From nobody Mon Sep 29 22:37:12 2025 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 285BCC25B08 for ; Mon, 15 Aug 2022 21:53:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347603AbiHOVxW (ORCPT ); Mon, 15 Aug 2022 17:53:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349987AbiHOVt3 (ORCPT ); Mon, 15 Aug 2022 17:49:29 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2FE37BD14D; Mon, 15 Aug 2022 12:32:12 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 012C8B81128; Mon, 15 Aug 2022 19:32:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C72EC433C1; Mon, 15 Aug 2022 19:32:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660591929; bh=dq9WWjAYZEhXKKCWmOnvVPXflF8GkTuFqLiM/zsxIcE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lKzWzkJyd8KE7wDaFO2c2whRZdWPYHju6LzFlOOZPN7Nz704uhjnRc1cmuDqDQGKn tiMsI4LEiSFnim7RV4VG7BzRYSkYMTgtwknPJ/egx8HfT3WdASjEqwI30bKA9UG6te DgYrPZZMzFU4ttK+nE5CUJ+716pHpL2GEMj8jVLU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Paolo Bonzini Subject: [PATCH 5.19 0032/1157] KVM: x86: Split kvm_is_valid_cr4() and export only the non-vendor bits Date: Mon, 15 Aug 2022 19:49:48 +0200 Message-Id: <20220815180440.717962967@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180439.416659447@linuxfoundation.org> References: <20220815180439.416659447@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Sean Christopherson commit c33f6f2228fe8517e38941a508e9f905f99ecba9 upstream. Split the common x86 parts of kvm_is_valid_cr4(), i.e. the reserved bits checks, into a separate helper, __kvm_is_valid_cr4(), and export only the inner helper to vendor code in order to prevent nested VMX from calling back into vmx_is_valid_cr4() via kvm_is_valid_cr4(). On SVM, this is a nop as SVM doesn't place any additional restrictions on CR4. On VMX, this is also currently a nop, but only because nested VMX is missing checks on reserved CR4 bits for nested VM-Enter. That bug will be fixed in a future patch, and could simply use kvm_is_valid_cr4() as-is, but nVMX has _another_ bug where VMXON emulation doesn't enforce VMX's restrictions on CR0/CR4. The cleanest and most intuitive way to fix the VMXON bug is to use nested_host_cr{0,4}_valid(). If the CR4 variant routes through kvm_is_valid_cr4(), using nested_host_cr4_valid() won't do the right thing for the VMXON case as vmx_is_valid_cr4() enforces VMX's restrictions if and only if the vCPU is post-VMXON. Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-Id: <20220607213604.3346000-2-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/svm/nested.c | 3 ++- arch/x86/kvm/vmx/vmx.c | 4 ++-- arch/x86/kvm/x86.c | 12 +++++++++--- arch/x86/kvm/x86.h | 2 +- 4 files changed, 14 insertions(+), 7 deletions(-) --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -320,7 +320,8 @@ static bool __nested_vmcb_check_save(str return false; } =20 - if (CC(!kvm_is_valid_cr4(vcpu, save->cr4))) + /* Note, SVM doesn't have any additional restrictions on CR4. */ + if (CC(!__kvm_is_valid_cr4(vcpu, save->cr4))) return false; =20 if (CC(!kvm_valid_efer(vcpu, save->efer))) --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -3230,8 +3230,8 @@ static bool vmx_is_valid_cr4(struct kvm_ { /* * We operate under the default treatment of SMM, so VMX cannot be - * enabled under SMM. Note, whether or not VMXE is allowed at all is - * handled by kvm_is_valid_cr4(). + * enabled under SMM. Note, whether or not VMXE is allowed at all, + * i.e. is a reserved bit, is handled by common x86 code. */ if ((cr4 & X86_CR4_VMXE) && is_smm(vcpu)) return false; --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1094,7 +1094,7 @@ int kvm_emulate_xsetbv(struct kvm_vcpu * } EXPORT_SYMBOL_GPL(kvm_emulate_xsetbv); =20 -bool kvm_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) +bool __kvm_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) { if (cr4 & cr4_reserved_bits) return false; @@ -1102,9 +1102,15 @@ bool kvm_is_valid_cr4(struct kvm_vcpu *v if (cr4 & vcpu->arch.cr4_guest_rsvd_bits) return false; =20 - return static_call(kvm_x86_is_valid_cr4)(vcpu, cr4); + return true; +} +EXPORT_SYMBOL_GPL(__kvm_is_valid_cr4); + +static bool kvm_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) +{ + return __kvm_is_valid_cr4(vcpu, cr4) && + static_call(kvm_x86_is_valid_cr4)(vcpu, cr4); } -EXPORT_SYMBOL_GPL(kvm_is_valid_cr4); =20 void kvm_post_set_cr4(struct kvm_vcpu *vcpu, unsigned long old_cr4, unsign= ed long cr4) { --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -407,7 +407,7 @@ static inline void kvm_machine_check(voi void kvm_load_guest_xsave_state(struct kvm_vcpu *vcpu); void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu); int kvm_spec_ctrl_test_value(u64 value); -bool kvm_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4); +bool __kvm_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4); int kvm_handle_memory_failure(struct kvm_vcpu *vcpu, int r, struct x86_exception *e); int kvm_handle_invpcid(struct kvm_vcpu *vcpu, unsigned long type, gva_t gv= a);