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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 C3444C43603 for ; Wed, 11 Dec 2019 01:53:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9EC6C2073B for ; Wed, 11 Dec 2019 01:53:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727184AbfLKBxE (ORCPT ); Tue, 10 Dec 2019 20:53:04 -0500 Received: from mga06.intel.com ([134.134.136.31]:8970 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726062AbfLKBxE (ORCPT ); Tue, 10 Dec 2019 20:53:04 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Dec 2019 17:53:03 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,301,1571727600"; d="scan'208";a="203392706" Received: from unknown (HELO localhost) ([10.239.159.128]) by orsmga007.jf.intel.com with ESMTP; 10 Dec 2019 17:53:01 -0800 Date: Wed, 11 Dec 2019 09:54:23 +0800 From: Yang Weijiang To: Sean Christopherson Cc: Yang Weijiang , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, jmattson@google.com, yu.c.zhang@linux.intel.com, yu-cheng.yu@intel.com Subject: Re: [PATCH v8 4/7] KVM: VMX: Load CET states on vmentry/vmexit Message-ID: <20191211015423.GC12845@local-michael-cet-test> References: <20191101085222.27997-1-weijiang.yang@intel.com> <20191101085222.27997-5-weijiang.yang@intel.com> <20191210212305.GM15758@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191210212305.GM15758@linux.intel.com> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 10, 2019 at 01:23:05PM -0800, Sean Christopherson wrote: > On Fri, Nov 01, 2019 at 04:52:19PM +0800, Yang Weijiang wrote: > > @@ -2834,6 +2837,9 @@ void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) > > struct vcpu_vmx *vmx = to_vmx(vcpu); > > unsigned long hw_cr0; > > > > + if (!(cr0 & X86_CR0_WP) && kvm_read_cr4_bits(vcpu, X86_CR4_CET)) > > + cr0 |= X86_CR0_WP; > > Huh? What's the interaction between CR4.CET and CR0.WP? If there really > is some non-standard interaction then it needs to be documented in at least > the changelog and probably with a comment as well. > The processor does not allow CR4.CET to be set if CR0.WP = 0 (similarly, it does not allow CR0.WP to be cleared while CR4.CET = 1). > > + > > hw_cr0 = (cr0 & ~KVM_VM_CR0_ALWAYS_OFF); > > if (enable_unrestricted_guest) > > hw_cr0 |= KVM_VM_CR0_ALWAYS_ON_UNRESTRICTED_GUEST; > > @@ -2936,6 +2942,22 @@ static bool guest_cet_allowed(struct kvm_vcpu *vcpu, u32 feature, u32 mode) > > return false; > > } > > > > +bool is_cet_bit_allowed(struct kvm_vcpu *vcpu) > > +{ > > + unsigned long cr0; > > + bool cet_allowed; > > + > > + cr0 = kvm_read_cr0(vcpu); > > + cet_allowed = guest_cet_allowed(vcpu, X86_FEATURE_SHSTK, > > + XFEATURE_MASK_CET_USER) || > > + guest_cet_allowed(vcpu, X86_FEATURE_IBT, > > + XFEATURE_MASK_CET_USER); > > + if ((cr0 & X86_CR0_WP) && cet_allowed) > > + return true; > > So, attempting to set CR4.CET if CR0.WP=0 takes a #GP? But attempting > to clear CR0.WP if CR4.CET=1 is ignored? > Per above words in spec., inject #GP to guest in either case? > > + > > + return false; > > +} > > + > > int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) > > { > > struct vcpu_vmx *vmx = to_vmx(vcpu); > > @@ -2976,6 +2998,9 @@ int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) > > return 1; > > } > > > > + if ((cr4 & X86_CR4_CET) && !is_cet_bit_allowed(vcpu)) > > + return 1; > > + > > if (vmx->nested.vmxon && !nested_cr4_valid(vcpu, cr4)) > > return 1; > > > > @@ -3839,6 +3864,12 @@ void vmx_set_constant_host_state(struct vcpu_vmx *vmx) > > > > if (cpu_has_load_ia32_efer()) > > vmcs_write64(HOST_IA32_EFER, host_efer); > > + > > + if (cpu_has_load_host_cet_states_ctrl()) { > > + vmcs_writel(HOST_S_CET, 0); > > + vmcs_writel(HOST_INTR_SSP_TABLE, 0); > > + vmcs_writel(HOST_SSP, 0); > > + } > > } > > > > void set_cr4_guest_host_mask(struct vcpu_vmx *vmx) > > @@ -6436,6 +6467,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) > > { > > struct vcpu_vmx *vmx = to_vmx(vcpu); > > unsigned long cr3, cr4; > > + bool cet_allowed; > > > > /* Record the guest's net vcpu time for enforced NMI injections. */ > > if (unlikely(!enable_vnmi && > > @@ -6466,6 +6498,25 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) > > vmx->loaded_vmcs->host_state.cr3 = cr3; > > } > > > > + /* To be aligned with kernel code, only user mode is supported now. */ > > + cet_allowed = guest_cet_allowed(vcpu, X86_FEATURE_SHSTK, > > + XFEATURE_MASK_CET_USER) || > > + guest_cet_allowed(vcpu, X86_FEATURE_IBT, > > + XFEATURE_MASK_CET_USER); > > + if (cpu_has_load_guest_cet_states_ctrl() && cet_allowed) > > + vmcs_set_bits(VM_ENTRY_CONTROLS, > > + VM_ENTRY_LOAD_GUEST_CET_STATE); > > + else > > + vmcs_clear_bits(VM_ENTRY_CONTROLS, > > + VM_ENTRY_LOAD_GUEST_CET_STATE); > > + > > + if (cpu_has_load_host_cet_states_ctrl() && cet_allowed) > > + vmcs_set_bits(VM_EXIT_CONTROLS, > > + VM_EXIT_LOAD_HOST_CET_STATE); > > + else > > + vmcs_clear_bits(VM_EXIT_CONTROLS, > > + VM_EXIT_LOAD_HOST_CET_STATE); > > + > > cr4 = cr4_read_shadow(); > > if (unlikely(cr4 != vmx->loaded_vmcs->host_state.cr4)) { > > vmcs_writel(HOST_CR4, cr4); > > -- > > 2.17.2 > >