From patchwork Mon Aug 9 14:53:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emanuele Giuseppe Esposito X-Patchwork-Id: 12426729 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=-16.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 4C336C4338F for ; Mon, 9 Aug 2021 14:55:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 24D3860C41 for ; Mon, 9 Aug 2021 14:55:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235319AbhHIOzW (ORCPT ); Mon, 9 Aug 2021 10:55:22 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:51945 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235326AbhHIOzP (ORCPT ); Mon, 9 Aug 2021 10:55:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628520894; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dZYvnn5g98PxjXEQfMRGjEyYcFjOOPfx2qqowIkJGi8=; b=VIUZaDoRly7g165gX03ZLB6rm2QISNSGxhzZFi8w5eiTIkBeYBHj5G36SALuJ6Cqyms6+j f4EF6rTpkmvFgO+pPucY/35gQR+xPuQkIcLMMdYFdP/mdsqDzQVl8ZmljY+a9sQDMaMHL7 eTTQYc+wlVx0E5jmgzHCJDopQggrQy4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-451-vOyOKZFnNse-gxkCvwLgNA-1; Mon, 09 Aug 2021 10:54:50 -0400 X-MC-Unique: vOyOKZFnNse-gxkCvwLgNA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 789FB100A614; Mon, 9 Aug 2021 14:54:29 +0000 (UTC) Received: from localhost.localdomain (unknown [10.39.193.220]) by smtp.corp.redhat.com (Postfix) with ESMTP id C5F4B78AAF; Mon, 9 Aug 2021 14:54:24 +0000 (UTC) From: Emanuele Giuseppe Esposito To: kvm@vger.kernel.org Cc: Paolo Bonzini , Maxim Levitsky , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, Emanuele Giuseppe Esposito Subject: [PATCH 1/2] KVM: nSVM: move nested_vmcb_check_cr3_cr4 logic in nested_vmcb_valid_sregs Date: Mon, 9 Aug 2021 16:53:42 +0200 Message-Id: <20210809145343.97685-2-eesposit@redhat.com> In-Reply-To: <20210809145343.97685-1-eesposit@redhat.com> References: <20210809145343.97685-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org nested_vmcb_check_cr3_cr4 is not called by anyone else, and removing the call simplifies next patch Signed-off-by: Emanuele Giuseppe Esposito Reviewed-by: Maxim Levitsky --- arch/x86/kvm/svm/nested.c | 35 +++++++++++++---------------------- 1 file changed, 13 insertions(+), 22 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 5e13357da21e..0ac2d14add15 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -257,27 +257,6 @@ static bool nested_vmcb_check_controls(struct kvm_vcpu *vcpu, return true; } -static bool nested_vmcb_check_cr3_cr4(struct kvm_vcpu *vcpu, - struct vmcb_save_area *save) -{ - /* - * These checks are also performed by KVM_SET_SREGS, - * except that EFER.LMA is not checked by SVM against - * CR0.PG && EFER.LME. - */ - if ((save->efer & EFER_LME) && (save->cr0 & X86_CR0_PG)) { - if (CC(!(save->cr4 & X86_CR4_PAE)) || - CC(!(save->cr0 & X86_CR0_PE)) || - CC(kvm_vcpu_is_illegal_gpa(vcpu, save->cr3))) - return false; - } - - if (CC(!kvm_is_valid_cr4(vcpu, save->cr4))) - return false; - - return true; -} - /* Common checks that apply to both L1 and L2 state. */ static bool nested_vmcb_valid_sregs(struct kvm_vcpu *vcpu, struct vmcb_save_area *save) @@ -299,7 +278,19 @@ static bool nested_vmcb_valid_sregs(struct kvm_vcpu *vcpu, if (CC(!kvm_dr6_valid(save->dr6)) || CC(!kvm_dr7_valid(save->dr7))) return false; - if (!nested_vmcb_check_cr3_cr4(vcpu, save)) + /* + * These checks are also performed by KVM_SET_SREGS, + * except that EFER.LMA is not checked by SVM against + * CR0.PG && EFER.LME. + */ + if ((save->efer & EFER_LME) && (save->cr0 & X86_CR0_PG)) { + if (CC(!(save->cr4 & X86_CR4_PAE)) || + CC(!(save->cr0 & X86_CR0_PE)) || + CC(kvm_vcpu_is_illegal_gpa(vcpu, save->cr3))) + return false; + } + + if (CC(!kvm_is_valid_cr4(vcpu, save->cr4))) return false; if (CC(!kvm_valid_efer(vcpu, save->efer))) From patchwork Mon Aug 9 14:53:43 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emanuele Giuseppe Esposito X-Patchwork-Id: 12426731 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=-13.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, UNWANTED_LANGUAGE_BODY,URIBL_BLOCKED autolearn=ham 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 E2729C4320A for ; Mon, 9 Aug 2021 14:55:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C936361019 for ; 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Mon, 09 Aug 2021 10:54:56 -0400 X-MC-Unique: o35Qq__SN_WSsti7M_-SzA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AF44E100A96A; Mon, 9 Aug 2021 14:54:32 +0000 (UTC) Received: from localhost.localdomain (unknown [10.39.193.220]) by smtp.corp.redhat.com (Postfix) with ESMTP id 911F07A51F; Mon, 9 Aug 2021 14:54:29 +0000 (UTC) From: Emanuele Giuseppe Esposito To: kvm@vger.kernel.org Cc: Paolo Bonzini , Maxim Levitsky , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, Emanuele Giuseppe Esposito Subject: [PATCH 2/2] KVM: nSVM: temporarly save vmcb12's efer, cr0 and cr4 to avoid TOC/TOU races Date: Mon, 9 Aug 2021 16:53:43 +0200 Message-Id: <20210809145343.97685-3-eesposit@redhat.com> In-Reply-To: <20210809145343.97685-1-eesposit@redhat.com> References: <20210809145343.97685-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Move the checks done by nested_vmcb_valid_sregs and nested_vmcb_check_controls directly in enter_svm_guest_mode, and save the values of vmcb12's efer, cr0 and cr4 in local variable that are then passed to nested_vmcb02_prepare_save. This prevents from creating TOC/TOU races. This also avoids the need of force-setting EFER_SVME in nested_vmcb02_prepare_save. Signed-off-by: Emanuele Giuseppe Esposito --- arch/x86/kvm/svm/nested.c | 72 +++++++++++++++++++-------------------- 1 file changed, 36 insertions(+), 36 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 0ac2d14add15..04e9e947deb9 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -259,20 +259,14 @@ static bool nested_vmcb_check_controls(struct kvm_vcpu *vcpu, /* Common checks that apply to both L1 and L2 state. */ static bool nested_vmcb_valid_sregs(struct kvm_vcpu *vcpu, - struct vmcb_save_area *save) + struct vmcb_save_area *save, + u64 efer, u64 cr0, u64 cr4) { - /* - * FIXME: these should be done after copying the fields, - * to avoid TOC/TOU races. For these save area checks - * the possible damage is limited since kvm_set_cr0 and - * kvm_set_cr4 handle failure; EFER_SVME is an exception - * so it is force-set later in nested_prepare_vmcb_save. - */ - if (CC(!(save->efer & EFER_SVME))) + if (CC(!(efer & EFER_SVME))) return false; - if (CC((save->cr0 & X86_CR0_CD) == 0 && (save->cr0 & X86_CR0_NW)) || - CC(save->cr0 & ~0xffffffffULL)) + if (CC((cr0 & X86_CR0_CD) == 0 && (cr0 & X86_CR0_NW)) || + CC(cr0 & ~0xffffffffULL)) return false; if (CC(!kvm_dr6_valid(save->dr6)) || CC(!kvm_dr7_valid(save->dr7))) @@ -283,17 +277,16 @@ static bool nested_vmcb_valid_sregs(struct kvm_vcpu *vcpu, * except that EFER.LMA is not checked by SVM against * CR0.PG && EFER.LME. */ - if ((save->efer & EFER_LME) && (save->cr0 & X86_CR0_PG)) { - if (CC(!(save->cr4 & X86_CR4_PAE)) || - CC(!(save->cr0 & X86_CR0_PE)) || + if ((efer & EFER_LME) && (cr0 & X86_CR0_PG)) { + if (CC(!(cr4 & X86_CR4_PAE)) || CC(!(cr0 & X86_CR0_PE)) || CC(kvm_vcpu_is_illegal_gpa(vcpu, save->cr3))) return false; } - if (CC(!kvm_is_valid_cr4(vcpu, save->cr4))) + if (CC(!kvm_is_valid_cr4(vcpu, cr4))) return false; - if (CC(!kvm_valid_efer(vcpu, save->efer))) + if (CC(!kvm_valid_efer(vcpu, efer))) return false; return true; @@ -434,7 +427,9 @@ void nested_vmcb02_compute_g_pat(struct vcpu_svm *svm) svm->nested.vmcb02.ptr->save.g_pat = svm->vmcb01.ptr->save.g_pat; } -static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12) +static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, + struct vmcb *vmcb12, + u64 efer, u64 cr0, u64 cr4) { bool new_vmcb12 = false; @@ -463,15 +458,10 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12 kvm_set_rflags(&svm->vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED); - /* - * Force-set EFER_SVME even though it is checked earlier on the - * VMCB12, because the guest can flip the bit between the check - * and now. Clearing EFER_SVME would call svm_free_nested. - */ - svm_set_efer(&svm->vcpu, vmcb12->save.efer | EFER_SVME); + svm_set_efer(&svm->vcpu, efer); - svm_set_cr0(&svm->vcpu, vmcb12->save.cr0); - svm_set_cr4(&svm->vcpu, vmcb12->save.cr4); + svm_set_cr0(&svm->vcpu, cr0); + svm_set_cr4(&svm->vcpu, cr4); svm->vcpu.arch.cr2 = vmcb12->save.cr2; @@ -567,6 +557,7 @@ int enter_svm_guest_mode(struct kvm_vcpu *vcpu, u64 vmcb12_gpa, { struct vcpu_svm *svm = to_svm(vcpu); int ret; + u64 vmcb12_efer, vmcb12_cr0, vmcb12_cr4; trace_kvm_nested_vmrun(svm->vmcb->save.rip, vmcb12_gpa, vmcb12->save.rip, @@ -589,8 +580,25 @@ int enter_svm_guest_mode(struct kvm_vcpu *vcpu, u64 vmcb12_gpa, nested_svm_copy_common_state(svm->vmcb01.ptr, svm->nested.vmcb02.ptr); svm_switch_vmcb(svm, &svm->nested.vmcb02); + + /* Save vmcb12's EFER, CR0 and CR4 to avoid TOC/TOU races. */ + vmcb12_efer = vmcb12->save.efer; + vmcb12_cr0 = vmcb12->save.cr0; + vmcb12_cr4 = vmcb12->save.cr4; + + if (!nested_vmcb_valid_sregs(vcpu, &vmcb12->save, vmcb12_efer, + vmcb12_cr0, vmcb12_cr4) || + !nested_vmcb_check_controls(vcpu, &svm->nested.ctl)) { + vmcb12->control.exit_code = SVM_EXIT_ERR; + vmcb12->control.exit_code_hi = 0; + vmcb12->control.exit_info_1 = 0; + vmcb12->control.exit_info_2 = 0; + return 1; + } + nested_vmcb02_prepare_control(svm); - nested_vmcb02_prepare_save(svm, vmcb12); + nested_vmcb02_prepare_save(svm, vmcb12, vmcb12_efer, vmcb12_cr0, + vmcb12_cr4); ret = nested_svm_load_cr3(&svm->vcpu, vmcb12->save.cr3, nested_npt_enabled(svm), true); @@ -641,15 +649,6 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu) nested_load_control_from_vmcb12(svm, &vmcb12->control); - if (!nested_vmcb_valid_sregs(vcpu, &vmcb12->save) || - !nested_vmcb_check_controls(vcpu, &svm->nested.ctl)) { - vmcb12->control.exit_code = SVM_EXIT_ERR; - vmcb12->control.exit_code_hi = 0; - vmcb12->control.exit_info_1 = 0; - vmcb12->control.exit_info_2 = 0; - goto out; - } - /* * Since vmcb01 is not in use, we can use it to store some of the L1 * state. @@ -1336,7 +1335,8 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, if (!(save->cr0 & X86_CR0_PG) || !(save->cr0 & X86_CR0_PE) || (save->rflags & X86_EFLAGS_VM) || - !nested_vmcb_valid_sregs(vcpu, save)) + !nested_vmcb_valid_sregs(vcpu, save, save->efer, save->cr0, + save->cr4)) goto out_free; /*