From patchwork Tue Mar 21 03:56:40 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: zhaotianrui X-Patchwork-Id: 13182207 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93BA7C76195 for ; Tue, 21 Mar 2023 03:57:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230051AbjCUD54 (ORCPT ); Mon, 20 Mar 2023 23:57:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229892AbjCUD5X (ORCPT ); Mon, 20 Mar 2023 23:57:23 -0400 Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 978CB32CF1; Mon, 20 Mar 2023 20:57:05 -0700 (PDT) Received: from loongson.cn (unknown [10.2.5.185]) by gateway (Coremail) with SMTP id _____8AxYcwPKxlkpTYPAA--.22618S3; Tue, 21 Mar 2023 11:57:03 +0800 (CST) Received: from localhost.localdomain (unknown [10.2.5.185]) by localhost.localdomain (Coremail) with SMTP id AQAAf8DxD78EKxlkQB4IAA--.33942S20; Tue, 21 Mar 2023 11:57:02 +0800 (CST) From: Tianrui Zhao To: Paolo Bonzini Cc: Huacai Chen , WANG Xuerui , Greg Kroah-Hartman , loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Jens Axboe , Mark Brown , Alex Deucher , Oliver Upton , maobibo@loongson.cn, Xi Ruoyao Subject: [PATCH v4 18/29] LoongArch: KVM: Implement vcpu timer operations Date: Tue, 21 Mar 2023 11:56:40 +0800 Message-Id: <20230321035651.598505-19-zhaotianrui@loongson.cn> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230321035651.598505-1-zhaotianrui@loongson.cn> References: <20230321035651.598505-1-zhaotianrui@loongson.cn> MIME-Version: 1.0 X-CM-TRANSID: AQAAf8DxD78EKxlkQB4IAA--.33942S20 X-CM-SenderInfo: p2kd03xldq233l6o00pqjv00gofq/ X-Coremail-Antispam: 1Uk129KBjvJXoWxtw1UCF1fuF43ArykXw47Jwb_yoW3Zw1xpr WIkryIqr48Xryqgwn3AFs0vrn8W3yrKw17Gry7J3ySyrnxJ3s8XF40gryDJFZxGFyIvF1S vryrAwn8Ar4kA3DanT9S1TB71UUUUjJqnTZGkaVYY2UrUUUUj1kv1TuYvTs0mT0YCTnIWj qI5I8CrVACY4xI64kE6c02F40Ex7xfYxn0WfASr-VFAUDa7-sFnT9fnUUIcSsGvfJTRUUU bxxFc2x0x2IEx4CE42xK8VAvwI8IcIk0rVWrJVCq3wA2ocxC64kIII0Yj41l84x0c7CEw4 AK67xGY2AK021l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF 7I0E14v26r4UJVWxJr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aV CY1x0267AKxVW8Jr0_Cr1UM2kKe7AKxVWUAVWUtwAS0I0E0xvYzxvE52x082IY62kv0487 Mc804VCY07AIYIkI8VC2zVCFFI0UMc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VCjz48v1s IEY20_WwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lc7CjxVAaw2AFwI0_ JF0_Jw1l42xK82IYc2Ij64vIr41l42xK82IY6x8ErcxFaVAv8VWrMxC20s026xCaFVCjc4 AY6r1j6r4UMxCIbckI1I0E14v26r126r1DMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCj r7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6x IIjxv20xvE14v26w1j6s0DMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UMIIF0xvE 42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVW8Jr0_Cr1UMIIF0xvEx4A2js IEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIevJa73UjIFyTuYvj4RKpBTUUUUU Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Implement loongarch vcpu timer operations such as init kvm timer, require kvm timer, save kvm timer and restore kvm timer. When vcpu exit, we use kvm soft timer to emulate hardware timer. If timeout happens, the vcpu timer interrupt will be set and it is going to be handled at vcpu next entrance. Signed-off-by: Tianrui Zhao --- arch/loongarch/kvm/timer.c | 266 +++++++++++++++++++++++++++++++++++++ 1 file changed, 266 insertions(+) create mode 100644 arch/loongarch/kvm/timer.c diff --git a/arch/loongarch/kvm/timer.c b/arch/loongarch/kvm/timer.c new file mode 100644 index 000000000..2c7677248 --- /dev/null +++ b/arch/loongarch/kvm/timer.c @@ -0,0 +1,266 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2020-2023 Loongson Technology Corporation Limited + */ + +#include +#include +#include + +/* low level hrtimer wake routine */ +enum hrtimer_restart kvm_swtimer_wakeup(struct hrtimer *timer) +{ + struct kvm_vcpu *vcpu; + + vcpu = container_of(timer, struct kvm_vcpu, arch.swtimer); + _kvm_queue_irq(vcpu, LARCH_INT_TIMER); + rcuwait_wake_up(&vcpu->wait); + return kvm_count_timeout(vcpu); +} + +/* + * ktime_to_tick() - Scale ktime_t to a 64-bit stable timer. + * + * Caches the dynamic nanosecond bias in vcpu->arch.timer_dyn_bias. + */ +static unsigned long ktime_to_tick(struct kvm_vcpu *vcpu, ktime_t now) +{ + s64 now_ns, periods; + unsigned long delta; + + now_ns = ktime_to_ns(now); + delta = now_ns + vcpu->arch.timer_dyn_bias; + + if (delta >= vcpu->arch.timer_period) { + /* If delta is out of safe range the bias needs adjusting */ + periods = div64_s64(now_ns, vcpu->arch.timer_period); + vcpu->arch.timer_dyn_bias = -periods * vcpu->arch.timer_period; + /* Recalculate delta with new bias */ + delta = now_ns + vcpu->arch.timer_dyn_bias; + } + + /* + * We've ensured that: + * delta < timer_period + */ + return div_u64(delta * vcpu->arch.timer_mhz, MNSEC_PER_SEC); +} + +/** + * kvm_resume_hrtimer() - Resume hrtimer, updating expiry. + * @vcpu: Virtual CPU. + * @now: ktime at point of resume. + * @val: stable timer at point of resume. + * + * Resumes the timer and updates the timer expiry based on @now and @count. + */ +static void kvm_resume_hrtimer(struct kvm_vcpu *vcpu, ktime_t now, + unsigned long val) +{ + unsigned long delta; + ktime_t expire; + + /* Stable timer decreased to zero or + * initialize to zero, set 4 second timer + */ + delta = div_u64(val * MNSEC_PER_SEC, vcpu->arch.timer_mhz); + expire = ktime_add_ns(now, delta); + + /* Update hrtimer to use new timeout */ + hrtimer_cancel(&vcpu->arch.swtimer); + hrtimer_start(&vcpu->arch.swtimer, expire, HRTIMER_MODE_ABS_PINNED); +} + +/** + * kvm_init_timer() - Initialise stable timer. + * @vcpu: Virtual CPU. + * @timer_hz: Frequency of timer. + * + * Initialise the timer to the specified frequency, zero it, and set it going if + * it's enabled. + */ +void kvm_init_timer(struct kvm_vcpu *vcpu, unsigned long timer_hz) +{ + ktime_t now; + unsigned long ticks; + struct loongarch_csrs *csr = vcpu->arch.csr; + + ticks = (unsigned long)MNSEC_PER_SEC * CSR_TCFG_VAL; + vcpu->arch.timer_mhz = timer_hz >> 20; + vcpu->arch.timer_period = div_u64(ticks, vcpu->arch.timer_mhz); + vcpu->arch.timer_dyn_bias = 0; + + /* Starting at 0 */ + ticks = 0; + now = ktime_get(); + vcpu->arch.timer_bias = ticks - ktime_to_tick(vcpu, now); + vcpu->arch.timer_bias &= CSR_TCFG_VAL; + kvm_write_sw_gcsr(csr, LOONGARCH_CSR_TVAL, ticks); +} + +/** + * kvm_count_timeout() - Push timer forward on timeout. + * @vcpu: Virtual CPU. + * + * Handle an hrtimer event by push the hrtimer forward a period. + * + * Returns: The hrtimer_restart value to return to the hrtimer subsystem. + */ +enum hrtimer_restart kvm_count_timeout(struct kvm_vcpu *vcpu) +{ + unsigned long cfg; + + /* Add the Count period to the current expiry time */ + cfg = kvm_read_sw_gcsr(vcpu->arch.csr, LOONGARCH_CSR_TCFG); + if (cfg & CSR_TCFG_PERIOD) { + hrtimer_add_expires_ns(&vcpu->arch.swtimer, cfg & CSR_TCFG_VAL); + return HRTIMER_RESTART; + } else + return HRTIMER_NORESTART; +} + +/* + * kvm_restore_timer() - Restore timer state. + * @vcpu: Virtual CPU. + * + * Restore soft timer state from saved context. + */ +void kvm_restore_timer(struct kvm_vcpu *vcpu) +{ + struct loongarch_csrs *csr = vcpu->arch.csr; + ktime_t saved_ktime, now; + unsigned long val, new, delta; + int expired = 0; + unsigned long cfg; + + /* + * Set guest stable timer cfg csr + */ + cfg = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG); + kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_ESTAT); + if (!(cfg & CSR_TCFG_EN)) { + kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_TCFG); + kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_TVAL); + return; + } + + now = ktime_get(); + saved_ktime = vcpu->arch.stable_ktime_saved; + val = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TVAL); + + /*hrtimer not expire */ + delta = ktime_to_tick(vcpu, ktime_sub(now, saved_ktime)); + if (delta >= val) { + expired = 1; + if (cfg & CSR_TCFG_PERIOD) + new = (delta - val) % (cfg & CSR_TCFG_VAL); + else + new = 1; + } else + new = val - delta; + + new &= CSR_TCFG_VAL; + write_gcsr_timercfg(cfg); + write_gcsr_timertick(new); + if (expired) + _kvm_queue_irq(vcpu, LARCH_INT_TIMER); +} + +/* + * kvm_acquire_timer() - Switch to hard timer state. + * @vcpu: Virtual CPU. + * + * Restore hard timer state on top of existing soft timer state if possible. + * + * Since hard timer won't remain active over preemption, preemption should be + * disabled by the caller. + */ +void kvm_acquire_timer(struct kvm_vcpu *vcpu) +{ + unsigned long flags, guestcfg; + + guestcfg = read_csr_gcfg(); + if (!(guestcfg & CSR_GCFG_TIT)) + return; + + /* enable guest access to hard timer */ + write_csr_gcfg(guestcfg & ~CSR_GCFG_TIT); + + /* + * Freeze the soft-timer and sync the guest stable timer with it. We do + * this with interrupts disabled to avoid latency. + */ + local_irq_save(flags); + hrtimer_cancel(&vcpu->arch.swtimer); + local_irq_restore(flags); +} + + +/* + * _kvm_save_timer() - Switch to software emulation of guest timer. + * @vcpu: Virtual CPU. + * + * Save guest timer state and switch to software emulation of guest + * timer. The hard timer must already be in use, so preemption should be + * disabled. + */ +static ktime_t _kvm_save_timer(struct kvm_vcpu *vcpu, unsigned long *val) +{ + unsigned long end_time; + ktime_t before_time; + + before_time = ktime_get(); + + /* + * Record a final stable timer which we will transfer to the soft-timer. + */ + end_time = read_gcsr_timertick(); + *val = end_time; + + kvm_resume_hrtimer(vcpu, before_time, end_time); + return before_time; +} + +/* + * kvm_save_timer() - Save guest timer state. + * @vcpu: Virtual CPU. + * + * Save guest timer state and switch to soft guest timer if hard timer was in + * use. + */ +void kvm_save_timer(struct kvm_vcpu *vcpu) +{ + struct loongarch_csrs *csr = vcpu->arch.csr; + unsigned long guestcfg, val; + ktime_t save_ktime; + + preempt_disable(); + guestcfg = read_csr_gcfg(); + if (!(guestcfg & CSR_GCFG_TIT)) { + /* disable guest use of hard timer */ + write_csr_gcfg(guestcfg | CSR_GCFG_TIT); + + /* save hard timer state */ + kvm_save_hw_gcsr(csr, LOONGARCH_CSR_TCFG); + if (kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG) & CSR_TCFG_EN) { + save_ktime = _kvm_save_timer(vcpu, &val); + kvm_write_sw_gcsr(csr, LOONGARCH_CSR_TVAL, val); + vcpu->arch.stable_ktime_saved = save_ktime; + if (val == CSR_TCFG_VAL) + _kvm_queue_irq(vcpu, LARCH_INT_TIMER); + } else { + kvm_save_hw_gcsr(csr, LOONGARCH_CSR_TVAL); + } + } + + /* save timer-related state to VCPU context */ + kvm_save_hw_gcsr(csr, LOONGARCH_CSR_ESTAT); + preempt_enable(); +} + +void kvm_reset_timer(struct kvm_vcpu *vcpu) +{ + write_gcsr_timercfg(0); + kvm_write_sw_gcsr(vcpu->arch.csr, LOONGARCH_CSR_TCFG, 0); + hrtimer_cancel(&vcpu->arch.swtimer); +}