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 77734C433EF for ; Thu, 13 Jan 2022 09:27:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232729AbiAMJ1g (ORCPT ); Thu, 13 Jan 2022 04:27:36 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:60202 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230094AbiAMJ1f (ORCPT ); Thu, 13 Jan 2022 04:27:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642066054; 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=9u4mM8xpzGhQTXqNOSpCIuqLOs+p1DjaP1wP5fvTV0U=; b=IGTl/4ydkniQ6wNVIR+8qXrh4DokGBwHBSjS/Z8O7IWEezsanFv/U42DXxbHDHdfqLJSbS 6jsH7jv+KV0POTu5D/aBgStNfZDfa4hqeZ28nG0nB6Yncu+C/PKrNcGKjl4KlEe9IreKn3 FspqY313LyvosI2DmIZx0LAfrPQ3pjk= Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-260-sCUn2xi-Msm3V8E4KL-4xw-1; Thu, 13 Jan 2022 04:27:33 -0500 X-MC-Unique: sCUn2xi-Msm3V8E4KL-4xw-1 Received: by mail-ed1-f72.google.com with SMTP id c8-20020a05640227c800b003fdc1684cdeso4826417ede.12 for ; Thu, 13 Jan 2022 01:27:33 -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=9u4mM8xpzGhQTXqNOSpCIuqLOs+p1DjaP1wP5fvTV0U=; b=G122pEgQOzbI0leehErVsflJTOwSXwL6tOxVXVC5tMloSEcm2PtjXPEm0sAEKhtqsB BaaKZbyAmBMIHQn4XLbq2pQBxjhMYoCqH88c52gk24Zh3qoCqXtpUbSk3FyRjv3mebkz nqT7qxX215rguI5OTgK7jzRCUM7l/XJffUTj6VoONcY0SfUhfcXGu/1blbK4KMS4J8tz 5LYV609lft/kLdhL3NlI31kL3LBaVCJpWDxKNSpqgEw6fX5StgynOWOaUq3i48TfWAER yHVLuvG5rLaaqYEg99na49SstI+9kQhlcT7pQI97xraBaDYM15p63iany+iWQ92+RX2V Lp+Q== X-Gm-Message-State: AOAM5335Vrxnf8UGG+IYB0/DvRVCsZ4W3QRGtD0K3Hh4DQNo+VNvDWlM ief2868AWxhi1y/53vSZ36vOaE3AvkGh7366o0uG/HHUUCr8jaFqVwAGeSuD9+6VvPvnJSh6/Op wY0K1FRM/m+fK X-Received: by 2002:a50:d74e:: with SMTP id i14mr3257719edj.243.1642066052534; Thu, 13 Jan 2022 01:27:32 -0800 (PST) X-Google-Smtp-Source: ABdhPJyxknbT0PRuA/sllWl1GxiPU1rPaJrzQ/P32/YPeYZnMkI87/uDO/WsTaCwyYZr8gCuLccFgA== X-Received: by 2002:a50:d74e:: with SMTP id i14mr3257708edj.243.1642066052360; Thu, 13 Jan 2022 01:27:32 -0800 (PST) Received: from fedora (nat-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id oz31sm671867ejc.35.2022.01.13.01.27.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Jan 2022 01:27:31 -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: <50136685-706e-fc6a-0a77-97e584e74f93@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> <877dbbq5om.fsf@redhat.com> <5505d731-cf87-9662-33f3-08844d92877c@redhat.com> <20220111090022.1125ffb5@redhat.com> <87fsptnjic.fsf@redhat.com> <50136685-706e-fc6a-0a77-97e584e74f93@redhat.com> Date: Thu, 13 Jan 2022 10:27:30 +0100 Message-ID: <87bl0gnfy5.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Paolo Bonzini writes: > On 1/12/22 14:58, Vitaly Kuznetsov wrote: >> - best = kvm_find_cpuid_entry(vcpu, 0xD, 1); >> + best = cpuid_entry2_find(entries, nent, 0xD, 1); >> if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) || >> cpuid_entry_has(best, X86_FEATURE_XSAVEC))) >> best->ebx = xstate_required_size(vcpu->arch.xcr0, true); >> >> - best = kvm_find_kvm_cpuid_features(vcpu); >> + best = __kvm_find_kvm_cpuid_features(vcpu, vcpu->arch.cpuid_entries, >> + vcpu->arch.cpuid_nent); >> if (kvm_hlt_in_guest(vcpu->kvm) && best && > > I think this should be __kvm_find_kvm_cpuid_features(vcpu, entries, nent). > Of course. >> >> + case 0x1: >> + /* Only initial LAPIC id is allowed to change */ >> + if (e->eax ^ best->eax || ((e->ebx ^ best->ebx) >> 24) || >> + e->ecx ^ best->ecx || e->edx ^ best->edx) >> + return -EINVAL; >> + break; > > This XOR is a bit weird. In addition the EBX test is checking the wrong > bits (it checks whether 31:24 change and ignores changes to 23:0). Indeed, however, I've tested CPU hotplug with QEMU trying different CPUs in random order and surprisingly othing blew up, feels like QEMU was smart enough to re-use the right fd) > > You can write just "(e->ebx & ~0xff000000u) != (best->ebx ~0xff000000u)". > >> >> + default: >> + if (e->eax ^ best->eax || e->ebx ^ best->ebx || >> + e->ecx ^ best->ecx || e->edx ^ best->edx) >> + return -EINVAL; > > This one even more so. Thanks for the early review, I'm going to prepare a selftest and send this out. -- Vitaly