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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CBE2C433EF for ; Fri, 7 Jan 2022 09:02:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346321AbiAGJCz (ORCPT ); Fri, 7 Jan 2022 04:02:55 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:39180 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236447AbiAGJCx (ORCPT ); Fri, 7 Jan 2022 04:02:53 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641546173; 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: in-reply-to:in-reply-to:references:references; bh=CJchP5kOngEUoTXC4a4FHodWajBGnUqSRJ+6FN2eEDs=; b=S5a7WvbxjR2nFOMopatoPuxdO+FL/gI/dk+n0qAcTF/w3CL86xD6JBHogLnIKXCyJehHTA UOEsffVFazgkbl+cmsRlmYP7LAhGAwSlFIgRwfmD5REqgfkdozlE5lKxLSmQno9Sp/G66Q 882ysD8iJjVSmCkvm1P7xj67YJY3vho= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-402-qTWjSXsXPI2N_r5u5P17Jg-1; Fri, 07 Jan 2022 04:02:51 -0500 X-MC-Unique: qTWjSXsXPI2N_r5u5P17Jg-1 Received: by mail-wm1-f72.google.com with SMTP id b9-20020a7bc249000000b00347c5699809so311179wmj.1 for ; Fri, 07 Jan 2022 01:02:51 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=CJchP5kOngEUoTXC4a4FHodWajBGnUqSRJ+6FN2eEDs=; b=kLLutbGt95N/0EqAcpHoWEvp+jI6uN2SK9ZKaP2v7FtK+8ndknCwFBJShAptUwryd+ 7MJUBtddzL2vcWxy7jAE8FZuinwXEbaxHHMI6jTE72gAB8zRQtXBjPg2sphnnxzIb6zb POOYo1STnpsFbOk6BHyETBZD7qggOH5uzIWC55jJtOIzi0J+E6GClWEaWpyZLXaC1CUN TZOCAvvrLmmpf/0uXF4/zmdbsS5iNO46Klg/0jpkJEK4jOxrEWbSwCteViC0WCneEyDz fmUgKy09e5+D7XQ4TL8K6K0BEcgX8c6740adgIgWjk2iHIhpkPie3JWyYAcxQ4++Hwt4 CAaw== X-Gm-Message-State: AOAM530nGbQalxmwPDV0gBRPAvcxPkFev6VzxyjrQ+ZvmPMCWu82rIo/ WxSWHEmluH4oyASHpLLl3Uow+gB5qDkB6BhvEmcw3v/KAczJPcXIUaLqR/V8GEKB6qbAaJxBAAB byd2Seow9sA17eiXWEGwi7Q/Xny707wyEJJNjSG9eQGI5J5tqmX/zWU01iEMV1rz7l2+TH2mXDj GM X-Received: by 2002:a05:6000:18af:: with SMTP id b15mr54674608wri.616.1641546170662; Fri, 07 Jan 2022 01:02:50 -0800 (PST) X-Google-Smtp-Source: ABdhPJyUgmSz+l/wRVwxeLTLElb+dNEm/Bi1KmSXD60E+b+hiSO3aMTKaLSf5ws/BZMiISGTJPusOQ== X-Received: by 2002:a05:6000:18af:: with SMTP id b15mr54674587wri.616.1641546170411; Fri, 07 Jan 2022 01:02:50 -0800 (PST) Received: from fedora (nat-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id y11sm4159245wrp.86.2022.01.07.01.02.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Jan 2022 01:02:49 -0800 (PST) From: Vitaly Kuznetsov To: Paolo Bonzini , Igor Mammedov Cc: kvm@vger.kernel.org, Sean Christopherson , Wanpeng Li , Jim Mattson , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] KVM: x86: Forbid KVM_SET_CPUID{,2} after KVM_RUN In-Reply-To: <87o84qpk7d.fsf@redhat.com> References: <20211122175818.608220-1-vkuznets@redhat.com> <20211122175818.608220-3-vkuznets@redhat.com> <16368a89-99ea-e52c-47b6-bd006933ec1f@redhat.com> <20211227183253.45a03ca2@redhat.com> <61325b2b-dc93-5db2-2d0a-dd0900d947f2@redhat.com> <87mtkdqm7m.fsf@redhat.com> <20220103104057.4dcf7948@redhat.com> <875yr1q8oa.fsf@redhat.com> <87o84qpk7d.fsf@redhat.com> Date: Fri, 07 Jan 2022 10:02:49 +0100 Message-ID: <877dbbq5om.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Vitaly Kuznetsov writes: > Paolo Bonzini writes: > >> On 1/3/22 13:56, Vitaly Kuznetsov wrote: >>> 'allowlist' of things which can change (and put >>> *APICids there) and only fail KVM_SET_CPUID{,2} when we see something >>> else changing. >> >> We could also go the other way and only deny changes that result in >> changed CPU caps. That should be easier to implement since we have >> already a mapping from CPU capability words to CPUID leaves and registers. >> > > Good idea, I'll look into it (if noone beats me to it). (just getting to it) On the other hand, e.g. MAXPHYADDR (CPUID 0x80000008.EAX) is not a CPU cap but it's one of the main reasons why we want to forbid KVM_SET_CPUID{,2} after KVM_RUN in the first place. I'm also not sure about allowing PV feature bits changes (KVM, Hyper-V, Xen) and I don't think there's a need for that. I'm again leaning towards an allowlist and currently I see only two candidates: CPUID.01H.EBX bits 31:24 (initial LAPIC id) CPUID.0BH.EDX (x2APIC id) Anything else I'm missing? -- Vitaly