diff options
Diffstat (limited to 'arch/loongarch/kvm/timer.c')
| -rw-r--r-- | arch/loongarch/kvm/timer.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/arch/loongarch/kvm/timer.c b/arch/loongarch/kvm/timer.c new file mode 100644 index 000000000000..284bf553fefe --- /dev/null +++ b/arch/loongarch/kvm/timer.c @@ -0,0 +1,197 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2020-2023 Loongson Technology Corporation Limited + */ + +#include <linux/kvm_host.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); +} + +/* + * Push timer forward on timeout. + * Handle an hrtimer event by push the hrtimer forward a period. + */ +static enum hrtimer_restart kvm_count_timeout(struct kvm_vcpu *vcpu) +{ + unsigned long cfg, period; + + /* Add periodic tick to current expire time */ + cfg = kvm_read_sw_gcsr(vcpu->arch.csr, LOONGARCH_CSR_TCFG); + if (cfg & CSR_TCFG_PERIOD) { + period = tick_to_ns(vcpu, cfg & CSR_TCFG_VAL); + hrtimer_add_expires_ns(&vcpu->arch.swtimer, period); + return HRTIMER_RESTART; + } else + return HRTIMER_NORESTART; +} + +/* 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 kvm_count_timeout(vcpu); +} + +/* + * 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 hard timer state and enable guest to access timer registers + * without trap, should be called with irq disabled + */ +void kvm_acquire_timer(struct kvm_vcpu *vcpu) +{ + unsigned long cfg; + + cfg = read_csr_gcfg(); + if (!(cfg & CSR_GCFG_TIT)) + return; + + /* Enable guest access to hard timer */ + write_csr_gcfg(cfg & ~CSR_GCFG_TIT); + + /* + * Freeze the soft-timer and sync the guest stable timer with it. We do + * this with interrupts disabled to avoid latency. + */ + hrtimer_cancel(&vcpu->arch.swtimer); +} + +/* + * Restore soft timer state from saved context. + */ +void kvm_restore_timer(struct kvm_vcpu *vcpu) +{ + unsigned long cfg, delta, period; + ktime_t expire, now; + struct loongarch_csrs *csr = vcpu->arch.csr; + + /* + * Set guest stable timer cfg csr + */ + cfg = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG); + 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; + } + + /* + * Set remainder tick value if not expired + */ + 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); + } else + delta = 0; + /* + * Inject timer here though sw timer should inject timer + * interrupt async already, since sw timer may be cancelled + * during injecting intr async in function kvm_acquire_timer + */ + 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; + ktime_t expire; + struct loongarch_csrs *csr = vcpu->arch.csr; + + ticks = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TVAL); + delta = tick_to_ns(vcpu, ticks); + expire = ktime_add_ns(ktime_get(), delta); + vcpu->arch.expire = expire; + if (ticks) { + /* + * Update hrtimer to use new timeout + * HRTIMER_MODE_PINNED is suggested since vcpu may run in + * the same physical cpu in next time + */ + hrtimer_cancel(&vcpu->arch.swtimer); + hrtimer_start(&vcpu->arch.swtimer, expire, HRTIMER_MODE_ABS_PINNED); + } else + /* + * Inject timer interrupt so that hall polling can dectect and exit + */ + kvm_queue_irq(vcpu, INT_TI); +} + +/* + * Save guest timer state and switch to soft guest timer if hard timer was in + * use. + */ +void kvm_save_timer(struct kvm_vcpu *vcpu) +{ + unsigned long cfg; + struct loongarch_csrs *csr = vcpu->arch.csr; + + preempt_disable(); + cfg = read_csr_gcfg(); + if (!(cfg & CSR_GCFG_TIT)) { + /* Disable guest use of hard timer */ + write_csr_gcfg(cfg | CSR_GCFG_TIT); + + /* 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(); +} + +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); +} |