On 2024/10/14 19:22, Clément Léger wrote:
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 <cle...@rivosinc.com>
Reviewed-by: Alistair Francis <alistair.fran...@wdc.com>
---
  target/riscv/cpu.h        |  1 +
  target/riscv/cpu_bits.h   |  6 ++++++
  target/riscv/cpu_cfg.h    |  1 +
  target/riscv/cpu_helper.c | 20 +++++++++++++++++
  target/riscv/csr.c        | 45 ++++++++++++++++++++++++++++++---------
  5 files changed, 63 insertions(+), 10 deletions(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index a84e719d3f..ee984bf270 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -553,6 +553,7 @@ void riscv_cpu_set_geilen(CPURISCVState *env, target_ulong 
geilen);
  bool riscv_cpu_vector_enabled(CPURISCVState *env);
  void riscv_cpu_set_virt_enabled(CPURISCVState *env, bool enable);
  int riscv_env_mmu_index(CPURISCVState *env, bool ifetch);
+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);
diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index da1723496c..3a5588d4df 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -558,6 +558,7 @@
  #define MSTATUS_TVM         0x00100000 /* since: priv-1.10 */
  #define MSTATUS_TW          0x00200000 /* since: priv-1.10 */
  #define MSTATUS_TSR         0x00400000 /* since: priv-1.10 */
+#define MSTATUS_SDT         0x01000000
  #define MSTATUS_GVA         0x4000000000ULL
  #define MSTATUS_MPV         0x8000000000ULL
@@ -588,6 +589,7 @@ typedef enum {
  #define SSTATUS_XS          0x00018000
  #define SSTATUS_SUM         0x00040000 /* since: priv-1.10 */
  #define SSTATUS_MXR         0x00080000
+#define SSTATUS_SDT         0x01000000
#define SSTATUS64_UXL 0x0000000300000000ULL @@ -777,11 +779,13 @@ typedef enum RISCVException {
  #define MENVCFG_CBIE                       (3UL << 4)
  #define MENVCFG_CBCFE                      BIT(6)
  #define MENVCFG_CBZE                       BIT(7)
+#define MENVCFG_DTE                        (1ULL << 59)
  #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)
@@ -795,11 +799,13 @@ typedef enum RISCVException {
  #define HENVCFG_CBIE                       MENVCFG_CBIE
  #define HENVCFG_CBCFE                      MENVCFG_CBCFE
  #define HENVCFG_CBZE                       MENVCFG_CBZE
+#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
diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
index ae2a945b5f..dd804f95d4 100644
--- a/target/riscv/cpu_cfg.h
+++ b/target/riscv/cpu_cfg.h
@@ -77,6 +77,7 @@ struct RISCVCPUConfig {
      bool ext_smstateen;
      bool ext_sstc;
      bool ext_smcntrpmf;
+    bool ext_ssdbltrp;
      bool ext_svadu;
      bool ext_svinval;
      bool ext_svnapot;
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 9d0400035f..77e7736d8a 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -63,6 +63,22 @@ int riscv_env_mmu_index(CPURISCVState *env, bool ifetch)
  #endif
  }
+bool riscv_env_smode_dbltrp_enabled(CPURISCVState *env, bool virt)
+{
+#ifdef CONFIG_USER_ONLY
+    return false;
+#else
+    if (!riscv_cpu_cfg(env)->ext_ssdbltrp) {
+        return false;
+    }

As we have guard the write to henvcfg and menvcfg by ext_ssdbltrp, I think it is enough only check henvcfg or menvcfg.

The only miss is we don't guard the writhe to henvcfgh. I think we can add the guard there.

+    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)
  {
@@ -562,6 +578,10 @@ 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;
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index e5de72453c..d8280ec956 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -540,6 +540,15 @@ 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) {
@@ -1402,7 +1411,7 @@ static const target_ulong vs_delegable_excps = 
DELEGABLE_EXCPS &
        (1ULL << (RISCV_EXCP_STORE_GUEST_AMO_ACCESS_FAULT)));
  static const target_ulong sstatus_v1_10_mask = SSTATUS_SIE | SSTATUS_SPIE |
      SSTATUS_UIE | SSTATUS_UPIE | SSTATUS_SPP | SSTATUS_FS | SSTATUS_XS |
-    SSTATUS_SUM | SSTATUS_MXR | SSTATUS_VS;
+    SSTATUS_SUM | SSTATUS_MXR | SSTATUS_VS | SSTATUS_SDT;
This breaks  the v_1_10 constraint, as it is not part of 1.10 specification.
/*
   * Spec allows for bits 13:63 to be either read-only or writable.
@@ -1600,6 +1609,14 @@ 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) {
+            mstatus &= ~MSTATUS_SIE;
No need to clean it, if MSTATUS_SIE will be cleaned in val.
+            val &= ~MSTATUS_SIE;
+        }
+    }
+
I think we should also consider vsstatus for SIE field, as write_vsstatus doesn't fall through to write_mstatus.
      if (xl != MXL_RV32 || env->debugger) {
          if (riscv_has_ext(env, RVH)) {
              mask |= MSTATUS_MPV | MSTATUS_GVA;
@@ -2354,7 +2371,8 @@ static RISCVException write_menvcfg(CPURISCVState *env, 
int csrno,
      if (riscv_cpu_mxl(env) == MXL_RV64) {
          mask |= (cfg->ext_svpbmt ? MENVCFG_PBMTE : 0) |
                  (cfg->ext_sstc ? MENVCFG_STCE : 0) |
-                (cfg->ext_svadu ? MENVCFG_ADUE : 0);
+                (cfg->ext_svadu ? MENVCFG_ADUE : 0) |
+                (cfg->ext_ssdbltrp ? MENVCFG_DTE : 0);
      }
      env->menvcfg = (env->menvcfg & ~mask) | (val & mask);
@@ -2374,7 +2392,8 @@ static RISCVException write_menvcfgh(CPURISCVState *env, int csrno,
      const RISCVCPUConfig *cfg = riscv_cpu_cfg(env);
      uint64_t mask = (cfg->ext_svpbmt ? MENVCFG_PBMTE : 0) |
                      (cfg->ext_sstc ? MENVCFG_STCE : 0) |
-                    (cfg->ext_svadu ? MENVCFG_ADUE : 0);
+                    (cfg->ext_svadu ? MENVCFG_ADUE : 0) |
+                    (cfg->ext_ssdbltrp ? MENVCFG_DTE : 0);
      uint64_t valh = (uint64_t)val << 32;
env->menvcfg = (env->menvcfg & ~mask) | (valh & mask);
@@ -2425,9 +2444,10 @@ 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) |
-                           env->menvcfg);
+    *val = env->henvcfg & (~(HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE |
+                             HENVCFG_DTE) | env->menvcfg);
      return RISCV_EXCP_NONE;
  }
@@ -2435,6 +2455,7 @@ static RISCVException write_henvcfg(CPURISCVState *env, int csrno,
                                      target_ulong val)
  {
      uint64_t mask = HENVCFG_FIOM | HENVCFG_CBIE | HENVCFG_CBCFE | 
HENVCFG_CBZE;
+    uint64_t menvcfg_mask;
      RISCVException ret;
ret = smstateen_acc_ok(env, 0, SMSTATEEN0_HSENVCFG);
@@ -2443,7 +2464,11 @@ static RISCVException write_henvcfg(CPURISCVState *env, 
int csrno,
      }
if (riscv_cpu_mxl(env) == MXL_RV64) {
-        mask |= env->menvcfg & (HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE);
+        menvcfg_mask = HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE;
+        if (riscv_cpu_cfg(env)->ext_ssdbltrp) {
+            menvcfg_mask |= HENVCFG_DTE;
+        }
+        mask |= env->menvcfg & menvcfg_mask;
      }
env->henvcfg = (env->henvcfg & ~mask) | (val & mask);
@@ -2461,8 +2486,8 @@ static RISCVException read_henvcfgh(CPURISCVState *env, 
int csrno,
          return ret;
      }
- *val = (env->henvcfg & (~(HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE) |
-                            env->menvcfg)) >> 32;
+    *val = (env->henvcfg & (~(HENVCFG_PBMTE | HENVCFG_STCE | HENVCFG_ADUE |
+                              HENVCFG_DTE) | env->menvcfg)) >> 32;
      return RISCV_EXCP_NONE;
  }
@@ -2470,7 +2495,7 @@ 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);

Add the ssdbltrp guard here.

Thanks,
Zhiwei

      uint64_t valh = (uint64_t)val << 32;
      RISCVException ret;
@@ -5246,7 +5271,7 @@ 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                
},

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