On Sun, Jan 9, 2022 at 11:51 PM Bin Meng <bmeng...@gmail.com> wrote:
>
> On Fri, Jan 7, 2022 at 10:14 AM Atish Patra <ati...@rivosinc.com> wrote:
> >
> > From: Atish Patra <atish.pa...@wdc.com>
> >
> > 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.
> >
> > Signed-off-by: Atish Patra <atish.pa...@wdc.com>
> > Signed-off-by: Atish Patra <ati...@rivosinc.com>
> > ---
> > target/riscv/cpu.h | 24 +++++--
> > target/riscv/csr.c | 144 ++++++++++++++++++++++++++-------------
> > target/riscv/machine.c | 26 ++++++-
> > target/riscv/meson.build | 1 +
> > target/riscv/pmu.c | 32 +++++++++
> > target/riscv/pmu.h | 28 ++++++++
> > 6 files changed, 200 insertions(+), 55 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 39edc948d703..5fe9c51b38c7 100644
> > --- a/target/riscv/cpu.h
> > +++ b/target/riscv/cpu.h
> > @@ -101,7 +101,7 @@ typedef struct CPURISCVState 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)
> > @@ -112,6 +112,19 @@ FIELD(VTYPE, VEDIV, 8, 2)
> > FIELD(VTYPE, RESERVED, 10, sizeof(target_ulong) * 8 - 11)
> > FIELD(VTYPE, VILL, sizeof(target_ulong) * 8 - 1, 1)
> >
> > +typedef struct PMUCTRState PMUCTRState;
>
> This 'typedef' can be merged into the definition below
>
Sure.
>
> > +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;
> > +};
> > +
> > struct CPURISCVState {
> > target_ulong gpr[32];
> > uint64_t fpr[32]; /* assume both F and D extensions */
> > @@ -226,13 +239,10 @@ struct CPURISCVState {
> >
> > 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 58a9550bd898..d4449ada557c 100644
> > --- a/target/riscv/csr.c
> > +++ b/target/riscv/csr.c
> > @@ -20,6 +20,7 @@
> > #include "qemu/osdep.h"
> > #include "qemu/log.h"
> > #include "cpu.h"
> > +#include "pmu.h"
> > #include "qemu/main-loop.h"
> > #include "exec/exec-all.h"
> >
> > @@ -461,41 +462,33 @@ 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_icount_ticks(bool brv32)
>
> I would use 'rv32' instead of 'brv32'
>
ok.
> > {
> > + 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 (brv32) {
> > + 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;
> > }
> >
> > 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];
> >
> > @@ -504,7 +497,7 @@ 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;
> >
> > @@ -513,52 +506,99 @@ 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_icount_ticks(false);
> > + } else {
> > + /* Other counters can keep incrementing from the given value */
> > + counter->mhpmcounter_prev = val;
> > + }
> >
> > - return RISCV_EXCP_NONE;
> > + return RISCV_EXCP_NONE;
>
> The indentation is wrong, which should be 4 spaces. The same issue
> exists in above if .. else .. block.
>
Oops. will fix it.
> > }
> >
> > 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];
> > +
> > + 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_icount_ticks(false);
>
> Should be get_icount_ticks(true)
>
Yup. Thanks for catching that.
> > + } else {
> > + counter->mhpmcounterh_prev = val;
> > + }
> > +
> > + return RISCV_EXCP_NONE;
> > +}
> > +
> > +static RISCVException riscv_pmu_read_ctr(CPURISCVState *env, target_ulong
> > *val,
> > + bool is_uh, uint32_t ctr_idx)
>
> nits: %s/is_uh/upper_half to make it more intuitive?
>
ok. will change it.
> > +{
> > + PMUCTRState counter = env->pmu_ctrs[ctr_idx];
> > + target_ulong ctr_prev = is_uh ? counter.mhpmcounterh_prev :
> > + counter.mhpmcounter_prev;
> > + target_ulong ctr_val = is_uh ? counter.mhpmcounterh_val :
> > + counter.mhpmcounter_val;
> >
> > - env->mhpmcounterh_val[ctr_index] = 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 previous value to
> > indicate
> > + * that counter was not incremented.
> > + */
> > + if (!counter.started) {
> > + *val = ctr_val;
>
> I think this should be *val = ctl_prev to match your comments?
>
ctr_val - has the value written from the supervisor previously
ctr_prev - has the previous value read from the counter
As the kernel should see the exact same value it has written
previously to the counter
it should ctr_val.
The comment probably doesn't explain it correctly. I will update it.
> > + return RISCV_EXCP_NONE;
> > + } else {
> > + /* Mark that the counter has been stopped */
> > + counter.started = false;
> > + }
> > + }
> > + if (riscv_pmu_ctr_monitor_cycles(env, ctr_idx) ||
> > + riscv_pmu_ctr_monitor_instructions(env, ctr_idx)) {
> > + *val = get_icount_ticks(is_uh);
> > + } else {
> > + *val = ctr_val;
>
> *val = ctr_prev?
>
Yeah if we want to retain the below line.
However, I think we can simplify by just moving the below line for if condition
which is applicable only for cycles & instructions.
> > + }
> > +
> > + /* No need to handle the overflow here */
> > + *val = *val - ctr_prev + ctr_val;
>
> I am not sure I understand the logic here.
>
> For cycle/instret counters, this logic becomes: new get_icount_ticks()
> - get_icount_ticks() last time when counter was written + the counter
> value last time when counter was written. This does not make sense.
>
The kernel computes the perf delta by subtracting the current value from
the value it initialized previously.
That's why we need to add the delta value (current get_icount_ticks()
- previous get_icount_ticks())
to the counter value it was written last time.
Let me know if I should add a comment about this to avoid further confusion.
> >
> > return RISCV_EXCP_NONE;
> > }
> >
> > static int read_hpmcounter(CPURISCVState *env, int csrno, target_ulong
> > *val)
> > {
> > - int ctr_index;
> > + uint16_t ctr_index;
> >
> > if (env->priv == PRV_M) {
> > - ctr_index = csrno - CSR_MHPMCOUNTER3 + 3;
> > + ctr_index = csrno - CSR_MCYCLE;
> > } else {
> > - ctr_index = csrno - CSR_HPMCOUNTER3 + 3;
> > + ctr_index = csrno - CSR_CYCLE;
> > }
> > - *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 (env->priv == PRV_M) {
> > - ctr_index = csrno - CSR_MHPMCOUNTER3H + 3;
> > + ctr_index = csrno - CSR_MCYCLEH;
> > } else {
> > - ctr_index = csrno - CSR_HPMCOUNTER3H + 3;
> > + ctr_index = csrno - CSR_CYCLEH;
> > }
> >
> > - *val = env->mhpmcounterh_val[ctr_index];
> > -
> > - return RISCV_EXCP_NONE;
> > + return riscv_pmu_read_ctr(env, val, true, ctr_index);
> > }
> >
> > -
> > #if defined(CONFIG_USER_ONLY)
> > static RISCVException read_time(CPURISCVState *env, int csrno,
> > target_ulong *val)
> > @@ -925,11 +965,23 @@ 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;
> > }
> >
> > @@ -2035,10 +2087,10 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
> > [CSR_VTYPE] = { "vtype", vs, read_vtype },
> > [CSR_VLENB] = { "vlenb", vs, read_vlenb },
> > /* 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
> > @@ -2049,10 +2101,10 @@ 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_zero },
> > diff --git a/target/riscv/machine.c b/target/riscv/machine.c
> > index d10a3d7472cb..829b9f2d1f46 100644
> > --- a/target/riscv/machine.c
> > +++ b/target/riscv/machine.c
> > @@ -164,6 +164,28 @@ static const VMStateDescription vmstate_pointermasking
> > = {
> > }
> > };
> >
> > +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()
> > + }
> > +};
> > +
> > const VMStateDescription vmstate_riscv_cpu = {
> > .name = "cpu",
> > .version_id = 3,
> > @@ -206,8 +228,8 @@ 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 d5e0bc93ea9c..992122c4d6f5 100644
> > --- a/target/riscv/meson.build
> > +++ b/target/riscv/meson.build
> > @@ -24,6 +24,7 @@ riscv_softmmu_ss = ss.source_set()
> > riscv_softmmu_ss.add(files(
> > 'arch_dump.c',
> > 'pmp.c',
> > + 'pmu.c',
> > 'monitor.c',
> > 'machine.c'
> > ))
> > 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;
> > +}
>
> Maybe it makes sense to move all PMU CSRs read/write routine into this
> new pmu.c file? It looks odd to just add 2 simple functions here.
>
> > 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);
> > --
>
> Regards,
> Bin
>
--
Regards,
Atish
