stimecmp allows the supervisor mode to update stimecmp CSR directly
to program the next timer interrupt. This CSR is part of the Sstc
extension which was ratified recently.
Signed-off-by: Atish Patra <ati...@rivosinc.com>
---
target/riscv/cpu.c | 8 ++++
target/riscv/cpu.h | 5 ++
target/riscv/cpu_bits.h | 4 ++
target/riscv/csr.c | 81 +++++++++++++++++++++++++++++++
target/riscv/machine.c | 1 +
target/riscv/meson.build | 3 +-
target/riscv/time_helper.c | 98 ++++++++++++++++++++++++++++++++++++++
target/riscv/time_helper.h | 30 ++++++++++++
8 files changed, 229 insertions(+), 1 deletion(-)
create mode 100644 target/riscv/time_helper.c
create mode 100644 target/riscv/time_helper.h
diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 19f4e8294042..d58dd2f857a7 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -23,6 +23,7 @@
#include "qemu/log.h"
#include "cpu.h"
#include "internals.h"
+#include "time_helper.h"
#include "exec/exec-all.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
@@ -779,7 +780,12 @@ static void riscv_cpu_init(Object *obj)
#ifndef CONFIG_USER_ONLY
qdev_init_gpio_in(DEVICE(cpu), riscv_cpu_set_irq,
IRQ_LOCAL_MAX + IRQ_LOCAL_GUEST_MAX);
+
+ if (cpu->cfg.ext_sstc) {
+ riscv_timer_init(cpu);
+ }
#endif /* CONFIG_USER_ONLY */
+
}
static Property riscv_cpu_properties[] = {
@@ -806,6 +812,7 @@ static Property riscv_cpu_properties[] = {
DEFINE_PROP_BOOL("mmu", RISCVCPU, cfg.mmu, true),
DEFINE_PROP_BOOL("pmp", RISCVCPU, cfg.pmp, true),
DEFINE_PROP_BOOL("debug", RISCVCPU, cfg.debug, true),
+ DEFINE_PROP_BOOL("sstc", RISCVCPU, cfg.ext_sstc, true),
DEFINE_PROP_STRING("priv_spec", RISCVCPU, cfg.priv_spec),
DEFINE_PROP_STRING("vext_spec", RISCVCPU, cfg.vext_spec),
@@ -965,6 +972,7 @@ static void riscv_isa_string_ext(RISCVCPU *cpu, char
**isa_str, int max_str_len)
ISA_EDATA_ENTRY(zbs, ext_zbs),
ISA_EDATA_ENTRY(zve32f, ext_zve32f),
ISA_EDATA_ENTRY(zve64f, ext_zve64f),
+ ISA_EDATA_ENTRY(sstc, ext_sstc),
ISA_EDATA_ENTRY(svinval, ext_svinval),
ISA_EDATA_ENTRY(svnapot, ext_svnapot),
ISA_EDATA_ENTRY(svpbmt, ext_svpbmt),
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 1119d5201066..9a5e02f217ba 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -276,6 +276,9 @@ struct CPUArchState {
uint64_t mfromhost;
uint64_t mtohost;
+ /* Sstc CSRs */
+ uint64_t stimecmp;
+
/* physical memory protection */
pmp_table_t pmp_state;
target_ulong mseccfg;
@@ -329,6 +332,7 @@ struct CPUArchState {
float_status fp_status;
/* Fields from here on are preserved across CPU reset. */
+ QEMUTimer *stimer; /* Internal timer for S-mode interrupt */
hwaddr kernel_addr;
hwaddr fdt_addr;
@@ -379,6 +383,7 @@ struct RISCVCPUConfig {
bool ext_counters;
bool ext_ifencei;
bool ext_icsr;
+ bool ext_sstc;
bool ext_svinval;
bool ext_svnapot;
bool ext_svpbmt;
diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 4e5b630f5965..29d0e4a1be01 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -215,6 +215,10 @@
#define CSR_STVAL 0x143
#define CSR_SIP 0x144
+/* Sstc supervisor CSRs */
+#define CSR_STIMECMP 0x14D
+#define CSR_STIMECMPH 0x15D
+
/* Supervisor Protection and Translation */
#define CSR_SPTBR 0x180
#define CSR_SATP 0x180
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 245f007e66e1..48d07911ae14 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 "time_helper.h"
#include "qemu/main-loop.h"
#include "exec/exec-all.h"
#include "sysemu/cpu-timers.h"
@@ -537,6 +538,76 @@ static RISCVException read_timeh(CPURISCVState *env, int
csrno,
return RISCV_EXCP_NONE;
}
+static RISCVException sstc(CPURISCVState *env, int csrno)
+{
+ CPUState *cs = env_cpu(env);
+ RISCVCPU *cpu = RISCV_CPU(cs);
+
+ if (!cpu->cfg.ext_sstc || !env->rdtime_fn) {
+ return RISCV_EXCP_ILLEGAL_INST;
+ }
+
+ if (env->priv == PRV_M) {
+ return RISCV_EXCP_NONE;
+ }
+
+ if (env->priv != PRV_S) {
+ return RISCV_EXCP_ILLEGAL_INST;
+ }
+
+ /*
+ * No need of separate function for rv32 as menvcfg stores both menvcfg
+ * menvcfgh for RV32.
+ */
+ if (!(get_field(env->mcounteren, COUNTEREN_TM) &&
+ get_field(env->menvcfg, MENVCFG_STCE))) {
+ return RISCV_EXCP_ILLEGAL_INST;
+ }
+
+ return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_stimecmp(CPURISCVState *env, int csrno,
+ target_ulong *val)
+{
+ *val = env->stimecmp;
+ return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_stimecmph(CPURISCVState *env, int csrno,
+ target_ulong *val)
+{
+ *val = env->stimecmp >> 32;
+ return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_stimecmp(CPURISCVState *env, int csrno,
+ target_ulong val)
+{
+ RISCVCPU *cpu = env_archcpu(env);
+
+ if (riscv_cpu_mxl(env) == MXL_RV32) {
+ env->stimecmp = deposit64(env->stimecmp, 0, 32, (uint64_t)val);
+ } else {
+ env->stimecmp = val;
+ }
+
+ riscv_timer_write_timecmp(cpu, env->stimer, env->stimecmp, 0, MIP_STIP);
+
+ return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_stimecmph(CPURISCVState *env, int csrno,
+ target_ulong val)
+{
+ RISCVCPU *cpu = env_archcpu(env);
+
+ env->stimecmp = deposit64(env->stimecmp, 32, 32, (uint64_t)val);
+ riscv_timer_write_timecmp(cpu, env->stimer, env->stimecmp, 0, MIP_STIP);
+
+ return RISCV_EXCP_NONE;
+}
+
/* Machine constants */
#define M_MODE_INTERRUPTS ((uint64_t)(MIP_MSIP | MIP_MTIP | MIP_MEIP))
@@ -1515,6 +1586,12 @@ static RISCVException rmw_mip64(CPURISCVState *env, int
csrno,
new_val |= env->external_seip * MIP_SEIP;
}
+ if (cpu->cfg.ext_sstc && (env->priv == PRV_M) &&
+ get_field(env->menvcfg, MENVCFG_STCE)) {
+ /* sstc extension forbids STIP & VSTIP to be writeable in mip */
+ mask = mask & ~(MIP_STIP | MIP_VSTIP);
+ }
+
if (mask) {
old_mip = riscv_cpu_update_mip(cpu, mask, (new_val & mask));
} else {
@@ -3341,6 +3418,10 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
[CSR_SCAUSE] = { "scause", smode, read_scause, write_scause },
[CSR_STVAL] = { "stval", smode, read_stval, write_stval },
[CSR_SIP] = { "sip", smode, NULL, NULL, rmw_sip },
+ [CSR_STIMECMP] = { "stimecmp", sstc, read_stimecmp, write_stimecmp,
+ .min_priv_ver = PRIV_VERSION_1_12_0
},
+ [CSR_STIMECMPH] = { "stimecmph", sstc, read_stimecmph, write_stimecmph,
+ .min_priv_ver = PRIV_VERSION_1_12_0
},
/* Supervisor Protection and Translation */
[CSR_SATP] = { "satp", smode, read_satp, write_satp },
diff --git a/target/riscv/machine.c b/target/riscv/machine.c
index 7d85de0b1d49..ee02bfc18916 100644
--- a/target/riscv/machine.c
+++ b/target/riscv/machine.c
@@ -334,6 +334,7 @@ const VMStateDescription vmstate_riscv_cpu = {
VMSTATE_UINTTL(env.mscratch, RISCVCPU),
VMSTATE_UINT64(env.mfromhost, RISCVCPU),
VMSTATE_UINT64(env.mtohost, RISCVCPU),
+ VMSTATE_UINT64(env.stimecmp, RISCVCPU),
VMSTATE_END_OF_LIST()
},
diff --git a/target/riscv/meson.build b/target/riscv/meson.build
index 2c20f3dd8e9c..1243d019148e 100644
--- a/target/riscv/meson.build
+++ b/target/riscv/meson.build
@@ -29,7 +29,8 @@ riscv_softmmu_ss.add(files(
'pmp.c',
'debug.c',
'monitor.c',
- 'machine.c'
+ 'machine.c',
+ 'time_helper.c'
))
target_arch += {'riscv': riscv_ss}
diff --git a/target/riscv/time_helper.c b/target/riscv/time_helper.c
new file mode 100644
index 000000000000..f3fb5eac7b7b
--- /dev/null
+++ b/target/riscv/time_helper.c
@@ -0,0 +1,98 @@
+/*
+ * RISC-V timer helper implementation.
+ *
+ * Copyright (c) 2022 Rivos Inc.
+ *
+ * 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_bits.h"
+#include "time_helper.h"
+#include "hw/intc/riscv_aclint.h"
+
+static void riscv_stimer_cb(void *opaque)
+{
+ RISCVCPU *cpu = opaque;
+ riscv_cpu_update_mip(cpu, MIP_STIP, BOOL_TO_MASK(1));
+}
+
+/*
+ * Called when timecmp is written to update the QEMU timer or immediately
+ * trigger timer interrupt if mtimecmp <= current timer value.
+ */
+void riscv_timer_write_timecmp(RISCVCPU *cpu, QEMUTimer *timer,
+ uint64_t timecmp, uint64_t delta,
+ uint32_t timer_irq)
+{
+ uint64_t diff, ns_diff, next;
+ CPURISCVState *env = &cpu->env;
+ RISCVAclintMTimerState *mtimer = env->rdtime_fn_arg;
+ uint32_t timebase_freq = mtimer->timebase_freq;
+ uint64_t rtc_r = env->rdtime_fn(env->rdtime_fn_arg) + delta;
+
+ if (timecmp <= rtc_r) {
+ /*
+ * If we're setting an stimecmp value in the "past",
+ * immediately raise the timer interrupt
+ */
+ riscv_cpu_update_mip(cpu, timer_irq, BOOL_TO_MASK(1));
+ return;
+ }
+
+ /* Clear the [V]STIP bit in mip */
+ riscv_cpu_update_mip(cpu, timer_irq, BOOL_TO_MASK(0));
+
+ /* otherwise, set up the future timer interrupt */
+ diff = timecmp - rtc_r;
+ /* back to ns (note args switched in muldiv64) */
+ ns_diff = muldiv64(diff, NANOSECONDS_PER_SECOND, timebase_freq);
+
+ /*
+ * check if ns_diff overflowed and check if the addition would potentially
+ * overflow
+ */
+ if ((NANOSECONDS_PER_SECOND > timebase_freq && ns_diff < diff) ||
+ ns_diff > INT64_MAX) {
+ next = INT64_MAX;
+ } else {
+ /*
+ * as it is very unlikely qemu_clock_get_ns will return a value
+ * greater than INT64_MAX, no additional check is needed for an
+ * unsigned integer overflow.
+ */
+ next = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + ns_diff;
+ /*
+ * if ns_diff is INT64_MAX next may still be outside the range
+ * of a signed integer.
+ */
+ next = MIN(next, INT64_MAX);
+ }
+
+ timer_mod(timer, next);
+}
+
+void riscv_timer_init(RISCVCPU *cpu)
+{
+ CPURISCVState *env;
+
+ if (!cpu) {
+ return;
+ }
+
+ env = &cpu->env;
+ env->stimer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &riscv_stimer_cb, cpu);
+ env->stimecmp = 0;
+
+}
diff --git a/target/riscv/time_helper.h b/target/riscv/time_helper.h
new file mode 100644
index 000000000000..7b3cdcc35020
--- /dev/null
+++ b/target/riscv/time_helper.h
@@ -0,0 +1,30 @@
+/*
+ * RISC-V timer header file.
+ *
+ * Copyright (c) 2022 Rivos Inc.
+ *
+ * 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/>.
+ */
+
+#ifndef RISCV_TIME_HELPER_H
+#define RISCV_TIME_HELPER_H
+
+#include "cpu.h"
+#include "qemu/timer.h"
+
+void riscv_timer_write_timecmp(RISCVCPU *cpu, QEMUTimer *timer,
+ uint64_t timecmp, uint64_t delta,
+ uint32_t timer_irq);
+void riscv_timer_init(RISCVCPU *cpu);
+
+#endif
--
2.25.1
