diff options
| -rw-r--r-- | arch/x86/kvm/lapic.c | 57 | ||||
| -rw-r--r-- | arch/x86/kvm/lapic.h | 3 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 5 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.h | 2 |
4 files changed, 66 insertions, 1 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index fe8bae5..e1c0bef 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -33,6 +33,7 @@ #include <asm/page.h> #include <asm/current.h> #include <asm/apicdef.h> +#include <asm/delay.h> #include <linux/atomic.h> #include <linux/jump_label.h> #include "kvm_cache_regs.h" @@ -1073,6 +1074,7 @@ static void apic_timer_expired(struct kvm_lapic *apic) { struct kvm_vcpu *vcpu = apic->vcpu; wait_queue_head_t *q = &vcpu->wq; + struct kvm_timer *ktimer = &apic->lapic_timer; /* * Note: KVM_REQ_PENDING_TIMER is implicitly checked in @@ -1087,11 +1089,61 @@ static void apic_timer_expired(struct kvm_lapic *apic) if (waitqueue_active(q)) wake_up_interruptible(q); + + if (apic_lvtt_tscdeadline(apic)) + ktimer->expired_tscdeadline = ktimer->tscdeadline; +} + +/* + * On APICv, this test will cause a busy wait + * during a higher-priority task. + */ + +static bool lapic_timer_int_injected(struct kvm_vcpu *vcpu) +{ + struct kvm_lapic *apic = vcpu->arch.apic; + u32 reg = kvm_apic_get_reg(apic, APIC_LVTT); + + if (kvm_apic_hw_enabled(apic)) { + int vec = reg & APIC_VECTOR_MASK; + + if (kvm_x86_ops->test_posted_interrupt) + return kvm_x86_ops->test_posted_interrupt(vcpu, vec); + else { + if (apic_test_vector(vec, apic->regs + APIC_ISR)) + return true; + } + } + return false; +} + +void wait_lapic_expire(struct kvm_vcpu *vcpu) +{ + struct kvm_lapic *apic = vcpu->arch.apic; + u64 guest_tsc, tsc_deadline; + + if (!kvm_vcpu_has_lapic(vcpu)) + return; + + if (apic->lapic_timer.expired_tscdeadline == 0) + return; + + if (!lapic_timer_int_injected(vcpu)) + return; + + tsc_deadline = apic->lapic_timer.expired_tscdeadline; + apic->lapic_timer.expired_tscdeadline = 0; + guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu, native_read_tsc()); + + /* __delay is delay_tsc whenever the hardware has TSC, thus always. */ + if (guest_tsc < tsc_deadline) + __delay(tsc_deadline - guest_tsc); } static void start_apic_timer(struct kvm_lapic *apic) { ktime_t now; + atomic_set(&apic->lapic_timer.pending, 0); if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) { @@ -1137,6 +1189,7 @@ static void start_apic_timer(struct kvm_lapic *apic) /* lapic timer in tsc deadline mode */ u64 guest_tsc, tscdeadline = apic->lapic_timer.tscdeadline; u64 ns = 0; + ktime_t expire; struct kvm_vcpu *vcpu = apic->vcpu; unsigned long this_tsc_khz = vcpu->arch.virtual_tsc_khz; unsigned long flags; @@ -1151,8 +1204,10 @@ static void start_apic_timer(struct kvm_lapic *apic) if (likely(tscdeadline > guest_tsc)) { ns = (tscdeadline - guest_tsc) * 1000000ULL; do_div(ns, this_tsc_khz); + expire = ktime_add_ns(now, ns); + expire = ktime_sub_ns(expire, lapic_timer_advance_ns); hrtimer_start(&apic->lapic_timer.timer, - ktime_add_ns(now, ns), HRTIMER_MODE_ABS); + expire, HRTIMER_MODE_ABS); } else apic_timer_expired(apic); diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index c674fce..7054437 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -14,6 +14,7 @@ struct kvm_timer { u32 timer_mode; u32 timer_mode_mask; u64 tscdeadline; + u64 expired_tscdeadline; atomic_t pending; /* accumulated triggered timers */ }; @@ -170,4 +171,6 @@ static inline bool kvm_apic_has_events(struct kvm_vcpu *vcpu) bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector); +void wait_lapic_expire(struct kvm_vcpu *vcpu); + #endif diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index af9faed..559e3fd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -108,6 +108,10 @@ EXPORT_SYMBOL_GPL(kvm_max_guest_tsc_khz); static u32 tsc_tolerance_ppm = 250; module_param(tsc_tolerance_ppm, uint, S_IRUGO | S_IWUSR); +/* lapic timer advance (tscdeadline mode only) in nanoseconds */ +unsigned int lapic_timer_advance_ns = 0; +module_param(lapic_timer_advance_ns, uint, S_IRUGO | S_IWUSR); + static bool backwards_tsc_observed = false; #define KVM_NR_SHARED_MSRS 16 @@ -6312,6 +6316,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) } trace_kvm_entry(vcpu->vcpu_id); + wait_lapic_expire(vcpu); kvm_x86_ops->run(vcpu); /* diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index cc1d61a..07994f3 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -170,5 +170,7 @@ extern u64 kvm_supported_xcr0(void); extern unsigned int min_timer_period_us; +extern unsigned int lapic_timer_advance_ns; + extern struct static_key kvm_no_apic_vcpu; #endif |
