From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
The kick after setting KVM_REQ_PENDING_TIMER is used to handle the timer
fires on a different pCPU which vCPU is running on, this kick is expensive
since memory barrier, rcu, preemption disable/enable operations. We don't
need this kick when injecting already-expired timer, we also should call
out the VMX preemption timer case, which also passes from_timer_fn=false
but doesn't need a kick because kvm_lapic_expired_hv_timer() is called
from the target vCPU.
Reviewed-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 4 +++-
arch/x86/kvm/x86.c | 6 ------
arch/x86/kvm/x86.h | 1 -
3 files changed, 3 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index e446bdf..3b32d3b 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1642,7 +1642,9 @@ static void apic_timer_expired(struct kvm_lapic *apic, bool from_timer_fn)
}
atomic_inc(&apic->lapic_timer.pending);
- kvm_set_pending_timer(vcpu);
+ kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu);
+ if (from_timer_fn)
+ kvm_vcpu_kick(vcpu);
}
static void start_sw_tscdeadline(struct kvm_lapic *apic)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d39d6cf..dcf4494 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1774,12 +1774,6 @@ static s64 get_kvmclock_base_ns(void)
}
#endif
-void kvm_set_pending_timer(struct kvm_vcpu *vcpu)
-{
- kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu);
- kvm_vcpu_kick(vcpu);
-}
-
static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock)
{
int version;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 995ab69..ea20b8b 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -246,7 +246,6 @@ static inline bool kvm_vcpu_latch_init(struct kvm_vcpu *vcpu)
return is_smm(vcpu) || kvm_x86_ops.apic_init_signal_blocked(vcpu);
}
-void kvm_set_pending_timer(struct kvm_vcpu *vcpu);
void kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip);
void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr);
--
2.7.4
