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Message-ID: <80ddc8a2-41c6-4e12-62f9-7acd51cabdb7@redhat.com>
Date:   Tue, 10 May 2022 16:18:26 +0200
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Subject: Re: [PATCH] KVM: LAPIC: Narrow down the timer fastpath to tscdeadline
 timer
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To:     Sean Christopherson <seanjc@google.com>,
        Wanpeng Li <kernellwp@gmail.com>
Cc:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>
References: <1651830457-11284-1-git-send-email-wanpengli@tencent.com>
 <YnpzetR/B3nXVJxu@google.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
In-Reply-To: <YnpzetR/B3nXVJxu@google.com>
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On 5/10/22 16:15, Sean Christopherson wrote:
>>   
>> -static fastpath_t handle_fastpath_preemption_timer(struct kvm_vcpu *vcpu)
>> +static bool __handle_preemption_timer(struct kvm_vcpu *vcpu)
>>   {
>>   	struct vcpu_vmx *vmx = to_vmx(vcpu);
>>   
>>   	if (!vmx->req_immediate_exit &&
>>   	    !unlikely(vmx->loaded_vmcs->hv_timer_soft_disabled)) {
>>   		kvm_lapic_expired_hv_timer(vcpu);
>> -		return EXIT_FASTPATH_REENTER_GUEST;
>> +		return true;
>>   	}
>>   
>> +	return false;
> It's a bit odd for the non-fastpath case, but I'd prefer to return fastpath_t
> instead of a bool from the inner helper, e.g.
> 

Yeah, enum > bool almost always (or negative errno).  But I also agree 
that using the fast path for periodic or oneshot timers is not 
inherently a bad idea.

Paolo