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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 8515AC433E0 for ; Mon, 8 Mar 2021 07:49:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3EA9C65134 for ; Mon, 8 Mar 2021 07:49:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231176AbhCHHsu (ORCPT ); Mon, 8 Mar 2021 02:48:50 -0500 Received: from mga18.intel.com ([134.134.136.126]:17192 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231195AbhCHHsd (ORCPT ); Mon, 8 Mar 2021 02:48:33 -0500 IronPort-SDR: /UE+lyvPJsNUhuc03PMTE/g2QPXHqKAfEf8Bi4nB4ilNyd3cXJ3XSAZ8eqmB3jMmVrlK4EEIgG S6wNZABj0ZNw== X-IronPort-AV: E=McAfee;i="6000,8403,9916"; a="175598054" X-IronPort-AV: E=Sophos;i="5.81,231,1610438400"; d="scan'208";a="175598054" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Mar 2021 23:48:33 -0800 IronPort-SDR: +ebTyNZM3wupNkoQprJ1QH7EdxENAsN7Ba4Ijt9e69Y6Y0L2LWYogutPOPv981RQhJmBT/p568 CgFi/1l5EI/A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,231,1610438400"; d="scan'208";a="369341148" Received: from local-michael-cet-test.sh.intel.com (HELO localhost) ([10.239.159.166]) by orsmga003.jf.intel.com with ESMTP; 07 Mar 2021 23:48:31 -0800 Date: Mon, 8 Mar 2021 16:01:09 +0800 From: Yang Weijiang To: Sean Christopherson Cc: Yang Weijiang , pbonzini@redhat.com, vkuznets@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/3] KVM: nVMX: Sync L2 guest CET states between L1/L2 Message-ID: <20210308080108.GA1160@local-michael-cet-test.sh.intel.com> References: <20210304060740.11339-1-weijiang.yang@intel.com> <20210304060740.11339-2-weijiang.yang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Mar 04, 2021 at 08:46:45AM -0800, Sean Christopherson wrote: > On Thu, Mar 04, 2021, Yang Weijiang wrote: > > @@ -3375,6 +3391,12 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, > > if (kvm_mpx_supported() && > > !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS)) > > vmx->nested.vmcs01_guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS); > > + if (kvm_cet_supported() && > > + !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE)) { > > Alignment. > > > + vmx->nested.vmcs01_guest_ssp = vmcs_readl(GUEST_SSP); > > + vmx->nested.vmcs01_guest_s_cet = vmcs_readl(GUEST_S_CET); > > + vmx->nested.vmcs01_guest_ssp_tbl = vmcs_readl(GUEST_INTR_SSP_TABLE); > > + } > > > > /* > > * Overwrite vmcs01.GUEST_CR3 with L1's CR3 if EPT is disabled *and* > > @@ -4001,6 +4023,9 @@ static bool is_vmcs12_ext_field(unsigned long field) > > case GUEST_IDTR_BASE: > > case GUEST_PENDING_DBG_EXCEPTIONS: > > case GUEST_BNDCFGS: > > + case GUEST_SSP: > > + case GUEST_INTR_SSP_TABLE: > > + case GUEST_S_CET: > > return true; > > default: > > break; > > @@ -4052,6 +4077,11 @@ static void sync_vmcs02_to_vmcs12_rare(struct kvm_vcpu *vcpu, > > vmcs_readl(GUEST_PENDING_DBG_EXCEPTIONS); > > if (kvm_mpx_supported()) > > vmcs12->guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS); > > + if (kvm_cet_supported()) { > > Isn't the existing kvm_mpx_supported() check wrong in the sense that KVM only > needs to sync to vmcs12 if KVM and the guest both support MPX? For MPX, if guest_cpuid_has() is not efficent, can it be checked by BNDCFGS EN bit? E.g.: if (kvm_mpx_supported() && (vmcs12->guest_bndcfgs & 1)) > Same would apply to CET. Not sure it'd be a net positive in terms of performance since > guest_cpuid_has() can be quite slow, but overwriting vmcs12 fields that technically don't exist > feels wrong. For CET, can we get equivalent effect by checking vmcs12->guest_cr4.CET? E.g.: if (kvm_cet_supported() && (vmcs12->guest_cr4 & X86_CR4_CET)) > > > + vmcs12->guest_ssp = vmcs_readl(GUEST_SSP); > > + vmcs12->guest_s_cet = vmcs_readl(GUEST_S_CET); > > + vmcs12->guest_ssp_tbl = vmcs_readl(GUEST_INTR_SSP_TABLE); > > + } > > > > vmx->nested.need_sync_vmcs02_to_vmcs12_rare = false; > > } > > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h > > index 9d3a557949ac..36dc4fdb0909 100644 > > --- a/arch/x86/kvm/vmx/vmx.h > > +++ b/arch/x86/kvm/vmx/vmx.h > > @@ -155,6 +155,9 @@ struct nested_vmx { > > /* to migrate it to L2 if VM_ENTRY_LOAD_DEBUG_CONTROLS is off */ > > u64 vmcs01_debugctl; > > u64 vmcs01_guest_bndcfgs; > > + u64 vmcs01_guest_ssp; > > + u64 vmcs01_guest_s_cet; > > + u64 vmcs01_guest_ssp_tbl; > > > > /* to migrate it to L1 if L2 writes to L1's CR8 directly */ > > int l1_tpr_threshold; > > -- > > 2.26.2 > >