linux-kernel - Re: [PATCH 2/2] KVM: X86: Implement PV send IPI support

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Message-ID: <CANRm+CwK2Wza0P236mcMaMDEMbHR+tyFhOZEJtiUs5vtPLGkzQ@mail.gmail.com>
Date:   Sat, 30 Jun 2018 18:05:33 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Radim Krcmar <rkrcmar@...hat.com>
Subject: Re: [PATCH 2/2] KVM: X86: Implement PV send IPI support

On Fri, 29 Jun 2018 at 18:49, Paolo Bonzini <pbonzini@...hat.com> wrote:
>
> On 29/06/2018 12:09, Vitaly Kuznetsov wrote:
> >> +KVM_FEATURE_PV_SEND_IPI            ||    11 || guest checks this feature bit
> >> +                                   ||       || before enabling paravirtualized
> >> +                                   ||       || send IPIs.
> > In case we decide to apply this as-is we'll likely need a new feature
> > for PV IPI with > 64 vCPUs (or how else would the guest know if the host
> > is capable or not?)
> >
>
> Yes, it makes sense.  Perhaps we can do one of the following, or both:
>
> 1) add an argument for a "base vCPU id", so that you can use the
> hypercall to send the IPI to CPUs 64..127, 128..191 etc.
>
> 2) have two bitmask arguments so that one hypercall handles 128 vCPUs.
>
> to remove or limit the need for the more generic hypercall.

Have already done 2) in v2, will send out later.

Regards,
Wanpeng Li