[RFC PATCH 07/34] target/riscv: Combine mcyclecfg and mcyclecfgh

[Anton Johansson via]

According to version 20250508 of the privileged specification, mcyclecfg
is a 64-bit register and mcyclecfgh refers to the top 32 bits of this
register when XLEN == 32.  No real advantage is gained by keeping
them separate, and combining them allows for slight simplification.

Signed-off-by: Anton Johansson <a...@rev.ng>
---
 target/riscv/cpu.h |  3 +--
 target/riscv/csr.c | 28 +++++++++++++++++-----------
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index f0f4d71fdf..4b80daf117 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -419,8 +419,7 @@ struct CPUArchState {
     uint32_t mcountinhibit;
 
     /* PMU cycle & instret privilege mode filtering */
-    target_ulong mcyclecfg;
-    target_ulong mcyclecfgh;
+    uint64_t mcyclecfg;
     target_ulong minstretcfg;
     target_ulong minstretcfgh;
 
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 35f296954f..867f8efe83 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -1061,7 +1061,8 @@ static RISCVException read_hpmcounterh(CPURISCVState 
*env, int csrno,
 static RISCVException read_mcyclecfg(CPURISCVState *env, int csrno,
                                      target_ulong *val)
 {
-    *val = env->mcyclecfg;
+    bool rv32 = riscv_cpu_mxl(env) == MXL_RV32;
+    *val = extract64(env->mcyclecfg, 0, rv32 ? 32 : 64);
     return RISCV_EXCP_NONE;
 }
 
@@ -1071,7 +1072,7 @@ static RISCVException write_mcyclecfg(CPURISCVState *env, 
int csrno,
     uint64_t inh_avail_mask;
 
     if (riscv_cpu_mxl(env) == MXL_RV32) {
-        env->mcyclecfg = val;
+        env->mcyclecfg = deposit64(env->mcyclecfg, 0, 32, val);
     } else {
         /* Set xINH fields if priv mode supported */
         inh_avail_mask = ~MHPMEVENT_FILTER_MASK | MCYCLECFG_BIT_MINH;
@@ -1090,7 +1091,7 @@ static RISCVException write_mcyclecfg(CPURISCVState *env, 
int csrno,
 static RISCVException read_mcyclecfgh(CPURISCVState *env, int csrno,
                                       target_ulong *val)
 {
-    *val = env->mcyclecfgh;
+    *val = extract64(env->mcyclecfg, 32, 32);
     return RISCV_EXCP_NONE;
 }
 
@@ -1108,7 +1109,7 @@ static RISCVException write_mcyclecfgh(CPURISCVState 
*env, int csrno,
     inh_avail_mask |= (riscv_has_ext(env, RVH) &&
                        riscv_has_ext(env, RVS)) ? MCYCLECFGH_BIT_VSINH : 0;
 
-    env->mcyclecfgh = val & inh_avail_mask;
+    env->mcyclecfg = deposit64(env->mcyclecfg, 32, 32, val & inh_avail_mask);
     return RISCV_EXCP_NONE;
 }
 
@@ -1247,8 +1248,7 @@ static target_ulong 
riscv_pmu_ctr_get_fixed_counters_val(CPURISCVState *env,
     g_assert(rv32 || !upper_half);
 
     if (counter_idx == 0) {
-        cfg_val = rv32 ? ((uint64_t)env->mcyclecfgh << 32) :
-                  env->mcyclecfg;
+        cfg_val = env->mcyclecfg;
     } else if (counter_idx == 2) {
         cfg_val = rv32 ? ((uint64_t)env->minstretcfgh << 32) :
                   env->minstretcfg;
@@ -1522,8 +1522,12 @@ static int rmw_cd_mhpmeventh(CPURISCVState *env, int 
evt_index,
 }
 
 static int rmw_cd_ctr_cfg(CPURISCVState *env, int cfg_index, target_ulong *val,
-                            target_ulong new_val, target_ulong wr_mask)
+                          target_ulong new_val, uint64_t wr_mask)
 {
+    /*
+     * wr_mask is 64-bit so upper 32 bits of mcyclecfg and minstretcfg
+     * are retained.
+     */
     switch (cfg_index) {
     case 0:             /* CYCLECFG */
         if (wr_mask) {
@@ -1549,8 +1553,9 @@ static int rmw_cd_ctr_cfg(CPURISCVState *env, int 
cfg_index, target_ulong *val,
 }
 
 static int rmw_cd_ctr_cfgh(CPURISCVState *env, int cfg_index, target_ulong 
*val,
-                            target_ulong new_val, target_ulong wr_mask)
+                           target_ulong new_val, target_ulong wr_mask)
 {
+    uint64_t cfgh;
 
     if (riscv_cpu_mxl(env) != MXL_RV32) {
         return RISCV_EXCP_ILLEGAL_INST;
@@ -1558,12 +1563,13 @@ static int rmw_cd_ctr_cfgh(CPURISCVState *env, int 
cfg_index, target_ulong *val,
 
     switch (cfg_index) {
     case 0:         /* CYCLECFGH */
+        cfgh = extract64(env->mcyclecfg, 32, 32);
         if (wr_mask) {
             wr_mask &= ~MCYCLECFGH_BIT_MINH;
-            env->mcyclecfgh = (new_val & wr_mask) |
-                              (env->mcyclecfgh & ~wr_mask);
+            cfgh = (new_val & wr_mask) | (cfgh & ~wr_mask);
+            env->mcyclecfg = deposit64(env->mcyclecfg, 32, 32, cfgh);
         } else {
-            *val = env->mcyclecfgh;
+            *val = cfgh;
         }
         break;
     case 2:          /* INSTRETCFGH */
-- 
2.51.0