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From: Wanpeng Li <kernellwp@gmail.com>
To: Liran Alon <liran.alon@oracle.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>
Subject: Re: [PATCH v2 2/3] KVM: X86: Implement PV sched yield hypercall
Date: Thu, 30 May 2019 09:09:52 +0800	[thread overview]
Message-ID: <CANRm+Cx4egTwvbwwrS0Mi23QmesFDY+DkBAgVsC67o4ea3tYTg@mail.gmail.com> (raw)
In-Reply-To: <D119BC9B-3097-4453-BC17-5AE532EDB995@oracle.com>

On Wed, 29 May 2019 at 20:28, Liran Alon <liran.alon@oracle.com> wrote:
>
>
>
> > On 28 May 2019, at 3:53, Wanpeng Li <kernellwp@gmail.com> wrote:
> >
> > From: Wanpeng Li <wanpengli@tencent.com>
> >
> > The target vCPUs are in runnable state after vcpu_kick and suitable
> > as a yield target. This patch implements the sched yield hypercall.
> >
> > 17% performace increase of ebizzy benchmark can be observed in an
> > over-subscribe environment. (w/ kvm-pv-tlb disabled, testing TLB flush
> > call-function IPI-many since call-function is not easy to be trigged
> > by userspace workload).
> >
> > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > Cc: Radim Krčmář <rkrcmar@redhat.com>
> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> > ---
> > arch/x86/kvm/x86.c | 24 ++++++++++++++++++++++++
> > 1 file changed, 24 insertions(+)
> >
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index e7e57de..2ceef51 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -7172,6 +7172,26 @@ void kvm_vcpu_deactivate_apicv(struct kvm_vcpu *vcpu)
> >       kvm_x86_ops->refresh_apicv_exec_ctrl(vcpu);
> > }
> >
> > +void kvm_sched_yield(struct kvm *kvm, u64 dest_id)
> > +{
> > +     struct kvm_vcpu *target;
> > +     struct kvm_apic_map *map;
> > +
> > +     rcu_read_lock();
> > +     map = rcu_dereference(kvm->arch.apic_map);
> > +
> > +     if (unlikely(!map))
> > +             goto out;
> > +
>
> We should have a bounds-check here on “dest_id”.

Yeah, fix it in v3.

Regards,
Wanpeng Li

  reply	other threads:[~2019-05-30  1:10 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-28  0:53 [PATCH v2 0/3] KVM: Yield to IPI target if necessary Wanpeng Li
2019-05-28  0:53 ` [PATCH v2 1/3] KVM: X86: Implement PV sched yield in linux guest Wanpeng Li
2019-05-28  0:53 ` [PATCH v2 2/3] KVM: X86: Implement PV sched yield hypercall Wanpeng Li
2019-05-28  2:15   ` [PATCH RESEND v2] " Wanpeng Li
2019-05-28  6:08     ` kbuild test robot
2019-05-28  6:14       ` Wanpeng Li
2019-05-28  7:23     ` kbuild test robot
2019-05-28  7:50   ` [PATCH RESEND v2 0/3] KVM: Yield to IPI target if necessary Wanpeng Li
2019-05-28  7:50     ` [PATCH RESEND v2 1/3] KVM: X86: Implement PV sched yield in linux guest Wanpeng Li
2019-05-28  7:50     ` [PATCH RESEND v2 2/3] KVM: X86: Implement PV sched yield hypercall Wanpeng Li
2019-05-28  7:50     ` [PATCH RESEND v2 3/3] KVM: X86: Expose PV_SCHED_YIELD CPUID feature bit to guest Wanpeng Li
2019-05-28  9:11   ` [PATCH v2 2/3] KVM: X86: Implement PV sched yield hypercall Christian Borntraeger
2019-05-28  9:57     ` Wanpeng Li
2019-05-29 12:28   ` Liran Alon
2019-05-30  1:09     ` Wanpeng Li [this message]
2019-05-28  0:53 ` [PATCH v2 3/3] KVM: X86: Expose PV_SCHED_YIELD CPUID feature bit to guest Wanpeng Li

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