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From:   Wanpeng Li <kernellwp@gmail.com>
Date:   Tue, 28 Apr 2020 18:05:37 +0800
Message-ID: <CANRm+Cw0=JU5eJayQ0XM7n2e+q8a8dzHusqtsfNjmWTNai9phg@mail.gmail.com>
Subject: Re: [PATCH v4 6/7] KVM: X86: TSCDEADLINE MSR emulation fastpath
To:     =?UTF-8?B?5p6X6ZGr6b6Z?= <linxl3@wangsu.com>
Cc:     LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Haiwei Li <lihaiwei@tencent.com>
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On Tue, 28 Apr 2020 at 17:59, =E6=9E=97=E9=91=AB=E9=BE=99 <linxl3@wangsu.co=
m> wrote:
>
> On Tuesday, 28 Apr 2020 at 14:23, Wanpeng Li <kernellwp@gmail.com> wrote:
> &gt;
> &gt; From: Wanpeng Li <wanpengli@tencent.com>
> &gt;
> &gt; This patch implements tscdealine msr emulation fastpath, after wrmsr
> &gt; tscdeadline vmexit, handle it as soon as possible and vmentry immedi=
ately
> &gt; without checking various kvm stuff when possible.
> &gt;
> &gt; Tested-by: Haiwei Li <lihaiwei@tencent.com>
> &gt; Cc: Haiwei Li <lihaiwei@tencent.com>
> &gt; Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> &gt; ---
> &gt;  arch/x86/kvm/lapic.c   | 18 ++++++++++++------
> &gt;  arch/x86/kvm/vmx/vmx.c | 12 ++++++++----
> &gt;  arch/x86/kvm/x86.c     | 30 ++++++++++++++++++++++++------
> &gt;  3 files changed, 44 insertions(+), 16 deletions(-)
> &gt;
> &gt; diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> &gt; index 38f7dc9..3589237 100644
> &gt; --- a/arch/x86/kvm/lapic.c
> &gt; +++ b/arch/x86/kvm/lapic.c
> &gt; @@ -1593,7 +1593,7 @@ static void kvm_apic_inject_pending_timer_irqs=
(struct kvm_lapic *apic)
> &gt;    }
> &gt;  }
> &gt;
> &gt; -static void apic_timer_expired(struct kvm_lapic *apic)
> &gt; +static void apic_timer_expired(struct kvm_lapic *apic, bool from_ti=
mer_fn)
> &gt;  {
> &gt;    struct kvm_vcpu *vcpu =3D apic-&gt;vcpu;
> &gt;    struct kvm_timer *ktimer =3D &amp;apic-&gt;lapic_timer;
> &gt; @@ -1604,6 +1604,12 @@ static void apic_timer_expired(struct kvm_lap=
ic *apic)
> &gt;    if (apic_lvtt_tscdeadline(apic) || ktimer-&gt;hv_timer_in_use)
> &gt;            ktimer-&gt;expired_tscdeadline =3D ktimer-&gt;tscdeadline=
;
> &gt;
> &gt; +  if (!from_timer_fn &amp;&amp; vcpu-&gt;arch.apicv_active) {
> &gt; +          WARN_ON(kvm_get_running_vcpu() !=3D vcpu);
> &gt; +          kvm_apic_inject_pending_timer_irqs(apic);
> &gt; +          return;
> &gt; +  }
> &gt; +
> &gt;    if (kvm_use_posted_timer_interrupt(apic-&gt;vcpu)) {
> &gt;            if (apic-&gt;lapic_timer.timer_advance_ns)
> &gt;                    __kvm_wait_lapic_expire(vcpu);
> &gt; @@ -1643,7 +1649,7 @@ static void start_sw_tscdeadline(struct kvm_la=
pic *apic)
> &gt;            expire =3D ktime_sub_ns(expire, ktimer-&gt;timer_advance_=
ns);
> &gt;            hrtimer_start(&amp;ktimer-&gt;timer, expire, HRTIMER_MODE=
_ABS_HARD);
> &gt;    } else
> &gt; -          apic_timer_expired(apic);
> &gt; +          apic_timer_expired(apic, false);
> &gt;
> &gt;    local_irq_restore(flags);
> &gt;  }
> &gt; @@ -1751,7 +1757,7 @@ static void start_sw_period(struct kvm_lapic *=
apic)
> &gt;
> &gt;    if (ktime_after(ktime_get(),
> &gt;                    apic-&gt;lapic_timer.target_expiration)) {
> &gt; -          apic_timer_expired(apic);
> &gt; +          apic_timer_expired(apic, false);
> &gt;
> &gt;            if (apic_lvtt_oneshot(apic))
> &gt;                    return;
> &gt; @@ -1813,7 +1819,7 @@ static bool start_hv_timer(struct kvm_lapic *a=
pic)
> &gt;            if (atomic_read(&amp;ktimer-&gt;pending)) {
> &gt;                    cancel_hv_timer(apic);
> &gt;            } else if (expired) {
> &gt; -                  apic_timer_expired(apic);
> &gt; +                  apic_timer_expired(apic, false);
> &gt;                    cancel_hv_timer(apic);
> &gt;            }
> &gt;    }
> &gt; @@ -1863,7 +1869,7 @@ void kvm_lapic_expired_hv_timer(struct kvm_vcp=
u *vcpu)
> &gt;            goto out;
> &gt;    WARN_ON(swait_active(&amp;vcpu-&gt;wq));
> &gt;    cancel_hv_timer(apic);
> &gt; -  apic_timer_expired(apic);
> &gt; +  apic_timer_expired(apic, false);
> &gt;
> &gt;    if (apic_lvtt_period(apic) &amp;&amp; apic-&gt;lapic_timer.period=
) {
> &gt;            advance_periodic_target_expiration(apic);
> &gt; @@ -2369,7 +2375,7 @@ static enum hrtimer_restart apic_timer_fn(stru=
ct hrtimer *data)
> &gt;    struct kvm_timer *ktimer =3D container_of(data, struct kvm_timer,=
 timer);
> &gt;    struct kvm_lapic *apic =3D container_of(ktimer, struct kvm_lapic,=
 lapic_timer);
> &gt;
> &gt; -  apic_timer_expired(apic);
> &gt; +  apic_timer_expired(apic, true);
> &gt;
> &gt;    if (lapic_is_periodic(apic)) {
> &gt;            advance_periodic_target_expiration(apic);
> &gt; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> &gt; index ce19b0e..bb5c4f1 100644
> &gt; --- a/arch/x86/kvm/vmx/vmx.c
> &gt; +++ b/arch/x86/kvm/vmx/vmx.c
> &gt; @@ -5994,7 +5994,8 @@ static int vmx_handle_exit(struct kvm_vcpu *vc=
pu, fastpath_t exit_fastpath)
> &gt;    if (exit_fastpath =3D=3D EXIT_FASTPATH_SKIP_EMUL_INS) {
> &gt;            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