On Tue, May 10, 2022 at 3:03 AM Atish Patra <ati...@rivosinc.com> wrote:
>
> vstimecmp CSR allows the guest OS or to program the next guest timer
> interrupt directly. Thus, hypervisor no longer need to inject the
> timer interrupt to the guest if vstimecmp is used. This was ratified
> as a part of the Sstc extension.
>
> Signed-off-by: Atish Patra <ati...@rivosinc.com>
> ---
> target/riscv/cpu.h | 5 ++
> target/riscv/cpu_bits.h | 4 ++
> target/riscv/cpu_helper.c | 11 +++-
> target/riscv/csr.c | 112 ++++++++++++++++++++++++++++++++++++-
> target/riscv/machine.c | 1 +
> target/riscv/time_helper.c | 16 ++++++
> 6 files changed, 144 insertions(+), 5 deletions(-)
>
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 9a01e6d0f587..798874d6189d 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -280,6 +280,9 @@ struct CPUArchState {
> uint64_t stimecmp;
> /* For RV32 only */
> uint8_t stimecmp_wr_done;
Add new line here.
> + uint64_t vstimecmp;
> + /* For RV32 only */
> + uint8_t vstimecmp_wr_done;
>
> /* physical memory protection */
> pmp_table_t pmp_state;
> @@ -335,6 +338,8 @@ struct CPUArchState {
>
> /* Fields from here on are preserved across CPU reset. */
> QEMUTimer *stimer; /* Internal timer for S-mode interrupt */
> + QEMUTimer *vstimer; /* Internal timer for VS-mode interrupt */
> + bool vstime_irq;
>
> hwaddr kernel_addr;
> hwaddr fdt_addr;
> diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
> index 29d0e4a1be01..5c9f512872e1 100644
> --- a/target/riscv/cpu_bits.h
> +++ b/target/riscv/cpu_bits.h
> @@ -272,6 +272,10 @@
> #define CSR_VSIP 0x244
> #define CSR_VSATP 0x280
>
> +/* Sstc virtual CSRs */
> +#define CSR_VSTIMECMP 0x24D
> +#define CSR_VSTIMECMPH 0x25D
> +
> #define CSR_MTINST 0x34a
> #define CSR_MTVAL2 0x34b
>
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index e1aa4f2097c1..2715021c022e 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -344,8 +344,9 @@ static uint64_t riscv_cpu_all_pending(CPURISCVState *env)
> {
> uint32_t gein = get_field(env->hstatus, HSTATUS_VGEIN);
> uint64_t vsgein = (env->hgeip & (1ULL << gein)) ? MIP_VSEIP : 0;
> + uint64_t vstip = (env->vstime_irq) ? MIP_VSTIP : 0;
>
> - return (env->mip | vsgein) & env->mie;
> + return (env->mip | vsgein | vstip) & env->mie;
> }
>
> int riscv_cpu_mirq_pending(CPURISCVState *env)
> @@ -604,7 +605,7 @@ uint64_t riscv_cpu_update_mip(RISCVCPU *cpu, uint64_t
> mask, uint64_t value)
> {
> CPURISCVState *env = &cpu->env;
> CPUState *cs = CPU(cpu);
> - uint64_t gein, vsgein = 0, old = env->mip;
> + uint64_t gein, vsgein = 0, vstip = 0, old = env->mip;
> bool locked = false;
>
> if (riscv_cpu_virt_enabled(env)) {
> @@ -612,6 +613,10 @@ uint64_t riscv_cpu_update_mip(RISCVCPU *cpu, uint64_t
> mask, uint64_t value)
> vsgein = (env->hgeip & (1ULL << gein)) ? MIP_VSEIP : 0;
> }
>
> + /* No need to update mip for VSTIP */
> + mask = ((mask == MIP_VSTIP) && env->vstime_irq) ? 0 : mask;
> + vstip = env->vstime_irq ? MIP_VSTIP : 0;
> +
> if (!qemu_mutex_iothread_locked()) {
> locked = true;
> qemu_mutex_lock_iothread();
> @@ -619,7 +624,7 @@ uint64_t riscv_cpu_update_mip(RISCVCPU *cpu, uint64_t
> mask, uint64_t value)
>
> env->mip = (env->mip & ~mask) | (value & mask);
>
> - if (env->mip | vsgein) {
> + if (env->mip | vsgein | vstip) {
> cpu_interrupt(cs, CPU_INTERRUPT_HARD);
> } else {
> cpu_reset_interrupt(cs, CPU_INTERRUPT_HARD);
> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> index 8952d1308008..35eb2c4d84eb 100644
> --- a/target/riscv/csr.c
> +++ b/target/riscv/csr.c
> @@ -567,17 +567,110 @@ static RISCVException sstc(CPURISCVState *env, int
> csrno)
> return RISCV_EXCP_NONE;
> }
>
> +static RISCVException sstc_hmode(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 (!(get_field(env->mcounteren, COUNTEREN_TM) &
> + get_field(env->menvcfg, MENVCFG_STCE))) {
> + return RISCV_EXCP_ILLEGAL_INST;
> + }
> +
> + if (!(get_field(env->hcounteren, COUNTEREN_TM) &
> + get_field(env->henvcfg, HENVCFG_STCE))) {
> + return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
> + }
> +
> + return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException read_vstimecmp(CPURISCVState *env, int csrno,
> + target_ulong *val)
> +{
> + *val = env->vstimecmp;
> +
> + return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException read_vstimecmph(CPURISCVState *env, int csrno,
> + target_ulong *val)
> +{
> + *val = env->vstimecmp >> 32;
> +
> + return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_vstimecmp(CPURISCVState *env, int csrno,
> + target_ulong val)
> +{
> + RISCVCPU *cpu = env_archcpu(env);
> +
> + if (riscv_cpu_mxl(env) == MXL_RV32) {
> + env->vstimecmp = deposit64(env->vstimecmp, 0, 32, (uint64_t)val);
> + env->vstimecmp_wr_done |= 0x01;
> + if (env->vstimecmp_wr_done != 0x03) {
> + return RISCV_EXCP_NONE;
> + } else {
> + env->vstimecmp_wr_done = 0;
> + }
> + } else {
> + env->vstimecmp = val;
> + }
> +
> + riscv_timer_write_timecmp(cpu, env->vstimer, env->vstimecmp,
> + env->htimedelta, MIP_VSTIP);
> +
> + return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_vstimecmph(CPURISCVState *env, int csrno,
> + target_ulong val)
> +{
> + RISCVCPU *cpu = env_archcpu(env);
> +
> + env->vstimecmp = deposit64(env->vstimecmp, 32, 32, (uint64_t)val);
> + env->vstimecmp_wr_done |= 0x02;
> + if (env->vstimecmp_wr_done != 0x03) {
> + return RISCV_EXCP_NONE;
> + }
> +
> + env->vstimecmp_wr_done = 0;
> + riscv_timer_write_timecmp(cpu, env->vstimer, env->vstimecmp,
> + env->htimedelta, MIP_VSTIP);
> +
> + return RISCV_EXCP_NONE;
> +}
> +
> static RISCVException read_stimecmp(CPURISCVState *env, int csrno,
> target_ulong *val)
> {
> - *val = env->stimecmp;
> + if (riscv_cpu_virt_enabled(env)) {
> + *val = env->vstimecmp;
> + } else {
> + *val = env->stimecmp;
> + }
> +
> return RISCV_EXCP_NONE;
> }
>
> static RISCVException read_stimecmph(CPURISCVState *env, int csrno,
> target_ulong *val)
> {
> - *val = env->stimecmp >> 32;
> + if (riscv_cpu_virt_enabled(env)) {
> + *val = env->vstimecmp >> 32;
> + } else {
> + *val = env->stimecmp >> 32;
> + }
> +
> return RISCV_EXCP_NONE;
> }
>
> @@ -586,6 +679,10 @@ static RISCVException write_stimecmp(CPURISCVState *env,
> int csrno,
> {
> RISCVCPU *cpu = env_archcpu(env);
>
> + if (riscv_cpu_virt_enabled(env)) {
> + return write_vstimecmp(env, csrno, val);
> + }
> +
> if (riscv_cpu_mxl(env) == MXL_RV32) {
> env->stimecmp = deposit64(env->stimecmp, 0, 32, (uint64_t)val);
> env->stimecmp_wr_done |= 0x01;
> @@ -608,6 +705,10 @@ static RISCVException write_stimecmph(CPURISCVState
> *env, int csrno,
> {
> RISCVCPU *cpu = env_archcpu(env);
>
> + if (riscv_cpu_virt_enabled(env)) {
> + return write_vstimecmph(env, csrno, val);
> + }
> +
> env->stimecmp = deposit64(env->stimecmp, 32, 32, (uint64_t)val);
> env->stimecmp_wr_done |= 0x02;
> if (env->stimecmp_wr_done != 0x03) {
> @@ -1612,6 +1713,7 @@ static RISCVException rmw_mip64(CPURISCVState *env, int
> csrno,
> if (csrno != CSR_HVIP) {
> gin = get_field(env->hstatus, HSTATUS_VGEIN);
> old_mip |= (env->hgeip & ((target_ulong)1 << gin)) ? MIP_VSEIP : 0;
> + old_mip |= env->vstime_irq ? MIP_VSTIP : 0;
> }
>
> if (ret_val) {
> @@ -3433,6 +3535,12 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
> .min_priv_ver =
> PRIV_VERSION_1_12_0 },
> [CSR_STIMECMPH] = { "stimecmph", sstc, read_stimecmph, write_stimecmph,
> .min_priv_ver =
> PRIV_VERSION_1_12_0 },
> + [CSR_VSTIMECMP] = { "vstimecmp", sstc_hmode, read_vstimecmp,
> + write_vstimecmp,
> + .min_priv_ver =
> PRIV_VERSION_1_12_0 },
> + [CSR_VSTIMECMPH] = { "vstimecmph", sstc_hmode, read_vstimecmph,
> + write_vstimecmph,
> + .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 ee02bfc18916..d453b401bdfd 100644
> --- a/target/riscv/machine.c
> +++ b/target/riscv/machine.c
> @@ -92,6 +92,7 @@ static const VMStateDescription vmstate_hyper = {
> VMSTATE_UINTTL(env.hgeie, RISCVCPU),
> VMSTATE_UINTTL(env.hgeip, RISCVCPU),
> VMSTATE_UINT64(env.htimedelta, RISCVCPU),
> + VMSTATE_UINT64(env.vstimecmp, RISCVCPU),
Add vstimecmp_wr_done to vmstate_hyper.
>
> VMSTATE_UINTTL(env.hvictl, RISCVCPU),
> VMSTATE_UINT8_ARRAY(env.hviprio, RISCVCPU, 64),
> diff --git a/target/riscv/time_helper.c b/target/riscv/time_helper.c
> index f3fb5eac7b7b..8cce667dfd47 100644
> --- a/target/riscv/time_helper.c
> +++ b/target/riscv/time_helper.c
> @@ -22,6 +22,14 @@
> #include "time_helper.h"
> #include "hw/intc/riscv_aclint.h"
>
> +static void riscv_vstimer_cb(void *opaque)
> +{
> + RISCVCPU *cpu = opaque;
> + CPURISCVState *env = &cpu->env;
> + env->vstime_irq = 1;
> + riscv_cpu_update_mip(cpu, MIP_VSTIP, BOOL_TO_MASK(1));
> +}
> +
> static void riscv_stimer_cb(void *opaque)
> {
> RISCVCPU *cpu = opaque;
> @@ -47,10 +55,16 @@ void riscv_timer_write_timecmp(RISCVCPU *cpu, QEMUTimer
> *timer,
> * If we're setting an stimecmp value in the "past",
> * immediately raise the timer interrupt
> */
> + if (timer_irq == MIP_VSTIP) {
> + env->vstime_irq = 1;
> + }
> riscv_cpu_update_mip(cpu, timer_irq, BOOL_TO_MASK(1));
> return;
> }
>
> + if (timer_irq == MIP_VSTIP) {
> + env->vstime_irq = 0;
> + }
> /* Clear the [V]STIP bit in mip */
> riscv_cpu_update_mip(cpu, timer_irq, BOOL_TO_MASK(0));
>
> @@ -95,4 +109,6 @@ void riscv_timer_init(RISCVCPU *cpu)
> env->stimer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &riscv_stimer_cb, cpu);
> env->stimecmp = 0;
>
> + env->vstimer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &riscv_vstimer_cb, cpu);
> + env->vstimecmp = 0;
> }
> --
> 2.25.1
>
>
Regards,
Anup
