From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B898C433EF for ; Thu, 21 Oct 2021 17:13:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1AB9B613A0 for ; Thu, 21 Oct 2021 17:13:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231701AbhJURPj (ORCPT ); Thu, 21 Oct 2021 13:15:39 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:27725 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229567AbhJURPh (ORCPT ); Thu, 21 Oct 2021 13:15:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634836401; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yllLqA21HI7HiQyi9iSL8DIj3iRFzAP86+C0IGx3f2Q=; b=YQnvIeUEoZ7uYMrqB5KuXBI4fBUQFflyVeot0aTJ3/Ksp2Gf8PbjZ9hNpBqh9Xbg9JTDXR JrgAEtLWoVZyp8KST7ZOwZlVcs/8jBbmbpYMgBY7o2BtO5BQkokOZo44rJr35/CamvHmeC HFKopSGMz5ptpT2smzZerXJX55eCwjU= Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-448-LZNayUnpMBewlAQ4UzDMOA-1; Thu, 21 Oct 2021 13:13:19 -0400 X-MC-Unique: LZNayUnpMBewlAQ4UzDMOA-1 Received: by mail-ed1-f70.google.com with SMTP id i7-20020a50d747000000b003db0225d219so1107553edj.0 for ; Thu, 21 Oct 2021 10:13:19 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=yllLqA21HI7HiQyi9iSL8DIj3iRFzAP86+C0IGx3f2Q=; b=21dQcuEW32jTSS0Let3X189G2fQAOqp7VTKBKcfmIqR70ZglbstreJzsN4UzjkPuxh TWW273c9kPKWq1suw2taaC3IIjT//udY0ZW+SYRuqEff36MJrj3lkEqZQvC6SGZjquNZ OWsrQQ50G99W5sWAw0kB1AsWkYv4jc+zYzGj8LqoLoNXcJNItwAHN3ChVAyhkEGerZYh JfJhazJ/76bw2brrX4uG1tjIszbmQc+1c5U/P1XVkWwFZqHsG2q1O/A02UenoLtdGPoQ j/D6bhRE5gxSAP8uT/n2ch+WWLJGS98BhseFJPF/YOOdk4/MXEgbg5b8Vi6TxwzPHyU9 EHcA== X-Gm-Message-State: AOAM533DM1XQcmnHDZlwUPg3vB8/p4D2k7pcg8qfQ/gVgJ128Re0IeKE iI2MwxZWZH8Jn7Z3vWo8nimyd0opAOaHcmfPQaqXRLCEYfxH/yE4uPyH2ghqEN6G9xKxN8uFPjM fPOjhfNf8Z0cqdfeH1DVYPZMd X-Received: by 2002:a17:907:334f:: with SMTP id yr15mr9116752ejb.8.1634836398565; Thu, 21 Oct 2021 10:13:18 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxWPR3wonWHNOs3y8vT+gjDmRUS38u9j+ZkN9PdXFXL5BIktKx51I1NPNokMxaEShcmMMwx3Q== X-Received: by 2002:a17:907:334f:: with SMTP id yr15mr9116725ejb.8.1634836398392; Thu, 21 Oct 2021 10:13:18 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:63a7:c72e:ea0e:6045? ([2001:b07:6468:f312:63a7:c72e:ea0e:6045]) by smtp.gmail.com with ESMTPSA id y22sm3465397edc.76.2021.10.21.10.13.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Oct 2021 10:13:17 -0700 (PDT) Message-ID: <945500f6-27e1-ed81-2b7d-c709cb1d4b33@redhat.com> Date: Thu, 21 Oct 2021 19:13:02 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH 1/4] KVM: X86: Fix tlb flush for tdp in kvm_invalidate_pcid() Content-Language: en-US To: Sean Christopherson , Lai Jiangshan Cc: Lai Jiangshan , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" References: <20211019110154.4091-1-jiangshanlai@gmail.com> <20211019110154.4091-2-jiangshanlai@gmail.com> <55abc519-b528-ddaa-120d-8d157b520623@linux.alibaba.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/10/21 16:52, Sean Christopherson wrote: >> I think the EPT violation happens*after* the cr3 write. So the instruction to be >> emulated is not "cr3 write". The emulation will queue fault into guest though, >> recursive EPT violation happens since the cr3 exceeds maxphyaddr limit. > Doh, you're correct. I think my mind wandered into thinking about what would > happen with PDPTRs and forgot to get back to normal MOV CR3. > > So yeah, the only way to correctly handle this would be to intercept CR3 loads. > I'm guessing that would have a noticeable impact on guest performance. Ouch... yeah, allow_smaller_maxphyaddr already has bad performance, but intercepting CR3 loads would be another kind of slow. Paolo > Paolo, I'll leave this one for you to decide, we have pretty much written off > allow_smaller_maxphyaddr:-)