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 X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1925C433ED for ; Sat, 24 Apr 2021 00:51:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C86E36128A for ; Sat, 24 Apr 2021 00:51:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244389AbhDXAwD (ORCPT ); Fri, 23 Apr 2021 20:52:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36828 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244218AbhDXAt5 (ORCPT ); Fri, 23 Apr 2021 20:49:57 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36736C06136C for ; Fri, 23 Apr 2021 17:47:49 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id a7-20020a5b00070000b02904ed415d9d84so4616515ybp.0 for ; Fri, 23 Apr 2021 17:47:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=Ew2nV1C2QkTbVPUHEDeR3BqzkrHRV1hyqurcl8ylJqA=; b=Q/+euOX/jNPV0L+/HCLRbjP+tdZVMolhBrphGswflROesQAMX/mKt4/qDAZgSlzR6u XLqaFXtMPQG13Og4KpzQOqGfOt4eFgHbmxpoyFNhUt1FY419Q1HyUP1I6pkgZbwVGkx8 F7+vNX8lVz0LNFeRUDsTorj5bgM9Oh0wfBbZarrYnvSr+aMFoqAy+Fv5ekwizD8Ga6mI 0b1DxdCPi8isOCr2JUs7CGKsJlH/w2EiC9x2rwK2cZDuQROlHMP1IsNled/w5n02FID/ SZXlLqT8xZEhSs8OgQ+OMLMqJYW9AFT2RanZRsWG4zg87Vz803KVZACsX+kabnuJFFiX eoNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=Ew2nV1C2QkTbVPUHEDeR3BqzkrHRV1hyqurcl8ylJqA=; b=f63XeawqIW26KCixaDuIi3/4f9Uvo7WNohUtthAYQluFusjyIx8+l8/ZuTtXauWt3R q6R/lUJYWyKC2rdjTvXPb5b+/6bISG5kVk/DrdCQ8OEiogg0uq32YZc0PTJmLXnGKcKT h24/X109TnDteI2IYxMnm2mGMfbevapkpqYoXWidi3wx4yO0E4wC65AjCffS5RiDuAeY xBbU+UDT8zJ/7gY8rqEhdK6qHN5ZPWtnQLMDuYnPvKKDqR4t+QndZiVJ8fEFY3438WRV hZXPqmLa5q0xAc52fBmRcBOLd/1ZA/usvFOW7YtGqQVjB0h3gw9Qc7AIlEibcO2tO6w7 m1oQ== X-Gm-Message-State: AOAM530T5syM8E6SzuD1z3BX/UvNl2YQY4iJTufBJBSgJqTZ/dMutO5F RGUSQp3rDv1pJXvYROx1A+7qMjec1BM= X-Google-Smtp-Source: ABdhPJz4owlPeswNQ7Hsm2Ba7sazeB4/U3MZQetD/sxaZrXNUPfYQB6CwbIIvGWqfRuoL9tIsNKaUOIGiqY= X-Received: from seanjc798194.pdx.corp.google.com ([2620:15c:f:10:ad52:3246:e190:f070]) (user=seanjc job=sendgmr) by 2002:a5b:44e:: with SMTP id s14mr9583662ybp.11.1619225268482; Fri, 23 Apr 2021 17:47:48 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 23 Apr 2021 17:46:24 -0700 In-Reply-To: <20210424004645.3950558-1-seanjc@google.com> Message-Id: <20210424004645.3950558-23-seanjc@google.com> Mime-Version: 1.0 References: <20210424004645.3950558-1-seanjc@google.com> X-Mailer: git-send-email 2.31.1.498.g6c1eba8ee3d-goog Subject: [PATCH 22/43] KVM: VMX: Remove direct write to vcpu->arch.cr0 during vCPU RESET/INIT From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Remove a bogus write to vcpu->arch.cr0 that immediately precedes vmx_set_cr0() during vCPU RESET/INIT. For RESET, this is a nop since the "old" CR0 value is meaningless. But for INIT, if the vCPU is coming from paging enabled mode, crushing vcpu->arch.cr0 will cause the various is_paging() checks in vmx_set_cr0() to get false negatives. For the exit_lmode() case, the false negative is benign as vmx_set_efer() is called immediately after vmx_set_cr0(). For EPT without unrestricted guest, the false negative will cause KVM to unnecessarily run with CR3 load/store exiting. But again, this is benign, albeit sub-optimal. Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/vmx.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index d0050c140b4d..5795de909609 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4486,7 +4486,6 @@ static void init_vmcs(struct vcpu_vmx *vmx) static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) { struct vcpu_vmx *vmx = to_vmx(vcpu); - u64 cr0; if (!init_event) init_vmcs(vmx); @@ -4557,9 +4556,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu); - cr0 = X86_CR0_NW | X86_CR0_CD | X86_CR0_ET; - vmx->vcpu.arch.cr0 = cr0; - vmx_set_cr0(vcpu, cr0); /* enter rmode */ + vmx_set_cr0(vcpu, X86_CR0_NW | X86_CR0_CD | X86_CR0_ET); vmx_set_cr4(vcpu, 0); vmx_set_efer(vcpu, 0); -- 2.31.1.498.g6c1eba8ee3d-goog