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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 1661CC43381 for ; Fri, 1 Mar 2019 14:53:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D98C220675 for ; Fri, 1 Mar 2019 14:53:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388868AbfCAOxZ (ORCPT ); Fri, 1 Mar 2019 09:53:25 -0500 Received: from mga09.intel.com ([134.134.136.24]:56043 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728171AbfCAOxY (ORCPT ); Fri, 1 Mar 2019 09:53:24 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 01 Mar 2019 06:53:24 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,427,1544515200"; d="scan'208";a="120134354" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.181]) by orsmga006.jf.intel.com with ESMTP; 01 Mar 2019 06:53:23 -0800 Date: Fri, 1 Mar 2019 06:53:23 -0800 From: Sean Christopherson To: Yang Weijiang Cc: pbonzini@redhat.com, rkrcmar@redhat.com, jmattson@google.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, mst@redhat.com, yu-cheng.yu@intel.com, Zhang Yi Z Subject: Re: [PATCH v3 3/8] KVM:CPUID: Add CPUID support for Guest CET Message-ID: <20190301145323.GB22584@linux.intel.com> References: <20190225132716.6982-1-weijiang.yang@intel.com> <20190225132716.6982-4-weijiang.yang@intel.com> <20190228155939.GD6166@linux.intel.com> <20190228082831.GB12006@local-michael-cet-test.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190228082831.GB12006@local-michael-cet-test.sh.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 28, 2019 at 04:28:32PM +0800, Yang Weijiang wrote: > On Thu, Feb 28, 2019 at 07:59:40AM -0800, Sean Christopherson wrote: > > On Mon, Feb 25, 2019 at 09:27:11PM +0800, Yang Weijiang wrote: > > > Guest CET SHSTK and IBT capability are reported via > > > CPUID.(EAX=7, ECX=0):ECX[bit 7] and EDX[bit 20] respectively. > > > Guest user mode and supervisor mode xsaves component size > > > is reported via CPUID.(EAX=0xD, ECX=1):ECX[bit 11] and ECX[bit 12] > > > respectively. > > > > > > Signed-off-by: Zhang Yi Z > > > Signed-off-by: Yang Weijiang > > > --- > > > arch/x86/kvm/cpuid.c | 60 +++++++++++++++++++++++++++++++++----------- > > > arch/x86/kvm/x86.h | 4 +++ > > > 2 files changed, 50 insertions(+), 14 deletions(-) > > > > > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > > > index cb1aece25b17..5e05756cc6db 100644 > > > --- a/arch/x86/kvm/cpuid.c > > > +++ b/arch/x86/kvm/cpuid.c > > > @@ -65,6 +65,16 @@ u64 kvm_supported_xcr0(void) > > > return xcr0; > > > } > > > > > > +u64 kvm_supported_xss(void) > > > +{ > > > + u64 xss; > > > + > > > + rdmsrl(MSR_IA32_XSS, xss); > > > + xss &= KVM_SUPPORTED_XSS; > > > + return xss; > > > +} > > > +EXPORT_SYMBOL(kvm_supported_xss); > > > + > > > #define F(x) bit(X86_FEATURE_##x) > > > > > > /* For scattered features from cpufeatures.h; we currently expose none */ > > > @@ -323,6 +333,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > > > u32 index, int *nent, int maxnent) > > > { > > > int r; > > > + u32 eax, ebx, ecx, edx; > > > unsigned f_nx = is_efer_nx() ? F(NX) : 0; > > > #ifdef CONFIG_X86_64 > > > unsigned f_gbpages = (kvm_x86_ops->get_lpage_level() == PT_PDPE_LEVEL) > > > @@ -503,6 +514,20 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > > > * if the host doesn't support it. > > > */ > > > entry->edx |= F(ARCH_CAPABILITIES); > > > + > > > + /* > > > + * Guest OS CET enabling is designed independent to > > > + * host enabling, it only has dependency on Host HW > > > + * capability, if it has, report CET support to > > > + * Guest. > > > + */ > > > + cpuid_count(7, 0, &eax, &ebx, &ecx, &edx); > > > + if (ecx & F(SHSTK)) > > > + entry->ecx |= F(SHSTK); > > > + > > > + if (edx & F(IBT)) > > > + entry->edx |= F(IBT); > > > > There's no need to manually add these flags. They will be automatically > > kept if supported in hardware because your previous patch, 02/08, added > > them to the mask of features that can be exposed to the guest, > > i.e. set them in kvm_cpuid_7_0_e{c,d}x_x86_features. > > > I shared the same thought as you before, but after I took a closer look at the > kernel code, actually, when host CET feature is disabled by user via > cmdline options(no_cet_shstk and no_cet_ibt), it'll mask out CET feature bits in > boot_cpu_data.x86_capbility[] array, and cpuid_mask() will make the bits > in previous definition lost, so these lines actually add them back when > host CET is disabled. 'entry' is filled by do_cpuid_1_ent(), which does cpuid_count(), same as your code, i.e. it's not affected by whether or not the host kernel is using each feature. > please check CET kernel patch here: > https://lkml.org/lkml/2018/11/20/204 > > > > + > > > } else { > > > entry->ebx = 0; > > > entry->ecx = 0; > > > @@ -564,14 +589,17 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > > > } > > > case 0xd: { > > > int idx, i; > > > - u64 supported = kvm_supported_xcr0(); > > > + u64 u_supported = kvm_supported_xcr0(); > > > + u64 s_supported = kvm_supported_xss(); > > > + u64 supported; > > > + int compacted; > > > > > > - entry->eax &= supported; > > > - entry->ebx = xstate_required_size(supported, false); > > > + entry->eax &= u_supported; > > > + entry->ebx = xstate_required_size(u_supported, false); > > > entry->ecx = entry->ebx; > > > - entry->edx &= supported >> 32; > > > + entry->edx &= u_supported >> 32; > > > entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; > > > - if (!supported) > > > + if (!u_supported && !s_supported) > > > break; > > > > > > for (idx = 1, i = 1; idx < 64; ++idx) { > > > @@ -583,19 +611,23 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > > > if (idx == 1) { > > > entry[i].eax &= kvm_cpuid_D_1_eax_x86_features; > > > cpuid_mask(&entry[i].eax, CPUID_D_1_EAX); > > > - entry[i].ebx = 0; > > > - if (entry[i].eax & (F(XSAVES)|F(XSAVEC))) > > > - entry[i].ebx = > > > - xstate_required_size(supported, > > > - true); > > > + supported = u_supported | s_supported; > > > + compacted = entry[i].eax & > > > + (F(XSAVES) | F(XSAVEC)); > > > + entry[i].ebx = xstate_required_size(supported, > > > + compacted); > > > + entry[i].ecx &= s_supported; > > > + entry[i].edx = 0; > > > } else { > > > + supported = (entry[i].ecx & 1) ? s_supported : > > > + u_supported; > > > if (entry[i].eax == 0 || !(supported & mask)) > > > continue; > > > - if (WARN_ON_ONCE(entry[i].ecx & 1)) > > > - continue; > > > + entry[i].ecx &= 1; > > > + entry[i].edx = 0; > > > + if (entry[i].ecx) > > > + entry[i].ebx = 0; > > > } > > > - entry[i].ecx = 0; > > > - entry[i].edx = 0; > > > entry[i].flags |= > > > KVM_CPUID_FLAG_SIGNIFCANT_INDEX; > > > ++*nent; > > > diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h > > > index 224cd0a47568..c61da41c3c5c 100644 > > > --- a/arch/x86/kvm/x86.h > > > +++ b/arch/x86/kvm/x86.h > > > @@ -283,6 +283,10 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2, > > > | XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \ > > > | XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \ > > > | XFEATURE_MASK_PKRU) > > > + > > > +#define KVM_SUPPORTED_XSS (XFEATURE_MASK_SHSTK_USER \ > > > + | XFEATURE_MASK_SHSTK_KERNEL) > > > + > > > extern u64 host_xcr0; > > > > > > extern u64 kvm_supported_xcr0(void); > > > -- > > > 2.17.1 > > >