linux-kernel - Re: [PATCH 1/2] KVM: X86: Implement PV IPI in linux guest

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Date:   Sat, 30 Jun 2018 18:04:12 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krcmar <rkrcmar@...hat.com>
Subject: Re: [PATCH 1/2] KVM: X86: Implement PV IPI in linux guest

On Fri, 29 Jun 2018 at 18:10, Vitaly Kuznetsov <vkuznets@...hat.com> wrote:
>
> Wanpeng Li <kernellwp@...il.com> writes:
>
> > From: Wanpeng Li <wanpengli@...cent.com>
> >
> > Implement PV IPIs in guest kernel.
> >
> > Cc: Paolo Bonzini <pbonzini@...hat.com>
> > Cc: Radim Krčmář <rkrcmar@...hat.com>
> > Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
> > Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> > ---
> >  arch/x86/include/uapi/asm/kvm_para.h |  1 +
> >  arch/x86/kernel/kvm.c                | 63 ++++++++++++++++++++++++++++++++++++
> >  2 files changed, 64 insertions(+)
> >
> > diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
> > index 0ede697..19980ec 100644
> > --- a/arch/x86/include/uapi/asm/kvm_para.h
> > +++ b/arch/x86/include/uapi/asm/kvm_para.h
> > @@ -28,6 +28,7 @@
> >  #define KVM_FEATURE_PV_UNHALT                7
> >  #define KVM_FEATURE_PV_TLB_FLUSH     9
> >  #define KVM_FEATURE_ASYNC_PF_VMEXIT  10
> > +#define KVM_FEATURE_PV_SEND_IPI      11
> >
> >  #define KVM_HINTS_REALTIME      0
> >
> > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> > index 5b2300b..b4f8dc3 100644
> > --- a/arch/x86/kernel/kvm.c
> > +++ b/arch/x86/kernel/kvm.c
> > @@ -454,6 +454,57 @@ static void __init sev_map_percpu_data(void)
> >  }
> >
> >  #ifdef CONFIG_SMP
> > +
> > +static void __send_ipi_mask(const struct cpumask *mask, int vector)
> > +{
> > +     unsigned long flags, ipi_bitmap = 0;
> > +     int cpu;
> > +
> > +     local_irq_save(flags);
> > +
> > +     for_each_cpu(cpu, mask)
> > +             __set_bit(per_cpu(x86_cpu_to_apicid, cpu), &ipi_bitmap);
>
> We need a protection against per_cpu(x86_cpu_to_apicid, cpu) > here.

Will do in v2.

Regards,
Wanpeng Li