From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
Introduce set_target_expiration() to set target expiration time which is
when LVTT current-count register counts down to zero and a timer interrupt
is generated.
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Cc: Yunhong Jiang <yunhong.jiang@xxxxxxxxx>
Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/lapic.h | 1 +
2 files changed, 48 insertions(+)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index dce6c0b..09dad85 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1391,6 +1391,53 @@ static void start_sw_period(struct kvm_lapic *apic)
apic->lapic_timer.period)));
}
+static bool set_target_expiration(struct kvm_lapic *apic)
+{
+ ktime_t now;
+ u64 tscl = rdtsc();
+
+ now = apic->lapic_timer.timer.base->get_time();
+ apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT)
+ * APIC_BUS_CYCLE_NS * apic->divide_count;
+
+ if (!apic->lapic_timer.period)
+ return false;
+
+ /*
+ * Do not allow the guest to program periodic timers with small
+ * interval, since the hrtimers are not throttled by the host
+ * scheduler.
+ */
+ if (apic_lvtt_period(apic)) {
+ s64 min_period = min_timer_period_us * 1000LL;
+
+ if (apic->lapic_timer.period < min_period) {
+ pr_info_ratelimited(
+ "kvm: vcpu %i: requested %lld ns "
+ "lapic timer period limited to %lld ns\n",
+ apic->vcpu->vcpu_id,
+ apic->lapic_timer.period, min_period);
+ apic->lapic_timer.period = min_period;
+ }
+ }
+
+ apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016"
+ PRIx64 ", "
+ "timer initial count 0x%x, period %lldns, "
+ "expire @ 0x%016" PRIx64 ".\n", __func__,
+ APIC_BUS_CYCLE_NS, ktime_to_ns(now),
+ kvm_lapic_get_reg(apic, APIC_TMICT),
+ apic->lapic_timer.period,
+ ktime_to_ns(ktime_add_ns(now,
+ apic->lapic_timer.period)));
+
+ apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) +
+ nsec_to_cycles(apic->vcpu, apic->lapic_timer.period);
+ apic->lapic_timer.target_expiration = ktime_add_ns(now, apic->lapic_timer.period);
+
+ return true;
+}
+
bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu)
{
if (!lapic_in_kernel(vcpu))
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index f60d01c..889b504 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -15,6 +15,7 @@
struct kvm_timer {
struct hrtimer timer;
s64 period; /* unit: ns */
+ ktime_t target_expiration;
u32 timer_mode;
u32 timer_mode_mask;
u64 tscdeadline;
--
1.9.1
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