From e0ac535178ad32c2a4898e2309dcc49ad546e96e Mon Sep 17 00:00:00 2001
From: Wanpeng Li <wanpengli@tencent.com>
Date: Tue, 26 Apr 2022 01:25:51 -0700
Subject: [PATCH] KVM: LAPIC: Trace LAPIC timer expiration on every vmentry
In commit ec0671d5684a ("KVM: LAPIC: Delay trace_kvm_wait_lapic_expire
tracepoint to after vmexit", 2019-06-04), trace_kvm_wait_lapic_expire
was moved after guest_exit_irqoff() because invoking tracepoints within
kvm_guest_enter/kvm_guest_exit caused a lockdep splat.
These days this is not necessary, because commit 87fa7f3e98a1 ("x86/kvm:
Move context tracking where it belongs", 2020-07-09) restricted
the RCU extended quiescent state to be closer to vmentry/vmexit.
Moving the tracepoint back to __kvm_wait_lapic_expire is more accurate,
because it will be reported even if vcpu_enter_guest causes multiple
vmentries via the IPI/Timer fast paths, and it allows the removal of
advance_expire_delta.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1650961551-38390-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/lapic.c | 4 ++--
arch/x86/kvm/lapic.h | 1 -
arch/x86/kvm/x86.c | 8 --------
3 files changed, 2 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 66b0eb0bda94e..a4e9eb329e424 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1648,10 +1648,10 @@ static void __kvm_wait_lapic_expire(struct kvm_vcpu *vcpu)
tsc_deadline = apic->lapic_timer.expired_tscdeadline;
apic->lapic_timer.expired_tscdeadline = 0;
guest_tsc = kvm_read_l1_tsc(vcpu, rdtsc());
- apic->lapic_timer.advance_expire_delta = guest_tsc - tsc_deadline;
+ trace_kvm_wait_lapic_expire(vcpu->vcpu_id, guest_tsc - tsc_deadline);
if (lapic_timer_advance_dynamic) {
- adjust_lapic_timer_advance(vcpu, apic->lapic_timer.advance_expire_delta);
+ adjust_lapic_timer_advance(vcpu, guest_tsc - tsc_deadline);
/*
* If the timer fired early, reread the TSC to account for the
* overhead of the above adjustment to avoid waiting longer
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 4e4f8a22754f9..65bb2a8cf1459 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -38,7 +38,6 @@ struct kvm_timer {
u64 tscdeadline;
u64 expired_tscdeadline;
u32 timer_advance_ns;
- s64 advance_expire_delta;
atomic_t pending; /* accumulated triggered timers */
bool hv_timer_in_use;
};
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 476ea099ebf03..8b62c9b7795ef 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10310,14 +10310,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
*/
guest_timing_exit_irqoff();
- if (lapic_in_kernel(vcpu)) {
- s64 delta = vcpu->arch.apic->lapic_timer.advance_expire_delta;
- if (delta != S64_MIN) {
- trace_kvm_wait_lapic_expire(vcpu->vcpu_id, delta);
- vcpu->arch.apic->lapic_timer.advance_expire_delta = S64_MIN;
- }
- }
-
local_irq_enable();
preempt_enable();
--
2.30.2