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From: Wanpeng Li <kernellwp@gmail.com>
Date: Wed, 28 Jun 2017 06:49:28 +0800
Message-ID: <CANRm+Cz1r_9iyJySwA6Vq25UAya+wgWDCNbaJBqNarkjDFODGw@mail.gmail.com>
Subject: Re: [PATCH v5 4/4] KVM: async_pf: Let host know whether the guest
 support delivery async_pf as #PF vmexit
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        kvm <kvm@vger.kernel.org>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Wanpeng Li <wanpeng.li@hotmail.com>
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2017-06-27 21:19 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>
>
> On 27/06/2017 03:47, Wanpeng Li wrote:
>> -             wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED);
>> +             pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT | KVM_ASYNC_PF_ENABLED;
>> +             wrmsr_safe(MSR_KVM_ASYNC_PF_EN, pa & 0xffffffff, pa >> 32);
>>               __this_cpu_write(apf_reason.enabled, 1);
>
> Better:
>
>         pa |= KVM_ASYNC_PF_ENABLED;
>
>         /* Async page fault support for L1 hypervisor is optional.  */
>         if (wrmsr_safe(MSR_KVM_ASYNC_PF_EN,
>                        pa | KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT) < 0)
>                 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);

Good point. :)

Regards,
Wanpeng Li