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 ADC9CC55194 for ; Fri, 24 Apr 2020 14:05:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9868520776 for ; Fri, 24 Apr 2020 14:05:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727774AbgDXOFy (ORCPT ); Fri, 24 Apr 2020 10:05:54 -0400 Received: from mga11.intel.com ([192.55.52.93]:32011 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726968AbgDXOFy (ORCPT ); Fri, 24 Apr 2020 10:05:54 -0400 IronPort-SDR: qL1izba6z5ZhxCOgJp/XB1tPtG2pk9SDAgdvmBi25OK7Nn//Dwg/ZLw58kClErbARcvT6nADmM bI5Tt/1erMHQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Apr 2020 07:05:52 -0700 IronPort-SDR: 4UElGFTvdSIDCKBdl8gBliJHKUIGJSN6Kys9Yjm3CqmNII/Bb4WohMbL/jtyQ0V3yh8rxWkRsV B4PYdjCLbcgw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,311,1583222400"; d="scan'208";a="457353752" Received: from unknown (HELO localhost) ([10.239.159.128]) by fmsmga005.fm.intel.com with ESMTP; 24 Apr 2020 07:05:49 -0700 Date: Fri, 24 Apr 2020 22:07:51 +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 Subject: Re: [PATCH v11 2/9] KVM: VMX: Set guest CET MSRs per KVM and host configuration Message-ID: <20200424140751.GE24039@local-michael-cet-test> References: <20200326081847.5870-1-weijiang.yang@intel.com> <20200326081847.5870-3-weijiang.yang@intel.com> <20200423162749.GG17824@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200423162749.GG17824@linux.intel.com> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Apr 23, 2020 at 09:27:49AM -0700, Sean Christopherson wrote: > On Thu, Mar 26, 2020 at 04:18:39PM +0800, Yang Weijiang wrote: > > @@ -3033,6 +3033,13 @@ void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) > > vmcs_writel(GUEST_CR3, guest_cr3); > > } > > > > +static bool is_cet_mode_allowed(struct kvm_vcpu *vcpu, u32 mode_mask) > > CET itself isn't a mode. And since this ends up being an inner helper for > is_cet_supported(), I think __is_cet_supported() would be the way to go. > > Even @mode_mask is a bit confusing without the context of it being kernel > vs. user. The callers are very readable, e.g. I'd much prefer passing the > mask as opposed to doing 'bool kernel'. Maybe s/mode_mask/cet_mask? That > doesn't exactly make things super clear, but at least the reader knows the > mask is for CET features. Make sense, will change it. > > > +{ > > + return ((supported_xss & mode_mask) && > > + (guest_cpuid_has(vcpu, X86_FEATURE_SHSTK) || > > + guest_cpuid_has(vcpu, X86_FEATURE_IBT))); > > +} > > + > > int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) > > { > > struct vcpu_vmx *vmx = to_vmx(vcpu); > > @@ -7064,6 +7071,35 @@ static void update_intel_pt_cfg(struct kvm_vcpu *vcpu) > > vmx->pt_desc.ctl_bitmask &= ~(0xfULL << (32 + i * 4)); > > } > > > > +static void vmx_update_intercept_for_cet_msr(struct kvm_vcpu *vcpu) > > +{ > > + struct vcpu_vmx *vmx = to_vmx(vcpu); > > + unsigned long *msr_bitmap = vmx->vmcs01.msr_bitmap; > > + bool flag; > > Maybe s/flag/incpt or something to make it more obvious that the bool is > true if we want to intercept? vmx_set_intercept_for_msr()s's @value isn't > any better :-/. I prefer using incpt now ;-) > > + > > + flag = !is_cet_mode_allowed(vcpu, XFEATURE_MASK_CET_USER); > > + /* > > + * U_CET is required for USER CET, and U_CET, PL3_SPP are bound as > > + * one component and controlled by IA32_XSS[bit 11]. > > + */ > > + vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_U_CET, MSR_TYPE_RW, flag); > > + vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_PL3_SSP, MSR_TYPE_RW, flag); > > + > > + flag = !is_cet_mode_allowed(vcpu, XFEATURE_MASK_CET_KERNEL); > > + /* > > + * S_CET is required for KERNEL CET, and PL0_SSP ... PL2_SSP are > > + * bound as one component and controlled by IA32_XSS[bit 12]. > > + */ > > + vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_S_CET, MSR_TYPE_RW, flag); > > + vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_PL0_SSP, MSR_TYPE_RW, flag); > > + vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_PL1_SSP, MSR_TYPE_RW, flag); > > + vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_PL2_SSP, MSR_TYPE_RW, flag); > > + > > + flag |= !guest_cpuid_has(vcpu, X86_FEATURE_SHSTK); > > + /* SSP_TAB is only available for KERNEL SHSTK.*/ > > + vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_INT_SSP_TAB, MSR_TYPE_RW, flag); > > +} > > + > > static void vmx_cpuid_update(struct kvm_vcpu *vcpu) > > { > > struct vcpu_vmx *vmx = to_vmx(vcpu); > > @@ -7102,6 +7138,10 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu) > > vmx_set_guest_msr(vmx, msr, enabled ? 0 : TSX_CTRL_RTM_DISABLE); > > } > > } > > + > > + if (guest_cpuid_has(vcpu, X86_FEATURE_SHSTK) || > > + guest_cpuid_has(vcpu, X86_FEATURE_IBT)) > > + vmx_update_intercept_for_cet_msr(vcpu); > > This is wrong, it will miss the case where userspace double configures CPUID > and goes from CET=1 to CET=0. This should instead be: > > if (supported_xss & (XFEATURE_MASK_CET_KERNEL | XFEATURE_MASK_CET_USER)) > vmx_update_intercept_for_cet_msr(vcpu); > > > } Here CET=1/0, did you mean the CET bit in XSS or CR4.CET? If it's the former, then it's OK for me. > > > > static __init void vmx_set_cpu_caps(void) > > -- > > 2.17.2 > >