthead.c.inc

@@ -263,25 +263,13 @@ static bool trans_th_tst(DisasContext *ctx, arg_th_tst *a)
 
 /* XTheadCmo */
 
-static inline int priv_level(DisasContext *ctx)
-{
-#ifdef CONFIG_USER_ONLY
-    return PRV_U;
-#else
-     /* Priv level is part of mem_idx. */
-    return ctx->mem_idx & TB_FLAGS_PRIV_MMU_MASK;
-#endif
-}
-
 /* Test if priv level is M, S, or U (cannot fail). */
 #define REQUIRE_PRIV_MSU(ctx)
 
 /* Test if priv level is M or S. */
 #define REQUIRE_PRIV_MS(ctx)                                    \
 do {                                                            \
-    int priv = priv_level(ctx);                                 \
+    if (ctx->priv == PRV_U) {                                   \
-    if (!(priv == PRV_M ||                                      \
-          priv == PRV_S)) {                                     \
         return false;                                           \
     }                                                           \
 } while (0)

target/riscv/translate.c

@@ -67,6 +67,7 @@ typedef struct DisasContext {
     RISCVExtStatus mstatus_fs;
     RISCVExtStatus mstatus_vs;
     uint32_t mem_idx;
+    uint32_t priv;
     /*
      * Remember the rounding mode encoded in the previous fp instruction,
      * which we have already installed into env->fp_status.  Or -1 for
@@ -1153,6 +1154,7 @@ static void riscv_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs)
     uint32_t tb_flags = ctx->base.tb->flags;
 
     ctx->pc_succ_insn = ctx->base.pc_first;
+    ctx->priv = FIELD_EX32(tb_flags, TB_FLAGS, PRIV);
     ctx->mem_idx = FIELD_EX32(tb_flags, TB_FLAGS, MEM_IDX);
     ctx->mstatus_fs = FIELD_EX32(tb_flags, TB_FLAGS, FS);
     ctx->mstatus_vs = FIELD_EX32(tb_flags, TB_FLAGS, VS);