target/riscv: Add Ssdbltrp CSRs handling

Add ext_ssdbltrp in RISCVCPUConfig and implement MSTATUS.SDT,
{H|M}ENVCFG.DTE and modify the availability of MTVAL2 based on the
presence of the Ssdbltrp ISA extension.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20250110125441.3208676-3-cleger@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.h

@@ -564,6 +564,7 @@ void riscv_cpu_set_virt_enabled(CPURISCVState *env, bool enable);
 int riscv_env_mmu_index(CPURISCVState *env, bool ifetch);
 bool cpu_get_fcfien(CPURISCVState *env);
 bool cpu_get_bcfien(CPURISCVState *env);
+bool riscv_env_smode_dbltrp_enabled(CPURISCVState *env, bool virt);
 G_NORETURN void  riscv_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
                                                MMUAccessType access_type,
                                                int mmu_idx, uintptr_t retaddr);

target/riscv/cpu_bits.h

@@ -555,6 +555,7 @@
 #define MSTATUS_TW          0x00200000 /* since: priv-1.10 */
 #define MSTATUS_TSR         0x00400000 /* since: priv-1.10 */
 #define MSTATUS_SPELP       0x00800000 /* zicfilp */
+#define MSTATUS_SDT         0x01000000
 #define MSTATUS_MPELP       0x020000000000 /* zicfilp */
 #define MSTATUS_GVA         0x4000000000ULL
 #define MSTATUS_MPV         0x8000000000ULL
@@ -587,6 +588,7 @@ typedef enum {
 #define SSTATUS_SUM         0x00040000 /* since: priv-1.10 */
 #define SSTATUS_MXR         0x00080000
 #define SSTATUS_SPELP       MSTATUS_SPELP   /* zicfilp */
+#define SSTATUS_SDT         MSTATUS_SDT
 
 #define SSTATUS64_UXL       0x0000000300000000ULL
 
@@ -782,12 +784,14 @@ typedef enum RISCVException {
 #define MENVCFG_CBCFE                      BIT(6)
 #define MENVCFG_CBZE                       BIT(7)
 #define MENVCFG_PMM                        (3ULL << 32)
+#define MENVCFG_DTE                        (1ULL << 59)
 #define MENVCFG_CDE                        (1ULL << 60)
 #define MENVCFG_ADUE                       (1ULL << 61)
 #define MENVCFG_PBMTE                      (1ULL << 62)
 #define MENVCFG_STCE                       (1ULL << 63)
 
 /* For RV32 */
+#define MENVCFGH_DTE                       BIT(27)
 #define MENVCFGH_ADUE                      BIT(29)
 #define MENVCFGH_PBMTE                     BIT(30)
 #define MENVCFGH_STCE                      BIT(31)
@@ -808,11 +812,13 @@ typedef enum RISCVException {
 #define HENVCFG_CBCFE                      MENVCFG_CBCFE
 #define HENVCFG_CBZE                       MENVCFG_CBZE
 #define HENVCFG_PMM                        MENVCFG_PMM
+#define HENVCFG_DTE                        MENVCFG_DTE
 #define HENVCFG_ADUE                       MENVCFG_ADUE
 #define HENVCFG_PBMTE                      MENVCFG_PBMTE
 #define HENVCFG_STCE                       MENVCFG_STCE
 
 /* For RV32 */
+#define HENVCFGH_DTE                        MENVCFGH_DTE
 #define HENVCFGH_ADUE                       MENVCFGH_ADUE
 #define HENVCFGH_PBMTE                      MENVCFGH_PBMTE
 #define HENVCFGH_STCE                       MENVCFGH_STCE

target/riscv/cpu_cfg.h

@@ -83,6 +83,7 @@ struct RISCVCPUConfig {
     bool ext_smcntrpmf;
     bool ext_smcsrind;
     bool ext_sscsrind;
+    bool ext_ssdbltrp;
     bool ext_svadu;
     bool ext_svinval;
     bool ext_svnapot;

target/riscv/cpu_helper.c

@@ -120,6 +120,19 @@ bool cpu_get_bcfien(CPURISCVState *env)
     }
 }
 
+bool riscv_env_smode_dbltrp_enabled(CPURISCVState *env, bool virt)
+{
+#ifdef CONFIG_USER_ONLY
+    return false;
+#else
+    if (virt) {
+        return (env->henvcfg & HENVCFG_DTE) != 0;
+    } else {
+        return (env->menvcfg & MENVCFG_DTE) != 0;
+    }
+#endif
+}
+
 void cpu_get_tb_cpu_state(CPURISCVState *env, vaddr *pc,
                           uint64_t *cs_base, uint32_t *pflags)
 {
@@ -691,6 +704,10 @@ void riscv_cpu_swap_hypervisor_regs(CPURISCVState *env)
 
     g_assert(riscv_has_ext(env, RVH));
 
+    if (riscv_env_smode_dbltrp_enabled(env, current_virt)) {
+        mstatus_mask |= MSTATUS_SDT;
+    }
+
     if (current_virt) {
         /* Current V=1 and we are about to change to V=0 */
         env->vsstatus = env->mstatus & mstatus_mask;

target/riscv/csr.c

@@ -680,6 +680,15 @@ static RISCVException aia_hmode32(CPURISCVState *env, int csrno)
     return hmode32(env, csrno);
 }
 
+static RISCVException dbltrp_hmode(CPURISCVState *env, int csrno)
+{
+    if (riscv_cpu_cfg(env)->ext_ssdbltrp) {
+        return RISCV_EXCP_NONE;
+    }
+
+    return hmode(env, csrno);
+}
+
 static RISCVException pmp(CPURISCVState *env, int csrno)
 {
     if (riscv_cpu_cfg(env)->pmp) {
@@ -1938,6 +1947,13 @@ static RISCVException write_mstatus(CPURISCVState *env, int csrno,
         mask |= MSTATUS_VS;
     }
 
+    if (riscv_env_smode_dbltrp_enabled(env, env->virt_enabled)) {
+        mask |= MSTATUS_SDT;
+        if ((val & MSTATUS_SDT) != 0) {
+            val &= ~MSTATUS_SIE;
+        }
+    }
+
     if (xl != MXL_RV32 || env->debugger) {
         if (riscv_has_ext(env, RVH)) {
             mask |= MSTATUS_MPV | MSTATUS_GVA;
@@ -2959,7 +2975,8 @@ static RISCVException write_menvcfg(CPURISCVState *env, int csrno,
         mask |= (cfg->ext_svpbmt ? MENVCFG_PBMTE : 0) |
                 (cfg->ext_sstc ? MENVCFG_STCE : 0) |
                 (cfg->ext_smcdeleg ? MENVCFG_CDE : 0) |
-                (cfg->ext_svadu ? MENVCFG_ADUE : 0);
+                (cfg->ext_svadu ? MENVCFG_ADUE : 0) |
+                (cfg->ext_ssdbltrp ? MENVCFG_DTE : 0);
 
         if (env_archcpu(env)->cfg.ext_zicfilp) {
             mask |= MENVCFG_LPE;
@@ -2973,6 +2990,10 @@ static RISCVException write_menvcfg(CPURISCVState *env, int csrno,
         if (env_archcpu(env)->cfg.ext_smnpm &&
             get_field(val, MENVCFG_PMM) != PMM_FIELD_RESERVED) {
             mask |= MENVCFG_PMM;
+	}
+
+        if ((val & MENVCFG_DTE) == 0) {
+            env->mstatus &= ~MSTATUS_SDT;
         }
     }
     env->menvcfg = (env->menvcfg & ~mask) | (val & mask);
@@ -2997,9 +3018,14 @@ static RISCVException write_menvcfgh(CPURISCVState *env, int csrno,
     uint64_t mask = (cfg->ext_svpbmt ? MENVCFG_PBMTE : 0) |
                     (cfg->ext_sstc ? MENVCFG_STCE : 0) |
                     (cfg->ext_svadu ? MENVCFG_ADUE : 0) |
-                    (cfg->ext_smcdeleg ? MENVCFG_CDE : 0);
+                    (cfg->ext_smcdeleg ? MENVCFG_CDE : 0) |
+                    (cfg->ext_ssdbltrp ? MENVCFG_DTE : 0);
     uint64_t valh = (uint64_t)val << 32;
 
+    if ((valh & MENVCFG_DTE) == 0) {
+        env->mstatus &= ~MSTATUS_SDT;
+    }
+
     env->menvcfg = (env->menvcfg & ~mask) | (valh & mask);
     write_henvcfgh(env, CSR_HENVCFGH, env->henvcfg >> 32);
 
@@ -3070,9 +3096,10 @@ static RISCVException read_henvcfg(CPURISCVState *env, int csrno,
      * henvcfg.pbmte is read_only 0 when menvcfg.pbmte = 0
      * henvcfg.stce is read_only 0 when menvcfg.stce = 0
      * henvcfg.adue is read_only 0 when menvcfg.adue = 0
+     * henvcfg.dte is read_only 0 when menvcfg.dte = 0
      */
-    *val = env->henvcfg & (~(HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE) |
+    *val = env->henvcfg & (~(HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE |
-                           env->menvcfg);
+                             HENVCFG_DTE) | env->menvcfg);
     return RISCV_EXCP_NONE;
 }
 
@@ -3088,7 +3115,8 @@ static RISCVException write_henvcfg(CPURISCVState *env, int csrno,
     }
 
     if (riscv_cpu_mxl(env) == MXL_RV64) {
-        mask |= env->menvcfg & (HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE);
+        mask |= env->menvcfg & (HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE |
+                                HENVCFG_DTE);
 
         if (env_archcpu(env)->cfg.ext_zicfilp) {
             mask |= HENVCFG_LPE;
@@ -3108,6 +3136,9 @@ static RISCVException write_henvcfg(CPURISCVState *env, int csrno,
     }
 
     env->henvcfg = val & mask;
+    if ((env->henvcfg & HENVCFG_DTE) == 0) {
+        env->vsstatus &= ~MSTATUS_SDT;
+    }
 
     return RISCV_EXCP_NONE;
 }
@@ -3122,8 +3153,8 @@ static RISCVException read_henvcfgh(CPURISCVState *env, int csrno,
         return ret;
     }
 
-    *val = (env->henvcfg & (~(HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE) |
+    *val = (env->henvcfg & (~(HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE |
-                            env->menvcfg)) >> 32;
+                              HENVCFG_DTE) | env->menvcfg)) >> 32;
     return RISCV_EXCP_NONE;
 }
 
@@ -3131,7 +3162,7 @@ static RISCVException write_henvcfgh(CPURISCVState *env, int csrno,
                                      target_ulong val)
 {
     uint64_t mask = env->menvcfg & (HENVCFG_PBMTE | HENVCFG_STCE |
-                                    HENVCFG_ADUE);
+                                    HENVCFG_ADUE | HENVCFG_DTE);
     uint64_t valh = (uint64_t)val << 32;
     RISCVException ret;
 
@@ -3139,8 +3170,10 @@ static RISCVException write_henvcfgh(CPURISCVState *env, int csrno,
     if (ret != RISCV_EXCP_NONE) {
         return ret;
     }
-
     env->henvcfg = (env->henvcfg & 0xFFFFFFFF) | (valh & mask);
+    if ((env->henvcfg & HENVCFG_DTE) == 0) {
+        env->vsstatus &= ~MSTATUS_SDT;
+    }
     return RISCV_EXCP_NONE;
 }
 
@@ -3594,6 +3627,9 @@ static RISCVException read_sstatus_i128(CPURISCVState *env, int csrno,
     if (env->xl != MXL_RV32 || env->debugger) {
         mask |= SSTATUS64_UXL;
     }
+    if (riscv_cpu_cfg(env)->ext_ssdbltrp) {
+        mask |= SSTATUS_SDT;
+    }
 
     if (env_archcpu(env)->cfg.ext_zicfilp) {
         mask |= SSTATUS_SPELP;
@@ -3614,7 +3650,9 @@ static RISCVException read_sstatus(CPURISCVState *env, int csrno,
     if (env_archcpu(env)->cfg.ext_zicfilp) {
         mask |= SSTATUS_SPELP;
     }
-
+    if (riscv_cpu_cfg(env)->ext_ssdbltrp) {
+        mask |= SSTATUS_SDT;
+    }
     /* TODO: Use SXL not MXL. */
     *val = add_status_sd(riscv_cpu_mxl(env), env->mstatus & mask);
     return RISCV_EXCP_NONE;
@@ -3634,7 +3672,9 @@ static RISCVException write_sstatus(CPURISCVState *env, int csrno,
     if (env_archcpu(env)->cfg.ext_zicfilp) {
         mask |= SSTATUS_SPELP;
     }
-
+    if (riscv_cpu_cfg(env)->ext_ssdbltrp) {
+        mask |= SSTATUS_SDT;
+    }
     target_ulong newval = (env->mstatus & ~mask) | (val & mask);
     return write_mstatus(env, CSR_MSTATUS, newval);
 }
@@ -4751,6 +4791,13 @@ static RISCVException write_vsstatus(CPURISCVState *env, int csrno,
     if ((val & VSSTATUS64_UXL) == 0) {
         mask &= ~VSSTATUS64_UXL;
     }
+    if ((env->henvcfg & HENVCFG_DTE)) {
+        if ((val & SSTATUS_SDT) != 0) {
+            val &= ~SSTATUS_SIE;
+        }
+    } else {
+        val &= ~SSTATUS_SDT;
+    }
     env->vsstatus = (env->vsstatus & ~mask) | (uint64_t)val;
     return RISCV_EXCP_NONE;
 }
@@ -5698,7 +5745,7 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_VSATP]       = { "vsatp",       hmode,   read_vsatp,    write_vsatp,
                           .min_priv_ver = PRIV_VERSION_1_12_0                },
 
-    [CSR_MTVAL2]      = { "mtval2",      hmode,   read_mtval2,   write_mtval2,
+    [CSR_MTVAL2]      = { "mtval2", dbltrp_hmode, read_mtval2, write_mtval2,
                           .min_priv_ver = PRIV_VERSION_1_12_0                },
     [CSR_MTINST]      = { "mtinst",      hmode,   read_mtinst,   write_mtinst,
                           .min_priv_ver = PRIV_VERSION_1_12_0                },