linux-kernel - Re: [PATCH RESEND 2/3] KVM: Add paravirt remote TLB flush

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Message-ID: <CANRm+Cyy1stZFpKuan+ZJV4nH-X+tM67Z+UF9ivyu6fgOA30Yg@mail.gmail.com>
Date:   Thu, 9 Nov 2017 19:08:52 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kvm <kvm@...r.kernel.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>,
        Eduardo Valentin <eduval@...zon.com>
Subject: Re: [PATCH RESEND 2/3] KVM: Add paravirt remote TLB flush

2017-11-09 19:02 GMT+08:00 Paolo Bonzini <pbonzini@...hat.com>:
> On 09/11/2017 12:01, Wanpeng Li wrote:
>> 2017-11-09 18:48 GMT+08:00 Paolo Bonzini <pbonzini@...hat.com>:
>>> On 09/11/2017 03:02, Wanpeng Li wrote:
>>>> @@ -484,6 +511,8 @@ void __init kvm_guest_init(void)
>>>>               pv_time_ops.steal_clock = kvm_steal_clock;
>>>>       }
>>>>
>>>> +     pv_mmu_ops.flush_tlb_others = kvm_flush_tlb_others;
>>>
>>> This needs to be keyed on a new CPUID feature bit.  Eduardo is also
>>
>> Will do.
>>
>>> adding a new "PV_DEDICATED" hint and you might disable PV TLB flush when
>>> PV_DEDICATED is set.
>>
>> Why disable PV TLB flush for PV_DEDICATED(qspinlock)?
>
> PV_DEDICATED says pretty much that it is very unlikely to have a
> preempted vCPU.  Therefore, the cpumask loop is unnecessary.

Thanks for pointing out this. :)

Regards,
Wanpeng Li