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Diffstat (limited to 'arch/loongarch/kvm/timer.c')
| -rw-r--r-- | arch/loongarch/kvm/timer.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/arch/loongarch/kvm/timer.c b/arch/loongarch/kvm/timer.c new file mode 100644 index 000000000000..29c2aaba63c3 --- /dev/null +++ b/arch/loongarch/kvm/timer.c @@ -0,0 +1,193 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2020-2023 Loongson Technology Corporation Limited + */ + +#include <linux/kvm_host.h> +#include <asm/delay.h> +#include <asm/kvm_csr.h> +#include <asm/kvm_vcpu.h> + +/* + * ktime_to_tick() - Scale ktime_t to timer tick value. + */ +static inline u64 ktime_to_tick(struct kvm_vcpu *vcpu, ktime_t now) +{ + u64 delta; + + delta = ktime_to_ns(now); + return div_u64(delta * vcpu->arch.timer_mhz, MNSEC_PER_SEC); +} + +static inline u64 tick_to_ns(struct kvm_vcpu *vcpu, u64 tick) +{ + return div_u64(tick * MNSEC_PER_SEC, vcpu->arch.timer_mhz); +} + +/* 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, INT_TI); + rcuwait_wake_up(&vcpu->wait); + + return HRTIMER_NORESTART; +} + +/* + * Initialise the timer to the specified frequency, zero it + */ +void kvm_init_timer(struct kvm_vcpu *vcpu, unsigned long timer_hz) +{ + vcpu->arch.timer_mhz = timer_hz >> 20; + + /* Starting at 0 */ + kvm_write_sw_gcsr(vcpu->arch.csr, LOONGARCH_CSR_TVAL, 0); +} + +/* + * Restore soft timer state from saved context. + */ +void kvm_restore_timer(struct kvm_vcpu *vcpu) +{ + unsigned long cfg, estat; + unsigned long ticks, delta, period; + ktime_t expire, now; + struct loongarch_csrs *csr = vcpu->arch.csr; + + /* + * Set guest stable timer cfg csr + * Disable timer before restore estat CSR register, avoid to + * get invalid timer interrupt for old timer cfg + */ + cfg = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG); + + write_gcsr_timercfg(0); + kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_ESTAT); + kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_TCFG); + if (!(cfg & CSR_TCFG_EN)) { + /* Guest timer is disabled, just restore timer registers */ + kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_TVAL); + return; + } + + /* + * Freeze the soft-timer and sync the guest stable timer with it. + */ + if (kvm_vcpu_is_blocking(vcpu)) + hrtimer_cancel(&vcpu->arch.swtimer); + + /* + * From LoongArch Reference Manual Volume 1 Chapter 7.6.2 + * If oneshot timer is fired, CSR TVAL will be -1, there are two + * conditions: + * 1) timer is fired during exiting to host + * 2) timer is fired and vm is doing timer irq, and then exiting to + * host. Host should not inject timer irq to avoid spurious + * timer interrupt again + */ + ticks = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TVAL); + estat = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_ESTAT); + if (!(cfg & CSR_TCFG_PERIOD) && (ticks > cfg)) { + /* + * Writing 0 to LOONGARCH_CSR_TVAL will inject timer irq + * and set CSR TVAL with -1 + */ + write_gcsr_timertick(0); + __delay(2); /* Wait cycles until timer interrupt injected */ + + /* + * Writing CSR_TINTCLR_TI to LOONGARCH_CSR_TINTCLR will clear + * timer interrupt, and CSR TVAL keeps unchanged with -1, it + * avoids spurious timer interrupt + */ + if (!(estat & CPU_TIMER)) + gcsr_write(CSR_TINTCLR_TI, LOONGARCH_CSR_TINTCLR); + return; + } + + /* + * Set remainder tick value if not expired + */ + delta = 0; + now = ktime_get(); + expire = vcpu->arch.expire; + if (ktime_before(now, expire)) + delta = ktime_to_tick(vcpu, ktime_sub(expire, now)); + else if (cfg & CSR_TCFG_PERIOD) { + period = cfg & CSR_TCFG_VAL; + delta = ktime_to_tick(vcpu, ktime_sub(now, expire)); + delta = period - (delta % period); + + /* + * Inject timer here though sw timer should inject timer + * interrupt async already, since sw timer may be cancelled + * during injecting intr async + */ + kvm_queue_irq(vcpu, INT_TI); + } + + write_gcsr_timertick(delta); +} + +/* + * 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 void _kvm_save_timer(struct kvm_vcpu *vcpu) +{ + unsigned long ticks, delta, cfg; + ktime_t expire; + struct loongarch_csrs *csr = vcpu->arch.csr; + + cfg = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG); + ticks = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TVAL); + + /* + * From LoongArch Reference Manual Volume 1 Chapter 7.6.2 + * If period timer is fired, CSR TVAL will be reloaded from CSR TCFG + * If oneshot timer is fired, CSR TVAL will be -1 + * Here judge one-shot timer fired by checking whether TVAL is larger + * than TCFG + */ + if (ticks < cfg) + delta = tick_to_ns(vcpu, ticks); + else + delta = 0; + + expire = ktime_add_ns(ktime_get(), delta); + vcpu->arch.expire = expire; + if (kvm_vcpu_is_blocking(vcpu)) { + + /* + * HRTIMER_MODE_PINNED_HARD is suggested since vcpu may run in + * the same physical cpu in next time, and the timer should run + * in hardirq context even in the PREEMPT_RT case. + */ + hrtimer_start(&vcpu->arch.swtimer, expire, HRTIMER_MODE_ABS_PINNED_HARD); + } +} + +/* + * 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; + + preempt_disable(); + + /* Save hard timer state */ + kvm_save_hw_gcsr(csr, LOONGARCH_CSR_TCFG); + kvm_save_hw_gcsr(csr, LOONGARCH_CSR_TVAL); + if (kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG) & CSR_TCFG_EN) + _kvm_save_timer(vcpu); + + /* Save timer-related state to vCPU context */ + kvm_save_hw_gcsr(csr, LOONGARCH_CSR_ESTAT); + preempt_enable(); +} |