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Date: Wed, 12 Oct 2016 14:52:52 +0800
From: Wanpeng Li <kernellwp@...il.com>
To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Radim Krčmář <rkrcmar@...hat.com>,
Yunhong Jiang <yunhong.jiang@...el.com>,
Wanpeng Li <wanpeng.li@...mail.com>
Subject: [PATCH RFC V2 2/2] KVM: x86: Support using the VMX preemption timer for APIC Timer periodic/oneshot mode
From: Wanpeng Li <wanpeng.li@...mail.com>
Most windows guests still utilize APIC Timer periodic/oneshot mode
instead of tsc-deadline mode, and the APIC Timer periodic/oneshot
mode are still emulated by high overhead hrtimer on host. This patch
converts the expected expire time of the periodic/oneshot mode to
guest deadline tsc in order to leverage VMX preemption timer logic
for APIC Timer tsc-deadline mode.
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Yunhong Jiang <yunhong.jiang@...el.com>
Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
---
arch/x86/kvm/lapic.c | 103 +++++++++++++++++++++++++++++++++++----------------
arch/x86/kvm/lapic.h | 1 +
2 files changed, 73 insertions(+), 31 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index dad743e..f5a03ae 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1101,7 +1101,14 @@ static u32 apic_get_tmcct(struct kvm_lapic *apic)
apic->lapic_timer.period == 0)
return 0;
- remaining = hrtimer_get_remaining(&apic->lapic_timer.timer);
+ if (kvm_lapic_hv_timer_in_use(apic->vcpu)) {
+ ktime_t now;
+
+ now = apic->lapic_timer.timer.base->get_time();
+ remaining = ktime_sub(apic->lapic_timer.expired_period, now);
+ } else
+ remaining = hrtimer_get_remaining(&apic->lapic_timer.timer);
+
if (ktime_to_ns(remaining) < 0)
remaining = ktime_set(0, 0);
@@ -1353,8 +1360,6 @@ static void start_sw_period(struct kvm_lapic *apic)
/* lapic timer in oneshot or periodic mode */
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;
@@ -1377,7 +1382,7 @@ static void start_sw_period(struct kvm_lapic *apic)
}
hrtimer_start(&apic->lapic_timer.timer,
- ktime_add_ns(now, apic->lapic_timer.period),
+ apic->lapic_timer.expired_period,
HRTIMER_MODE_ABS_PINNED);
apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016"
@@ -1400,52 +1405,71 @@ bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL_GPL(kvm_lapic_hv_timer_in_use);
-static void cancel_hv_tscdeadline(struct kvm_lapic *apic)
+static void cancel_hv_timer(struct kvm_lapic *apic)
{
kvm_x86_ops->cancel_hv_timer(apic->vcpu);
apic->lapic_timer.hv_timer_in_use = false;
}
-void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu)
-{
- struct kvm_lapic *apic = vcpu->arch.apic;
-
- WARN_ON(!apic->lapic_timer.hv_timer_in_use);
- WARN_ON(swait_active(&vcpu->wq));
- cancel_hv_tscdeadline(apic);
- apic_timer_expired(apic);
-}
-EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer);
-
-static bool start_hv_tscdeadline(struct kvm_lapic *apic)
+static bool start_hv_timer(struct kvm_lapic *apic)
{
u64 tscdeadline = apic->lapic_timer.tscdeadline;
- if (atomic_read(&apic->lapic_timer.pending) ||
+ if ((atomic_read(&apic->lapic_timer.pending) &&
+ !apic_lvtt_period(apic)) ||
kvm_x86_ops->set_hv_timer(apic->vcpu, tscdeadline)) {
if (apic->lapic_timer.hv_timer_in_use)
- cancel_hv_tscdeadline(apic);
+ cancel_hv_timer(apic);
} else {
apic->lapic_timer.hv_timer_in_use = true;
hrtimer_cancel(&apic->lapic_timer.timer);
/* In case the sw timer triggered in the window */
- if (atomic_read(&apic->lapic_timer.pending))
- cancel_hv_tscdeadline(apic);
+ if (atomic_read(&apic->lapic_timer.pending) &&
+ !apic_lvtt_period(apic))
+ cancel_hv_timer(apic);
}
trace_kvm_hv_timer_state(apic->vcpu->vcpu_id,
apic->lapic_timer.hv_timer_in_use);
return apic->lapic_timer.hv_timer_in_use;
}
+void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu)
+{
+ struct kvm_lapic *apic = vcpu->arch.apic;
+
+ WARN_ON(!apic->lapic_timer.hv_timer_in_use);
+ WARN_ON(swait_active(&vcpu->wq));
+ cancel_hv_timer(apic);
+ apic_timer_expired(apic);
+
+ if (apic_lvtt_period(apic)) {
+ ktime_t now;
+ u64 tscl = rdtsc();
+
+ 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;
+
+ apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) +
+ nsec_to_cycles(apic->vcpu, apic->lapic_timer.period);
+ now = apic->lapic_timer.timer.base->get_time();
+ apic->lapic_timer.expired_period = ktime_add_ns(now, apic->lapic_timer.period);
+
+ start_hv_timer(apic);
+ }
+}
+EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer);
+
void kvm_lapic_switch_to_hv_timer(struct kvm_vcpu *vcpu)
{
struct kvm_lapic *apic = vcpu->arch.apic;
WARN_ON(apic->lapic_timer.hv_timer_in_use);
- if (apic_lvtt_tscdeadline(apic))
- start_hv_tscdeadline(apic);
+ start_hv_timer(apic);
}
EXPORT_SYMBOL_GPL(kvm_lapic_switch_to_hv_timer);
@@ -1457,12 +1481,15 @@ void kvm_lapic_switch_to_sw_timer(struct kvm_vcpu *vcpu)
if (!apic->lapic_timer.hv_timer_in_use)
return;
- cancel_hv_tscdeadline(apic);
+ cancel_hv_timer(apic);
if (atomic_read(&apic->lapic_timer.pending))
return;
- start_sw_tscdeadline(apic);
+ if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic))
+ start_sw_period(apic);
+ else if (apic_lvtt_tscdeadline(apic))
+ start_sw_tscdeadline(apic);
}
EXPORT_SYMBOL_GPL(kvm_lapic_switch_to_sw_timer);
@@ -1470,10 +1497,25 @@ static void start_apic_timer(struct kvm_lapic *apic)
{
atomic_set(&apic->lapic_timer.pending, 0);
- if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic))
- start_sw_period(apic);
- else if (apic_lvtt_tscdeadline(apic)) {
- if (!(kvm_x86_ops->set_hv_timer && start_hv_tscdeadline(apic)))
+ if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) {
+ ktime_t now;
+ u64 tscl = rdtsc();
+
+ 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;
+
+ apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) +
+ nsec_to_cycles(apic->vcpu, apic->lapic_timer.period);
+ now = apic->lapic_timer.timer.base->get_time();
+ apic->lapic_timer.expired_period = ktime_add_ns(now, apic->lapic_timer.period);
+
+ if (!(kvm_x86_ops->set_hv_timer && start_hv_timer(apic)))
+ start_sw_period(apic);
+ } else if (apic_lvtt_tscdeadline(apic)) {
+ if (!(kvm_x86_ops->set_hv_timer && start_hv_timer(apic)))
start_sw_tscdeadline(apic);
}
}
@@ -1711,8 +1753,7 @@ u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu)
{
struct kvm_lapic *apic = vcpu->arch.apic;
- if (!lapic_in_kernel(vcpu) || apic_lvtt_oneshot(apic) ||
- apic_lvtt_period(apic))
+ if (!lapic_in_kernel(vcpu))
return 0;
return apic->lapic_timer.tscdeadline;
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index f60d01c..fea7602 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 expired_period;
u32 timer_mode;
u32 timer_mode_mask;
u64 tscdeadline;
--
1.9.1
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