linux-kernel - Re: [PATCH v4 5/5] KVM: LAPIC: add advance timer support to pi_inject

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Message-ID: <CANRm+CwBY3xku7uE5fHRNBoHEctc1k-AS0DSny8jKKDsOUZs=g@mail.gmail.com>
Date:   Tue, 18 Jun 2019 08:57:15 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Radim Krčmář <rkrcmar@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Marcelo Tosatti <mtosatti@...hat.com>
Subject: Re: [PATCH v4 5/5] KVM: LAPIC: add advance timer support to pi_inject_timer

On Tue, 18 Jun 2019 at 08:44, Wanpeng Li <kernellwp@...il.com> wrote:
>
> On Tue, 18 Jun 2019 at 05:32, Radim Krčmář <rkrcmar@...hat.com> wrote:
> >
> > 2019-06-17 19:24+0800, Wanpeng Li:
> > > From: Wanpeng Li <wanpengli@...cent.com>
> > >
> > > Wait before calling posted-interrupt deliver function directly to add
> > > advance timer support to pi_inject_timer.
> > >
> > > Cc: Paolo Bonzini <pbonzini@...hat.com>
> > > Cc: Radim Krčmář <rkrcmar@...hat.com>
> > > Cc: Marcelo Tosatti <mtosatti@...hat.com>
> > > Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> > > ---
> >
> > Please merge this patch with [2/5], so bisection doesn't break.
>
> Agreed.
>
> >
> > >  arch/x86/kvm/lapic.c   | 6 ++++--
> > >  arch/x86/kvm/lapic.h   | 2 +-
> > >  arch/x86/kvm/svm.c     | 2 +-
> > >  arch/x86/kvm/vmx/vmx.c | 2 +-
> > >  4 files changed, 7 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> > > index 1a31389..1a31ba5 100644
> > > --- a/arch/x86/kvm/lapic.c
> > > +++ b/arch/x86/kvm/lapic.c
> > > @@ -1462,6 +1462,8 @@ static void apic_timer_expired(struct kvm_lapic *apic, bool can_pi_inject)
> > >               return;
> > >
> > >       if (can_pi_inject && posted_interrupt_inject_timer(apic->vcpu)) {
> > > +             if (apic->lapic_timer.timer_advance_ns)
> > > +                     kvm_wait_lapic_expire(vcpu, true);
> >
> > From where does kvm_wait_lapic_expire() take
> > apic->lapic_timer.expired_tscdeadline?
>
> Sorry, I failed to understand this.
> https://git.kernel.org/pub/scm/virt/kvm/kvm.git/tree/arch/x86/kvm/lapic.c?h=queue#n1541
> We can get apic->lapic_timer.expired_tscdeadline in
> kvm_wait_lapic_expire() directly.

Oh, miss the latest expired_tscdeadline, how about something like below?

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 1a31ba5..7cd95ea 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1461,6 +1461,9 @@ static void apic_timer_expired(struct kvm_lapic
*apic, bool can_pi_inject)
     if (atomic_read(&apic->lapic_timer.pending))
         return;

+    if (apic_lvtt_tscdeadline(apic) || ktimer->hv_timer_in_use)
+        ktimer->expired_tscdeadline = ktimer->tscdeadline;
+
     if (can_pi_inject && posted_interrupt_inject_timer(apic->vcpu)) {
         if (apic->lapic_timer.timer_advance_ns)
             kvm_wait_lapic_expire(vcpu, true);
@@ -1477,9 +1480,6 @@ static void apic_timer_expired(struct kvm_lapic
*apic, bool can_pi_inject)
      */
     if (swait_active(q))
         swake_up_one(q);
-
-    if (apic_lvtt_tscdeadline(apic) || ktimer->hv_timer_in_use)
-        ktimer->expired_tscdeadline = ktimer->tscdeadline;
 }

 /*