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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,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 0DB73C433E3 for ; Thu, 13 Aug 2020 04:54:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E867C20855 for ; Thu, 13 Aug 2020 04:54:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725949AbgHMEy3 (ORCPT ); Thu, 13 Aug 2020 00:54:29 -0400 Received: from mga02.intel.com ([134.134.136.20]:63538 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725747AbgHMEy3 (ORCPT ); Thu, 13 Aug 2020 00:54:29 -0400 IronPort-SDR: ImVL/sZbYaeo8e+K5Gan+SNc3rBEUb0Pmp1dx1YGNNaLnp2gOE6LcZwgjhOWaccP58PKAQp/zg T6wCV+nxhDug== X-IronPort-AV: E=McAfee;i="6000,8403,9711"; a="142001557" X-IronPort-AV: E=Sophos;i="5.76,307,1592895600"; d="scan'208";a="142001557" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2020 21:54:28 -0700 IronPort-SDR: mLOlVFMGG1+lMAWVCHxdsWhNcEll08QkHk3MO5+6k0H92Vp3SeZE22GlGR040akuQfCvqJSkkL nZxkCWHafZxw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,307,1592895600"; d="scan'208";a="325296166" Received: from cqiang-mobl.ccr.corp.intel.com (HELO [10.238.2.93]) ([10.238.2.93]) by orsmga008.jf.intel.com with ESMTP; 12 Aug 2020 21:54:26 -0700 Subject: Re: [RFC 7/7] KVM: VMX: Enable PKS for nested VM To: Jim Mattson Cc: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Joerg Roedel , Xiaoyao Li , kvm list , LKML References: <20200807084841.7112-1-chenyi.qiang@intel.com> <20200807084841.7112-8-chenyi.qiang@intel.com> From: Chenyi Qiang Message-ID: <1481a482-c20b-5531-736c-de0c5d3d611c@intel.com> Date: Thu, 13 Aug 2020 12:52:40 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 8/11/2020 8:05 AM, Jim Mattson wrote: > On Fri, Aug 7, 2020 at 1:47 AM Chenyi Qiang wrote: >> >> PKS MSR passes through guest directly. Configure the MSR to match the >> L0/L1 settings so that nested VM runs PKS properly. >> >> Signed-off-by: Chenyi Qiang >> --- >> arch/x86/kvm/vmx/nested.c | 32 ++++++++++++++++++++++++++++++++ >> arch/x86/kvm/vmx/vmcs12.c | 2 ++ >> arch/x86/kvm/vmx/vmcs12.h | 6 +++++- >> arch/x86/kvm/vmx/vmx.c | 10 ++++++++++ >> arch/x86/kvm/vmx/vmx.h | 1 + >> 5 files changed, 50 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c >> index df2c2e733549..1f9823d21ecd 100644 >> --- a/arch/x86/kvm/vmx/nested.c >> +++ b/arch/x86/kvm/vmx/nested.c >> @@ -647,6 +647,12 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu, >> MSR_IA32_PRED_CMD, >> MSR_TYPE_W); >> >> + if (!msr_write_intercepted_l01(vcpu, MSR_IA32_PKRS)) >> + nested_vmx_disable_intercept_for_msr( >> + msr_bitmap_l1, msr_bitmap_l0, >> + MSR_IA32_PKRS, >> + MSR_TYPE_R | MSR_TYPE_W); > > What if L1 intercepts only *reads* of MSR_IA32_PKRS? > >> kvm_vcpu_unmap(vcpu, &to_vmx(vcpu)->nested.msr_bitmap_map, false); >> >> return true; > >> @@ -2509,6 +2519,11 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, >> if (kvm_mpx_supported() && (!vmx->nested.nested_run_pending || >> !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS))) >> vmcs_write64(GUEST_BNDCFGS, vmx->nested.vmcs01_guest_bndcfgs); >> + >> + if (kvm_cpu_cap_has(X86_FEATURE_PKS) && > > Is the above check superfluous? I would assume that the L1 guest can't > set VM_ENTRY_LOAD_IA32_PKRS unless this is true. > I enforce this check to ensure vmcs_write to the Guest_IA32_PKRS without error. if deleted, vmcs_write to GUEST_IA32_PKRS may executed when PKS is unsupported. >> + (!vmx->nested.nested_run_pending || >> + !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PKRS))) >> + vmcs_write64(GUEST_IA32_PKRS, vmx->nested.vmcs01_guest_pkrs); > > This doesn't seem right to me. On the target of a live migration, with > L2 active at the time the snapshot was taken (i.e., > vmx->nested.nested_run_pending=0), it looks like we're going to try to > overwrite the current L2 PKRS value with L1's PKRS value (except that > in this situation, vmx->nested.vmcs01_guest_pkrs should actually be > 0). Am I missing something? > We overwrite the L2 PKRS with L1's value when L2 doesn't support PKS. Because the L1's VM_ENTRY_LOAD_IA32_PKRS is off, we need to migrate L1's PKRS to L2. >> vmx_set_rflags(vcpu, vmcs12->guest_rflags); >> >> /* EXCEPTION_BITMAP and CR0_GUEST_HOST_MASK should basically be the > > >> @@ -3916,6 +3943,8 @@ 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_cpu_cap_has(X86_FEATURE_PKS)) > > Shouldn't we be checking to see if the *virtual* CPU supports PKS > before writing anything into vmcs12->guest_ia32_pkrs? > Yes, It's reasonable. >> + vmcs12->guest_ia32_pkrs = vmcs_read64(GUEST_IA32_PKRS); >> >> vmx->nested.need_sync_vmcs02_to_vmcs12_rare = false; >> }