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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 B4180C00454 for ; Tue, 10 Dec 2019 21:23:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 85ACD20836 for ; Tue, 10 Dec 2019 21:23:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729412AbfLJVXH (ORCPT ); Tue, 10 Dec 2019 16:23:07 -0500 Received: from mga01.intel.com ([192.55.52.88]:58948 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727640AbfLJVXH (ORCPT ); Tue, 10 Dec 2019 16:23:07 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Dec 2019 13:23:06 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,300,1571727600"; d="scan'208";a="264656217" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by FMSMGA003.fm.intel.com with ESMTP; 10 Dec 2019 13:23:06 -0800 Date: Tue, 10 Dec 2019 13:23:05 -0800 From: Sean Christopherson To: Yang Weijiang Cc: 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: <20191210212305.GM15758@linux.intel.com> References: <20191101085222.27997-1-weijiang.yang@intel.com> <20191101085222.27997-5-weijiang.yang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191101085222.27997-5-weijiang.yang@intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Nov 01, 2019 at 04:52:19PM +0800, Yang Weijiang wrote: > "Load {guest,host} CET state" bit controls whether guest/host > CET states will be loaded at VM entry/exit. Before doing that, > KVM needs to check if CET is both enabled on host and guest. > > Note: SHSTK and IBT features share one control MSR: > MSR_IA32_{U,S}_CET, which means it's difficult to hide > one feature from another in the case of SHSTK != IBT, > after discussed in community, it's agreed to allow Guest > control two features independently as it won't introduce > security hole. > > Co-developed-by: Zhang Yi Z > Signed-off-by: Zhang Yi Z > Signed-off-by: Yang Weijiang > --- ... > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index db03d9dc1297..e392e818e7eb 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -44,6 +44,7 @@ > #include > #include > #include > +#include > > #include "capabilities.h" > #include "cpuid.h" > @@ -2336,7 +2337,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf, > VM_EXIT_LOAD_IA32_EFER | > VM_EXIT_CLEAR_BNDCFGS | > VM_EXIT_PT_CONCEAL_PIP | > - VM_EXIT_CLEAR_IA32_RTIT_CTL; > + VM_EXIT_CLEAR_IA32_RTIT_CTL | > + VM_EXIT_LOAD_HOST_CET_STATE; > if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS, > &_vmexit_control) < 0) > return -EIO; > @@ -2360,7 +2362,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf, > VM_ENTRY_LOAD_IA32_EFER | > VM_ENTRY_LOAD_BNDCFGS | > VM_ENTRY_PT_CONCEAL_PIP | > - VM_ENTRY_LOAD_IA32_RTIT_CTL; > + VM_ENTRY_LOAD_IA32_RTIT_CTL | > + VM_ENTRY_LOAD_GUEST_CET_STATE; > if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_ENTRY_CTLS, > &_vmentry_control) < 0) > return -EIO; > @@ -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. > + > 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? > + > + 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 >