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Date: Tue, 28 Apr 2020 18:05:37 +0800
From: Wanpeng Li <kernellwp@...il.com>
To: 林鑫龙 <linxl3@...gsu.com>
Cc: LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
Haiwei Li <lihaiwei@...cent.com>
Subject: Re: [PATCH v4 6/7] KVM: X86: TSCDEADLINE MSR emulation fastpath
On Tue, 28 Apr 2020 at 17:59, 林鑫龙 <linxl3@...gsu.com> wrote:
>
> On Tuesday, 28 Apr 2020 at 14:23, Wanpeng Li <kernellwp@...il.com> wrote:
> >
> > From: Wanpeng Li <wanpengli@...cent.com>
> >
> > This patch implements tscdealine msr emulation fastpath, after wrmsr
> > tscdeadline vmexit, handle it as soon as possible and vmentry immediately
> > without checking various kvm stuff when possible.
> >
> > Tested-by: Haiwei Li <lihaiwei@...cent.com>
> > Cc: Haiwei Li <lihaiwei@...cent.com>
> > Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> > ---
> > arch/x86/kvm/lapic.c | 18 ++++++++++++------
> > arch/x86/kvm/vmx/vmx.c | 12 ++++++++----
> > arch/x86/kvm/x86.c | 30 ++++++++++++++++++++++++------
> > 3 files changed, 44 insertions(+), 16 deletions(-)
> >
> > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> > index 38f7dc9..3589237 100644
> > --- a/arch/x86/kvm/lapic.c
> > +++ b/arch/x86/kvm/lapic.c
> > @@ -1593,7 +1593,7 @@ static void kvm_apic_inject_pending_timer_irqs(struct kvm_lapic *apic)
> > }
> > }
> >
> > -static void apic_timer_expired(struct kvm_lapic *apic)
> > +static void apic_timer_expired(struct kvm_lapic *apic, bool from_timer_fn)
> > {
> > struct kvm_vcpu *vcpu = apic->vcpu;
> > struct kvm_timer *ktimer = &apic->lapic_timer;
> > @@ -1604,6 +1604,12 @@ static void apic_timer_expired(struct kvm_lapic *apic)
> > if (apic_lvtt_tscdeadline(apic) || ktimer->hv_timer_in_use)
> > ktimer->expired_tscdeadline = ktimer->tscdeadline;
> >
> > + if (!from_timer_fn && vcpu->arch.apicv_active) {
> > + WARN_ON(kvm_get_running_vcpu() != vcpu);
> > + kvm_apic_inject_pending_timer_irqs(apic);
> > + return;
> > + }
> > +
> > if (kvm_use_posted_timer_interrupt(apic->vcpu)) {
> > if (apic->lapic_timer.timer_advance_ns)
> > __kvm_wait_lapic_expire(vcpu);
> > @@ -1643,7 +1649,7 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic)
> > expire = ktime_sub_ns(expire, ktimer->timer_advance_ns);
> > hrtimer_start(&ktimer->timer, expire, HRTIMER_MODE_ABS_HARD);
> > } else
> > - apic_timer_expired(apic);
> > + apic_timer_expired(apic, false);
> >
> > local_irq_restore(flags);
> > }
> > @@ -1751,7 +1757,7 @@ static void start_sw_period(struct kvm_lapic *apic)
> >
> > if (ktime_after(ktime_get(),
> > apic->lapic_timer.target_expiration)) {
> > - apic_timer_expired(apic);
> > + apic_timer_expired(apic, false);
> >
> > if (apic_lvtt_oneshot(apic))
> > return;
> > @@ -1813,7 +1819,7 @@ static bool start_hv_timer(struct kvm_lapic *apic)
> > if (atomic_read(&ktimer->pending)) {
> > cancel_hv_timer(apic);
> > } else if (expired) {
> > - apic_timer_expired(apic);
> > + apic_timer_expired(apic, false);
> > cancel_hv_timer(apic);
> > }
> > }
> > @@ -1863,7 +1869,7 @@ void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu)
> > goto out;
> > WARN_ON(swait_active(&vcpu->wq));
> > cancel_hv_timer(apic);
> > - apic_timer_expired(apic);
> > + apic_timer_expired(apic, false);
> >
> > if (apic_lvtt_period(apic) && apic->lapic_timer.period) {
> > advance_periodic_target_expiration(apic);
> > @@ -2369,7 +2375,7 @@ static enum hrtimer_restart apic_timer_fn(struct hrtimer *data)
> > struct kvm_timer *ktimer = container_of(data, struct kvm_timer, timer);
> > struct kvm_lapic *apic = container_of(ktimer, struct kvm_lapic, lapic_timer);
> >
> > - apic_timer_expired(apic);
> > + apic_timer_expired(apic, true);
> >
> > if (lapic_is_periodic(apic)) {
> > advance_periodic_target_expiration(apic);
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > index ce19b0e..bb5c4f1 100644
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -5994,7 +5994,8 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
> > if (exit_fastpath == EXIT_FASTPATH_SKIP_EMUL_INS) {
> > kvm_skip_emulated_instruction(vcpu);
> Can we move this kvm_skip_emulated_instruction to handle_fastpath_set_msr_irqoff? This will keep the style consistent.
It can have other users sooner or later.
Wanpeng
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