> -----Original Message-----
> From: Brian Cain <brian.c...@oss.qualcomm.com>
> Sent: Friday, February 28, 2025 11:28 PM
> To: qemu-devel@nongnu.org
> Cc: brian.c...@oss.qualcomm.com; richard.hender...@linaro.org;
> phi...@linaro.org; quic_mathb...@quicinc.com; a...@rev.ng; a...@rev.ng;
> quic_mlie...@quicinc.com; ltaylorsimp...@gmail.com;
> alex.ben...@linaro.org; quic_mbur...@quicinc.com;
> sidn...@quicinc.com; Brian Cain <bc...@quicinc.com>
> Subject: [PATCH 22/39] target/hexagon: Implement setprio, resched
>
> From: Brian Cain <bc...@quicinc.com>
>
> The hardware-assisted scheduler helps manage tasks on the run queue and
> interrupt steering.
>
> This instruction is defined in the Qualcomm Hexagon V71 Programmer's
> Reference Manual - https://docs.qualcomm.com/bundle/publicresource/80-
> N2040-51_REV_AB_Hexagon_V71_ProgrammerS_Reference_Manual.pdf
> See ยง11.9.2 SYSTEM MONITOR.
See earlier discussion on references to documents.
>
> Signed-off-by: Brian Cain <brian.c...@oss.qualcomm.com>
> ---
> target/hexagon/op_helper.c | 65
> ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 65 insertions(+)
>
> diff --git a/target/hexagon/op_helper.c b/target/hexagon/op_helper.c
> index 0dce133d3a..d0dc4afac7 100644
> --- a/target/hexagon/op_helper.c
> +++ b/target/hexagon/op_helper.c
> @@ -1465,6 +1465,57 @@ void HELPER(stop)(CPUHexagonState *env)
> hexagon_stop_thread(env);
> }
>
> +static inline QEMU_ALWAYS_INLINE void resched(CPUHexagonState *env)
> {
> + uint32_t schedcfg;
> + uint32_t schedcfg_en;
> + int int_number;
> + CPUState *cs;
> + uint32_t lowest_th_prio = 0; /* 0 is highest prio */
> + uint32_t bestwait_reg;
> + uint32_t best_prio;
> +
> + BQL_LOCK_GUARD();
> + qemu_log_mask(CPU_LOG_INT, "%s: check resched\n", __func__);
> + schedcfg = arch_get_system_reg(env, HEX_SREG_SCHEDCFG);
> + schedcfg_en = GET_FIELD(SCHEDCFG_EN, schedcfg);
> + int_number = GET_FIELD(SCHEDCFG_INTNO, schedcfg);
> +
> + if (!schedcfg_en) {
> + return;
> + }
> +
> + CPU_FOREACH(cs) {
> + HexagonCPU *thread = HEXAGON_CPU(cs);
> + CPUHexagonState *thread_env = &(thread->env);
> + uint32_t th_prio = GET_FIELD(
> + STID_PRIO, arch_get_system_reg(thread_env, HEX_SREG_STID));
> + if (!hexagon_thread_is_enabled(thread_env)) {
> + continue;
> + }
> +
> + lowest_th_prio = (lowest_th_prio > th_prio)
> + ? lowest_th_prio
> + : th_prio;
> + }
> +
> + bestwait_reg = arch_get_system_reg(env, HEX_SREG_BESTWAIT);
> + best_prio = GET_FIELD(BESTWAIT_PRIO, bestwait_reg);
> +
> + /*
> + * If the lowest priority thread is lower priority than the
> + * value in the BESTWAIT register, we must raise the reschedule
> + * interrupt on the lowest priority thread.
> + */
> + if (lowest_th_prio > best_prio) {
> + qemu_log_mask(CPU_LOG_INT,
> + "%s: raising resched int %d, cur PC 0x" TARGET_FMT_lx "\n",
> + __func__, int_number, arch_get_thread_reg(env, HEX_REG_PC));
> + SET_SYSTEM_FIELD(env, HEX_SREG_BESTWAIT, BESTWAIT_PRIO,
> 0x1ff);
What is the significance of 0x1ff? The field is 10 bits, so this isn't setting
all the bits.
Should this be lowest_th_prio?
> + hex_raise_interrupts(env, 1 << int_number, CPU_INTERRUPT_SWI);
> + }
> +}
> +
