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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id ho32sm832997ejc.82.2021.05.27.04.39.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 27 May 2021 04:39:22 -0700 (PDT) Subject: Re: [PATCH v2 3/5] KVM: x86: Use common 'enable_apicv' variable for both APICv and AVIC To: Maxim Levitsky , Sean Christopherson Cc: Vitaly Kuznetsov , kvm@vger.kernel.org, Wanpeng Li , Jim Mattson , Kechen Lu , linux-kernel@vger.kernel.org References: <20210518144339.1987982-1-vkuznets@redhat.com> <20210518144339.1987982-4-vkuznets@redhat.com> <1b9a654596f755ee5ef42ce11136ed2bbb3995a0.camel@redhat.com> <8e2570c580baf6d4d650ebc28b98a5ed76cb4f9b.camel@redhat.com> From: Paolo Bonzini Message-ID: <5d8b607b-f280-fd3e-c147-94111468d5a1@redhat.com> Date: Thu, 27 May 2021 13:39:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <8e2570c580baf6d4d650ebc28b98a5ed76cb4f9b.camel@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/05/21 17:52, Maxim Levitsky wrote: >> I don't love the intermediate "avic" either, but there isn't a good alternative. >> Forcing VMX to also use an intermediate doesn't make much sense, we'd be penalizing >> ourselves in the form of unnecessary complexity just because AVIC needs to be >> disabled by default for reasons KVM can't fix. > This is also something we should eventually reconsider. > These days, the AVIC works quite well and disables itself when needed. > When do you think it will be the time to enable it by default? We can probably enable it, but most guests won't use it because of x2apic. Paolo