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Date: Tue, 11 Oct 2016 20:17:20 +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 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 | 83 +++++++++++++++++++++++++++++++++-------------------
1 file changed, 53 insertions(+), 30 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index dad743e..f9df9e3 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1101,13 +1101,20 @@ 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 (ktime_to_ns(remaining) < 0)
- remaining = ktime_set(0, 0);
+ if (kvm_lapic_hv_timer_in_use(apic->vcpu)) {
+ u64 tscl = rdtsc();
- ns = mod_64(ktime_to_ns(remaining), apic->lapic_timer.period);
- tmcct = div64_u64(ns,
- (APIC_BUS_CYCLE_NS * apic->divide_count));
+ tmcct = apic->lapic_timer.tscdeadline -
+ kvm_read_l1_tsc(apic->vcpu, tscl);
+ } else {
+ remaining = hrtimer_get_remaining(&apic->lapic_timer.timer);
+ if (ktime_to_ns(remaining) < 0)
+ remaining = ktime_set(0, 0);
+
+ ns = mod_64(ktime_to_ns(remaining), apic->lapic_timer.period);
+ tmcct = div64_u64(ns,
+ (APIC_BUS_CYCLE_NS * apic->divide_count));
+ }
return tmcct;
}
@@ -1400,52 +1407,65 @@ 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)
+static bool start_hv_timer(struct kvm_lapic *apic)
{
- struct kvm_lapic *apic = vcpu->arch.apic;
+ u64 tscdeadline;
- 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);
+ if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) {
+ u64 tscl = rdtsc();
-static bool start_hv_tscdeadline(struct kvm_lapic *apic)
-{
- u64 tscdeadline = apic->lapic_timer.tscdeadline;
+ apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT)
+ * APIC_BUS_CYCLE_NS * apic->divide_count;
+ apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) +
+ nsec_to_cycles(apic->vcpu, apic->lapic_timer.period);
+ }
+
+ tscdeadline = apic->lapic_timer.tscdeadline;
if (atomic_read(&apic->lapic_timer.pending) ||
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);
+ 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))
+ 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 +1477,15 @@ 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 +1493,11 @@ 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)) {
+ 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 +1735,7 @@ 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;
--
1.9.1
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