[RFC PATCH 09/34] target/riscv: Combine mhpmcounter and mhpmcounterh

Anton Johansson via posted 34 patches 4 days, 8 hours ago
Maintainers: Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <alistair.francis@wdc.com>, Weiwei Li <liwei1518@gmail.com>, Daniel Henrique Barboza <dbarboza@ventanamicro.com>, Liu Zhiwei <zhiwei_liu@linux.alibaba.com>, Laurent Vivier <laurent@vivier.eu>, Christoph Muellner <christoph.muellner@vrull.eu>
[RFC PATCH 09/34] target/riscv: Combine mhpmcounter and mhpmcounterh
Posted by Anton Johansson via 4 days, 8 hours ago
According to version 20250508 of the privileged specification,
mhpmconter is a 64-bit register and mhpmcounterh refers to the top
32 bits of this register when XLEN == 32.  No real advantage is
gained by keeping them separate, and combining allows for slight
simplification.

Signed-off-by: Anton Johansson <anjo@rev.ng>
---
 target/riscv/cpu.h     |   8 +--
 target/riscv/csr.c     |  74 +++++++++++++--------------
 target/riscv/machine.c |   6 +--
 target/riscv/pmu.c     | 111 +++++++++++------------------------------
 4 files changed, 68 insertions(+), 131 deletions(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 81719813cf..b0d6e74ea3 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -195,13 +195,9 @@ FIELD(VTYPE, RESERVED, 10, sizeof(target_ulong) * 8 - 11)
 
 typedef struct PMUCTRState {
     /* Current value of a counter */
-    target_ulong mhpmcounter_val;
-    /* Current value of a counter in RV32 */
-    target_ulong mhpmcounterh_val;
+    uint64_t mhpmcounter_val;
     /* Snapshot values of counter */
-    target_ulong mhpmcounter_prev;
-    /* Snapshort value of a counter in RV32 */
-    target_ulong mhpmcounterh_prev;
+    uint64_t mhpmcounter_prev;
     /* Value beyond UINT32_MAX/UINT64_MAX before overflow interrupt trigger */
     target_ulong irq_overflow_left;
 } PMUCTRState;
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 4d232b062b..f29a3c9991 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -1299,24 +1299,27 @@ static RISCVException riscv_pmu_write_ctr(CPURISCVState *env, target_ulong val,
                                           uint32_t ctr_idx)
 {
     PMUCTRState *counter = &env->pmu_ctrs[ctr_idx];
-    uint64_t mhpmctr_val = val;
+    bool rv32 = riscv_cpu_mxl(env) == MXL_RV32;
+    int deposit_size = rv32 ? 32 : 64;
+    uint64_t ctr;
+
+    counter->mhpmcounter_val = deposit64(counter->mhpmcounter_val,
+                                         0, deposit_size, val);
 
-    counter->mhpmcounter_val = val;
     if (!get_field(env->mcountinhibit, BIT(ctr_idx)) &&
         (riscv_pmu_ctr_monitor_cycles(env, ctr_idx) ||
          riscv_pmu_ctr_monitor_instructions(env, ctr_idx))) {
-        counter->mhpmcounter_prev = riscv_pmu_ctr_get_fixed_counters_val(env,
-                                                                ctr_idx, false);
+        ctr = riscv_pmu_ctr_get_fixed_counters_val(env, ctr_idx, false);
+        counter->mhpmcounter_prev = deposit64(counter->mhpmcounter_prev,
+                                              0, deposit_size, ctr);
         if (ctr_idx > 2) {
-            if (riscv_cpu_mxl(env) == MXL_RV32) {
-                mhpmctr_val = mhpmctr_val |
-                              ((uint64_t)counter->mhpmcounterh_val << 32);
-            }
-            riscv_pmu_setup_timer(env, mhpmctr_val, ctr_idx);
+            riscv_pmu_setup_timer(env, counter->mhpmcounter_val, ctr_idx);
         }
      } else {
         /* Other counters can keep incrementing from the given value */
-        counter->mhpmcounter_prev = val;
+        counter->mhpmcounter_prev = deposit64(counter->mhpmcounter_prev,
+                                              0, deposit_size, val);
+
     }
 
     return RISCV_EXCP_NONE;
@@ -1326,21 +1329,22 @@ static RISCVException riscv_pmu_write_ctrh(CPURISCVState *env, target_ulong val,
                                           uint32_t ctr_idx)
 {
     PMUCTRState *counter = &env->pmu_ctrs[ctr_idx];
-    uint64_t mhpmctr_val = counter->mhpmcounter_val;
-    uint64_t mhpmctrh_val = val;
+    uint64_t ctrh;
 
-    counter->mhpmcounterh_val = val;
-    mhpmctr_val = mhpmctr_val | (mhpmctrh_val << 32);
+    counter->mhpmcounter_val = deposit64(counter->mhpmcounter_val,
+                                         32, 32, val);
     if (!get_field(env->mcountinhibit, BIT(ctr_idx)) &&
         (riscv_pmu_ctr_monitor_cycles(env, ctr_idx) ||
          riscv_pmu_ctr_monitor_instructions(env, ctr_idx))) {
-        counter->mhpmcounterh_prev = riscv_pmu_ctr_get_fixed_counters_val(env,
-                                                                 ctr_idx, true);
+        ctrh = riscv_pmu_ctr_get_fixed_counters_val(env, ctr_idx, true);
+        counter->mhpmcounter_prev = deposit64(counter->mhpmcounter_prev,
+                                              32, 32, ctrh);
         if (ctr_idx > 2) {
-            riscv_pmu_setup_timer(env, mhpmctr_val, ctr_idx);
+            riscv_pmu_setup_timer(env, counter->mhpmcounter_val, ctr_idx);
         }
     } else {
-        counter->mhpmcounterh_prev = val;
+        counter->mhpmcounter_prev = deposit64(counter->mhpmcounter_prev,
+                                              32, 32, val);
     }
 
     return RISCV_EXCP_NONE;
@@ -1363,13 +1367,17 @@ static RISCVException write_mhpmcounterh(CPURISCVState *env, int csrno,
 }
 
 RISCVException riscv_pmu_read_ctr(CPURISCVState *env, target_ulong *val,
-                                         bool upper_half, uint32_t ctr_idx)
+                                  bool upper_half, uint32_t ctr_idx)
 {
     PMUCTRState *counter = &env->pmu_ctrs[ctr_idx];
-    target_ulong ctr_prev = upper_half ? counter->mhpmcounterh_prev :
-                                         counter->mhpmcounter_prev;
-    target_ulong ctr_val = upper_half ? counter->mhpmcounterh_val :
-                                        counter->mhpmcounter_val;
+    bool rv32 = riscv_cpu_mxl(env) == MXL_RV32;
+    int start = upper_half ? 32 : 0;
+    int length = rv32 ? 32 : 64;
+    uint64_t ctr_prev = extract64(counter->mhpmcounter_prev, start, length);
+    uint64_t ctr_val  = extract64(counter->mhpmcounter_val, start, length);
+
+    /* Ensure upper_half is only set for XLEN == 32 */
+    g_assert(rv32 || !upper_half);
 
     if (get_field(env->mcountinhibit, BIT(ctr_idx))) {
         /*
@@ -2994,6 +3002,7 @@ static RISCVException write_mcountinhibit(CPURISCVState *env, int csrno,
     uint32_t present_ctrs = cpu->pmu_avail_ctrs | COUNTEREN_CY | COUNTEREN_IR;
     target_ulong updated_ctrs = (env->mcountinhibit ^ val) & present_ctrs;
     uint64_t mhpmctr_val, prev_count, curr_count;
+    uint64_t ctrh;
 
     /* WARL register - disable unavailable counters; TM bit is always 0 */
     env->mcountinhibit = val & present_ctrs;
@@ -3012,17 +3021,13 @@ static RISCVException write_mcountinhibit(CPURISCVState *env, int csrno,
             counter->mhpmcounter_prev =
                 riscv_pmu_ctr_get_fixed_counters_val(env, cidx, false);
             if (riscv_cpu_mxl(env) == MXL_RV32) {
-                counter->mhpmcounterh_prev =
-                    riscv_pmu_ctr_get_fixed_counters_val(env, cidx, true);
+                ctrh = riscv_pmu_ctr_get_fixed_counters_val(env, cidx, true);
+                counter->mhpmcounter_prev = deposit64(counter->mhpmcounter_prev,
+                                                      32, 32, ctrh);
             }
 
             if (cidx > 2) {
-                mhpmctr_val = counter->mhpmcounter_val;
-                if (riscv_cpu_mxl(env) == MXL_RV32) {
-                    mhpmctr_val = mhpmctr_val |
-                            ((uint64_t)counter->mhpmcounterh_val << 32);
-                }
-                riscv_pmu_setup_timer(env, mhpmctr_val, cidx);
+                riscv_pmu_setup_timer(env, counter->mhpmcounter_val, cidx);
             }
         } else {
             curr_count = riscv_pmu_ctr_get_fixed_counters_val(env, cidx, false);
@@ -3034,18 +3039,11 @@ static RISCVException write_mcountinhibit(CPURISCVState *env, int csrno,
                     riscv_pmu_ctr_get_fixed_counters_val(env, cidx, true);
 
                 curr_count = curr_count | (tmp << 32);
-                mhpmctr_val = mhpmctr_val |
-                    ((uint64_t)counter->mhpmcounterh_val << 32);
-                prev_count = prev_count |
-                    ((uint64_t)counter->mhpmcounterh_prev << 32);
             }
 
             /* Adjust the counter for later reads. */
             mhpmctr_val = curr_count - prev_count + mhpmctr_val;
             counter->mhpmcounter_val = mhpmctr_val;
-            if (riscv_cpu_mxl(env) == MXL_RV32) {
-                counter->mhpmcounterh_val = mhpmctr_val >> 32;
-            }
         }
     }
 
diff --git a/target/riscv/machine.c b/target/riscv/machine.c
index c476bb0089..7b00cb4804 100644
--- a/target/riscv/machine.c
+++ b/target/riscv/machine.c
@@ -338,10 +338,8 @@ static const VMStateDescription vmstate_pmu_ctr_state = {
     .minimum_version_id = 2,
     .needed = pmu_needed,
     .fields = (const VMStateField[]) {
-        VMSTATE_UINTTL(mhpmcounter_val, PMUCTRState),
-        VMSTATE_UINTTL(mhpmcounterh_val, PMUCTRState),
-        VMSTATE_UINTTL(mhpmcounter_prev, PMUCTRState),
-        VMSTATE_UINTTL(mhpmcounterh_prev, PMUCTRState),
+        VMSTATE_UINT64(mhpmcounter_val, PMUCTRState),
+        VMSTATE_UINT64(mhpmcounter_prev, PMUCTRState),
         VMSTATE_END_OF_LIST()
     }
 };
diff --git a/target/riscv/pmu.c b/target/riscv/pmu.c
index 273822e921..708f2ec7aa 100644
--- a/target/riscv/pmu.c
+++ b/target/riscv/pmu.c
@@ -101,82 +101,6 @@ static bool riscv_pmu_counter_enabled(RISCVCPU *cpu, uint32_t ctr_idx)
     }
 }
 
-static int riscv_pmu_incr_ctr_rv32(RISCVCPU *cpu, uint32_t ctr_idx)
-{
-    CPURISCVState *env = &cpu->env;
-    target_ulong max_val = UINT32_MAX;
-    PMUCTRState *counter = &env->pmu_ctrs[ctr_idx];
-    bool virt_on = env->virt_enabled;
-
-    /* Privilege mode filtering */
-    if ((env->priv == PRV_M &&
-        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_MINH)) ||
-        (env->priv == PRV_S && virt_on &&
-        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_VSINH)) ||
-        (env->priv == PRV_U && virt_on &&
-        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_VUINH)) ||
-        (env->priv == PRV_S && !virt_on &&
-        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_SINH)) ||
-        (env->priv == PRV_U && !virt_on &&
-        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_UINH))) {
-        return 0;
-    }
-
-    /* Handle the overflow scenario */
-    if (counter->mhpmcounter_val == max_val) {
-        if (counter->mhpmcounterh_val == max_val) {
-            counter->mhpmcounter_val = 0;
-            counter->mhpmcounterh_val = 0;
-            /* Generate interrupt only if OF bit is clear */
-            if (!(env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_OF)) {
-                env->mhpmevent_val[ctr_idx] |= MHPMEVENT_BIT_OF;
-                riscv_cpu_update_mip(env, MIP_LCOFIP, BOOL_TO_MASK(1));
-            }
-        } else {
-            counter->mhpmcounterh_val++;
-        }
-    } else {
-        counter->mhpmcounter_val++;
-    }
-
-    return 0;
-}
-
-static int riscv_pmu_incr_ctr_rv64(RISCVCPU *cpu, uint32_t ctr_idx)
-{
-    CPURISCVState *env = &cpu->env;
-    PMUCTRState *counter = &env->pmu_ctrs[ctr_idx];
-    uint64_t max_val = UINT64_MAX;
-    bool virt_on = env->virt_enabled;
-
-    /* Privilege mode filtering */
-    if ((env->priv == PRV_M &&
-        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_MINH)) ||
-        (env->priv == PRV_S && virt_on &&
-        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_VSINH)) ||
-        (env->priv == PRV_U && virt_on &&
-        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_VUINH)) ||
-        (env->priv == PRV_S && !virt_on &&
-        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_SINH)) ||
-        (env->priv == PRV_U && !virt_on &&
-        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_UINH))) {
-        return 0;
-    }
-
-    /* Handle the overflow scenario */
-    if (counter->mhpmcounter_val == max_val) {
-        counter->mhpmcounter_val = 0;
-        /* Generate interrupt only if OF bit is clear */
-        if (!(env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_OF)) {
-            env->mhpmevent_val[ctr_idx] |= MHPMEVENT_BIT_OF;
-            riscv_cpu_update_mip(env, MIP_LCOFIP, BOOL_TO_MASK(1));
-        }
-    } else {
-        counter->mhpmcounter_val++;
-    }
-    return 0;
-}
-
 /*
  * Information needed to update counters:
  *  new_priv, new_virt: To correctly save starting snapshot for the newly
@@ -275,8 +199,10 @@ void riscv_pmu_update_fixed_ctrs(CPURISCVState *env, target_ulong newpriv,
 int riscv_pmu_incr_ctr(RISCVCPU *cpu, enum riscv_pmu_event_idx event_idx)
 {
     uint32_t ctr_idx;
-    int ret;
     CPURISCVState *env = &cpu->env;
+    uint64_t max_val = UINT64_MAX;
+    bool virt_on = env->virt_enabled;
+    PMUCTRState *counter;
     gpointer value;
 
     if (!cpu->cfg.pmu_mask) {
@@ -293,13 +219,34 @@ int riscv_pmu_incr_ctr(RISCVCPU *cpu, enum riscv_pmu_event_idx event_idx)
         return -1;
     }
 
-    if (riscv_cpu_mxl(env) == MXL_RV32) {
-        ret = riscv_pmu_incr_ctr_rv32(cpu, ctr_idx);
+    /* Privilege mode filtering */
+    if ((env->priv == PRV_M &&
+        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_MINH)) ||
+        (env->priv == PRV_S && virt_on &&
+        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_VSINH)) ||
+        (env->priv == PRV_U && virt_on &&
+        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_VUINH)) ||
+        (env->priv == PRV_S && !virt_on &&
+        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_SINH)) ||
+        (env->priv == PRV_U && !virt_on &&
+        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_UINH))) {
+        return 0;
+    }
+
+    /* Handle the overflow scenario */
+    counter = &env->pmu_ctrs[ctr_idx];
+    if (counter->mhpmcounter_val == max_val) {
+        counter->mhpmcounter_val = 0;
+        /* Generate interrupt only if OF bit is clear */
+        if (!(env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_OF)) {
+            env->mhpmevent_val[ctr_idx] |= MHPMEVENT_BIT_OF;
+            riscv_cpu_update_mip(env, MIP_LCOFIP, BOOL_TO_MASK(1));
+        }
     } else {
-        ret = riscv_pmu_incr_ctr_rv64(cpu, ctr_idx);
+        counter->mhpmcounter_val++;
     }
 
-    return ret;
+    return 0;
 }
 
 bool riscv_pmu_ctr_monitor_instructions(CPURISCVState *env,
@@ -470,8 +417,6 @@ static void pmu_timer_trigger_irq(RISCVCPU *cpu,
     if (riscv_cpu_mxl(env) == MXL_RV32) {
         riscv_pmu_read_ctr(env, (target_ulong *)&curr_ctrh_val, true, ctr_idx);
         curr_ctr_val = curr_ctr_val | (curr_ctrh_val << 32);
-        ctr_val = ctr_val |
-                ((uint64_t)counter->mhpmcounterh_val << 32);
     }
 
     /*
-- 
2.51.0