linux-kernel - Re: [PATCH v5 4/4] KVM: async_pf: Let host know whether the guest support delivery async

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Date:   Tue, 27 Jun 2017 15:19:41 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH v5 4/4] KVM: async_pf: Let host know whether the guest
 support delivery async_pf as #PF vmexit



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);

Thanks,

Paolo