[PATCH v9 07/12] target/riscv: Support mcycle/minstret write operation
From: Atish Patra
Date: Mon May 23 2022 - 19:52:09 EST
From: Atish Patra <atish.patra@xxxxxxx>
mcycle/minstret are actually WARL registers and can be written with any
given value. With SBI PMU extension, it will be used to store a initial
value provided from supervisor OS. The Qemu also need prohibit the counter
increment if mcountinhibit is set.
Support mcycle/minstret through generic counter infrastructure.
Reviewed-by: Alistair Francis <alistair.francis@xxxxxxx>
Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx>
---
target/riscv/cpu.h | 23 ++++--
target/riscv/csr.c | 155 ++++++++++++++++++++++++++++-----------
target/riscv/machine.c | 25 ++++++-
target/riscv/meson.build | 3 +-
target/riscv/pmu.c | 32 ++++++++
target/riscv/pmu.h | 28 +++++++
6 files changed, 213 insertions(+), 53 deletions(-)
create mode 100644 target/riscv/pmu.c
create mode 100644 target/riscv/pmu.h
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 32cdd9070be5..f60072e0fd3d 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -111,7 +111,7 @@ typedef struct CPUArchState CPURISCVState;
#endif
#define RV_VLEN_MAX 1024
-#define RV_MAX_MHPMEVENTS 29
+#define RV_MAX_MHPMEVENTS 32
#define RV_MAX_MHPMCOUNTERS 32
FIELD(VTYPE, VLMUL, 0, 3)
@@ -121,6 +121,18 @@ FIELD(VTYPE, VMA, 7, 1)
FIELD(VTYPE, VEDIV, 8, 2)
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;
+ /* Snapshot values of counter */
+ target_ulong mhpmcounter_prev;
+ /* Snapshort value of a counter in RV32 */
+ target_ulong mhpmcounterh_prev;
+ bool started;
+} PMUCTRState;
+
struct CPUArchState {
target_ulong gpr[32];
target_ulong gprh[32]; /* 64 top bits of the 128-bit registers */
@@ -273,13 +285,10 @@ struct CPUArchState {
target_ulong mcountinhibit;
- /* PMU counter configured values */
- target_ulong mhpmcounter_val[RV_MAX_MHPMCOUNTERS];
-
- /* for RV32 */
- target_ulong mhpmcounterh_val[RV_MAX_MHPMCOUNTERS];
+ /* PMU counter state */
+ PMUCTRState pmu_ctrs[RV_MAX_MHPMCOUNTERS];
- /* PMU event selector configured values */
+ /* PMU event selector configured values. First three are unused*/
target_ulong mhpmevent_val[RV_MAX_MHPMEVENTS];
target_ulong sscratch;
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 605591072784..d109f329ce73 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -21,6 +21,7 @@
#include "qemu/log.h"
#include "qemu/timer.h"
#include "cpu.h"
+#include "pmu.h"
#include "qemu/main-loop.h"
#include "exec/exec-all.h"
#include "sysemu/cpu-timers.h"
@@ -597,34 +598,28 @@ static int write_vcsr(CPURISCVState *env, int csrno, target_ulong val)
}
/* User Timers and Counters */
-static RISCVException read_instret(CPURISCVState *env, int csrno,
- target_ulong *val)
+static target_ulong get_ticks(bool shift)
{
+ int64_t val;
+ target_ulong result;
+
#if !defined(CONFIG_USER_ONLY)
if (icount_enabled()) {
- *val = icount_get();
+ val = icount_get();
} else {
- *val = cpu_get_host_ticks();
+ val = cpu_get_host_ticks();
}
#else
- *val = cpu_get_host_ticks();
+ val = cpu_get_host_ticks();
#endif
- return RISCV_EXCP_NONE;
-}
-static RISCVException read_instreth(CPURISCVState *env, int csrno,
- target_ulong *val)
-{
-#if !defined(CONFIG_USER_ONLY)
- if (icount_enabled()) {
- *val = icount_get() >> 32;
+ if (shift) {
+ result = val >> 32;
} else {
- *val = cpu_get_host_ticks() >> 32;
+ result = val;
}
-#else
- *val = cpu_get_host_ticks() >> 32;
-#endif
- return RISCV_EXCP_NONE;
+
+ return result;
}
#if defined(CONFIG_USER_ONLY)
@@ -642,11 +637,23 @@ static RISCVException read_timeh(CPURISCVState *env, int csrno,
return RISCV_EXCP_NONE;
}
+static int read_hpmcounter(CPURISCVState *env, int csrno, target_ulong *val)
+{
+ *val = get_ticks(false);
+ return RISCV_EXCP_NONE;
+}
+
+static int read_hpmcounterh(CPURISCVState *env, int csrno, target_ulong *val)
+{
+ *val = get_ticks(true);
+ return RISCV_EXCP_NONE;
+}
+
#else /* CONFIG_USER_ONLY */
static int read_mhpmevent(CPURISCVState *env, int csrno, target_ulong *val)
{
- int evt_index = csrno - CSR_MHPMEVENT3;
+ int evt_index = csrno - CSR_MCOUNTINHIBIT;
*val = env->mhpmevent_val[evt_index];
@@ -655,7 +662,7 @@ static int read_mhpmevent(CPURISCVState *env, int csrno, target_ulong *val)
static int write_mhpmevent(CPURISCVState *env, int csrno, target_ulong val)
{
- int evt_index = csrno - CSR_MHPMEVENT3;
+ int evt_index = csrno - CSR_MCOUNTINHIBIT;
env->mhpmevent_val[evt_index] = val;
@@ -664,55 +671,105 @@ static int write_mhpmevent(CPURISCVState *env, int csrno, target_ulong val)
static int write_mhpmcounter(CPURISCVState *env, int csrno, target_ulong val)
{
- int ctr_index = csrno - CSR_MHPMCOUNTER3 + 3;
+ int ctr_idx = csrno - CSR_MCYCLE;
+ PMUCTRState *counter = &env->pmu_ctrs[ctr_idx];
- env->mhpmcounter_val[ctr_index] = val;
+ counter->mhpmcounter_val = val;
+ if (riscv_pmu_ctr_monitor_cycles(env, ctr_idx) ||
+ riscv_pmu_ctr_monitor_instructions(env, ctr_idx)) {
+ counter->mhpmcounter_prev = get_ticks(false);
+ } else {
+ /* Other counters can keep incrementing from the given value */
+ counter->mhpmcounter_prev = val;
+ }
return RISCV_EXCP_NONE;
}
static int write_mhpmcounterh(CPURISCVState *env, int csrno, target_ulong val)
{
- int ctr_index = csrno - CSR_MHPMCOUNTER3H + 3;
+ int ctr_idx = csrno - CSR_MCYCLEH;
+ PMUCTRState *counter = &env->pmu_ctrs[ctr_idx];
- env->mhpmcounterh_val[ctr_index] = val;
+ counter->mhpmcounterh_val = val;
+ if (riscv_pmu_ctr_monitor_cycles(env, ctr_idx) ||
+ riscv_pmu_ctr_monitor_instructions(env, ctr_idx)) {
+ counter->mhpmcounterh_prev = get_ticks(true);
+ } else {
+ counter->mhpmcounterh_prev = val;
+ }
+
+ return RISCV_EXCP_NONE;
+}
+
+static RISCVException riscv_pmu_read_ctr(CPURISCVState *env, target_ulong *val,
+ 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;
+
+ if (get_field(env->mcountinhibit, BIT(ctr_idx))) {
+ /**
+ * Counter should not increment if inhibit bit is set. We can't really
+ * stop the icount counting. Just return the counter value written by
+ * the supervisor to indicate that counter was not incremented.
+ */
+ if (!counter.started) {
+ *val = ctr_val;
+ return RISCV_EXCP_NONE;
+ } else {
+ /* Mark that the counter has been stopped */
+ counter.started = false;
+ }
+ }
+
+ /**
+ * The kernel computes the perf delta by subtracting the current value from
+ * the value it initialized previously (ctr_val).
+ */
+ if (riscv_pmu_ctr_monitor_cycles(env, ctr_idx) ||
+ riscv_pmu_ctr_monitor_instructions(env, ctr_idx)) {
+ *val = get_ticks(upper_half) - ctr_prev + ctr_val;
+ } else {
+ *val = ctr_val;
+ }
return RISCV_EXCP_NONE;
}
static int read_hpmcounter(CPURISCVState *env, int csrno, target_ulong *val)
{
- int ctr_index;
+ uint16_t ctr_index;
if (csrno >= CSR_MCYCLE && csrno <= CSR_MHPMCOUNTER31) {
- ctr_index = csrno - CSR_MHPMCOUNTER3 + 3;
+ ctr_index = csrno - CSR_MCYCLE;
} else if (csrno >= CSR_CYCLE && csrno <= CSR_HPMCOUNTER31) {
- ctr_index = csrno - CSR_HPMCOUNTER3 + 3;
+ ctr_index = csrno - CSR_CYCLE;
} else {
return RISCV_EXCP_ILLEGAL_INST;
}
- *val = env->mhpmcounter_val[ctr_index];
- return RISCV_EXCP_NONE;
+ return riscv_pmu_read_ctr(env, val, false, ctr_index);
}
static int read_hpmcounterh(CPURISCVState *env, int csrno, target_ulong *val)
{
- int ctr_index;
+ uint16_t ctr_index;
if (csrno >= CSR_MCYCLEH && csrno <= CSR_MHPMCOUNTER31H) {
- ctr_index = csrno - CSR_MHPMCOUNTER3H + 3;
+ ctr_index = csrno - CSR_MCYCLEH;
} else if (csrno >= CSR_CYCLEH && csrno <= CSR_HPMCOUNTER31H) {
- ctr_index = csrno - CSR_HPMCOUNTER3H + 3;
+ ctr_index = csrno - CSR_CYCLEH;
} else {
return RISCV_EXCP_ILLEGAL_INST;
}
- *val = env->mhpmcounterh_val[ctr_index];
- return RISCV_EXCP_NONE;
+ return riscv_pmu_read_ctr(env, val, true, ctr_index);
}
-
static RISCVException read_time(CPURISCVState *env, int csrno,
target_ulong *val)
{
@@ -1567,11 +1624,23 @@ static RISCVException read_mcountinhibit(CPURISCVState *env, int csrno,
static RISCVException write_mcountinhibit(CPURISCVState *env, int csrno,
target_ulong val)
{
+ int cidx;
+ PMUCTRState *counter;
+
if (env->priv_ver < PRIV_VERSION_1_11_0) {
return RISCV_EXCP_ILLEGAL_INST;
}
env->mcountinhibit = val;
+
+ /* Check if any other counter is also monitoring cycles/instructions */
+ for (cidx = 0; cidx < RV_MAX_MHPMCOUNTERS; cidx++) {
+ if (!get_field(env->mcountinhibit, BIT(cidx))) {
+ counter = &env->pmu_ctrs[cidx];
+ counter->started = true;
+ }
+ }
+
return RISCV_EXCP_NONE;
}
@@ -3529,10 +3598,10 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
[CSR_VLENB] = { "vlenb", vs, read_vlenb,
.min_priv_ver = PRIV_VERSION_1_12_0 },
/* User Timers and Counters */
- [CSR_CYCLE] = { "cycle", ctr, read_instret },
- [CSR_INSTRET] = { "instret", ctr, read_instret },
- [CSR_CYCLEH] = { "cycleh", ctr32, read_instreth },
- [CSR_INSTRETH] = { "instreth", ctr32, read_instreth },
+ [CSR_CYCLE] = { "cycle", ctr, read_hpmcounter },
+ [CSR_INSTRET] = { "instret", ctr, read_hpmcounter },
+ [CSR_CYCLEH] = { "cycleh", ctr32, read_hpmcounterh },
+ [CSR_INSTRETH] = { "instreth", ctr32, read_hpmcounterh },
/*
* In privileged mode, the monitor will have to emulate TIME CSRs only if
@@ -3546,10 +3615,10 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
#if !defined(CONFIG_USER_ONLY)
/* Machine Timers and Counters */
- [CSR_MCYCLE] = { "mcycle", any, read_instret },
- [CSR_MINSTRET] = { "minstret", any, read_instret },
- [CSR_MCYCLEH] = { "mcycleh", any32, read_instreth },
- [CSR_MINSTRETH] = { "minstreth", any32, read_instreth },
+ [CSR_MCYCLE] = { "mcycle", any, read_hpmcounter, write_mhpmcounter},
+ [CSR_MINSTRET] = { "minstret", any, read_hpmcounter, write_mhpmcounter},
+ [CSR_MCYCLEH] = { "mcycleh", any32, read_hpmcounterh, write_mhpmcounterh},
+ [CSR_MINSTRETH] = { "minstreth", any32, read_hpmcounterh, write_mhpmcounterh},
/* Machine Information Registers */
[CSR_MVENDORID] = { "mvendorid", any, read_mvendorid },
diff --git a/target/riscv/machine.c b/target/riscv/machine.c
index 99193c85bb97..dc182ca81119 100644
--- a/target/riscv/machine.c
+++ b/target/riscv/machine.c
@@ -279,7 +279,28 @@ static const VMStateDescription vmstate_envcfg = {
VMSTATE_UINT64(env.menvcfg, RISCVCPU),
VMSTATE_UINTTL(env.senvcfg, RISCVCPU),
VMSTATE_UINT64(env.henvcfg, RISCVCPU),
+ VMSTATE_END_OF_LIST()
+ }
+};
+
+static bool pmu_needed(void *opaque)
+{
+ RISCVCPU *cpu = opaque;
+ return cpu->cfg.pmu_num;
+}
+
+static const VMStateDescription vmstate_pmu_ctr_state = {
+ .name = "cpu/pmu",
+ .version_id = 1,
+ .minimum_version_id = 1,
+ .needed = pmu_needed,
+ .fields = (VMStateField[]) {
+ VMSTATE_UINTTL(mhpmcounter_val, PMUCTRState),
+ VMSTATE_UINTTL(mhpmcounterh_val, PMUCTRState),
+ VMSTATE_UINTTL(mhpmcounter_prev, PMUCTRState),
+ VMSTATE_UINTTL(mhpmcounterh_prev, PMUCTRState),
+ VMSTATE_BOOL(started, PMUCTRState),
VMSTATE_END_OF_LIST()
}
};
@@ -331,8 +352,8 @@ const VMStateDescription vmstate_riscv_cpu = {
VMSTATE_UINTTL(env.scounteren, RISCVCPU),
VMSTATE_UINTTL(env.mcounteren, RISCVCPU),
VMSTATE_UINTTL(env.mcountinhibit, RISCVCPU),
- VMSTATE_UINTTL_ARRAY(env.mhpmcounter_val, RISCVCPU, RV_MAX_MHPMCOUNTERS),
- VMSTATE_UINTTL_ARRAY(env.mhpmcounterh_val, RISCVCPU, RV_MAX_MHPMCOUNTERS),
+ VMSTATE_STRUCT_ARRAY(env.pmu_ctrs, RISCVCPU, RV_MAX_MHPMCOUNTERS, 0,
+ vmstate_pmu_ctr_state, PMUCTRState),
VMSTATE_UINTTL_ARRAY(env.mhpmevent_val, RISCVCPU, RV_MAX_MHPMEVENTS),
VMSTATE_UINTTL(env.sscratch, RISCVCPU),
VMSTATE_UINTTL(env.mscratch, RISCVCPU),
diff --git a/target/riscv/meson.build b/target/riscv/meson.build
index 096249f3a30f..2c1975e72c4e 100644
--- a/target/riscv/meson.build
+++ b/target/riscv/meson.build
@@ -30,7 +30,8 @@ riscv_softmmu_ss.add(files(
'pmp.c',
'debug.c',
'monitor.c',
- 'machine.c'
+ 'machine.c',
+ 'pmu.c'
))
target_arch += {'riscv': riscv_ss}
diff --git a/target/riscv/pmu.c b/target/riscv/pmu.c
new file mode 100644
index 000000000000..000fe8da45ef
--- /dev/null
+++ b/target/riscv/pmu.c
@@ -0,0 +1,32 @@
+/*
+ * RISC-V PMU file.
+ *
+ * Copyright (c) 2021 Western Digital Corporation or its affiliates.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "pmu.h"
+
+bool riscv_pmu_ctr_monitor_instructions(CPURISCVState *env,
+ uint32_t target_ctr)
+{
+ return (target_ctr == 0) ? true : false;
+}
+
+bool riscv_pmu_ctr_monitor_cycles(CPURISCVState *env, uint32_t target_ctr)
+{
+ return (target_ctr == 2) ? true : false;
+}
diff --git a/target/riscv/pmu.h b/target/riscv/pmu.h
new file mode 100644
index 000000000000..58a5bc3a4089
--- /dev/null
+++ b/target/riscv/pmu.h
@@ -0,0 +1,28 @@
+/*
+ * RISC-V PMU header file.
+ *
+ * Copyright (c) 2021 Western Digital Corporation or its affiliates.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "cpu.h"
+#include "qemu/main-loop.h"
+#include "exec/exec-all.h"
+
+bool riscv_pmu_ctr_monitor_instructions(CPURISCVState *env,
+ uint32_t target_ctr);
+bool riscv_pmu_ctr_monitor_cycles(CPURISCVState *env,
+ uint32_t target_ctr);
--
2.25.1