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,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 B969FC433DF for ; Wed, 22 Jul 2020 20:32:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A5D120709 for ; Wed, 22 Jul 2020 20:32:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726841AbgGVUcH (ORCPT ); Wed, 22 Jul 2020 16:32:07 -0400 Received: from mga09.intel.com ([134.134.136.24]:18047 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726447AbgGVUcH (ORCPT ); Wed, 22 Jul 2020 16:32:07 -0400 IronPort-SDR: XVKPbTjZ3H7ZDlXnwGDfeh354/hFEqiO+dnRK8pgpn/vioMSqpc5bvKIvmMLfLp4Ux9B68BfRo wW2OO0HdRxxw== X-IronPort-AV: E=McAfee;i="6000,8403,9690"; a="151735900" X-IronPort-AV: E=Sophos;i="5.75,383,1589266800"; d="scan'208";a="151735900" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jul 2020 13:32:06 -0700 IronPort-SDR: ERgv1SKH905lV7xuMiYG5qpPdjmoGL8F5IdsGhRRs39KH/fevt5ehukFRppoHiB4QCyYnMS30H o83GeSLC5V0A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,383,1589266800"; d="scan'208";a="362827612" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.152]) by orsmga001.jf.intel.com with ESMTP; 22 Jul 2020 13:32:06 -0700 Date: Wed, 22 Jul 2020 13:32:06 -0700 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 Subject: Re: [RESEND v13 05/11] KVM: x86: Refresh CPUID once guest changes XSS bits Message-ID: <20200722203206.GF9114@linux.intel.com> References: <20200716031627.11492-1-weijiang.yang@intel.com> <20200716031627.11492-6-weijiang.yang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200716031627.11492-6-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 Thu, Jul 16, 2020 at 11:16:21AM +0800, Yang Weijiang wrote: > CPUID(0xd, 1) reports the current required storage size of XCR0 | XSS, > when guest updates the XSS, it's necessary to update the CPUID leaf, otherwise > guest will fetch old state size, and results to some WARN traces during guest > running. > > supported_xss is initialized to host_xss & KVM_SUPPORTED_XSS to indicate current > MSR_IA32_XSS bits supported in KVM, but actual XSS bits seen in guest depends > on the setting of CPUID(0xd,1).{ECX, EDX} for guest. > > Co-developed-by: Zhang Yi Z > Signed-off-by: Zhang Yi Z > Signed-off-by: Yang Weijiang > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/cpuid.c | 23 +++++++++++++++++++---- > arch/x86/kvm/x86.c | 12 ++++++++---- > 3 files changed, 28 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index be5363b21540..e8c749596ba2 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -654,6 +654,7 @@ struct kvm_vcpu_arch { > > u64 xcr0; > u64 guest_supported_xcr0; > + u64 guest_supported_xss; > > struct kvm_pio_request pio; > void *pio_data; > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 8a294f9747aa..d97b2a6e8a8c 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -88,14 +88,29 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) > vcpu->arch.guest_supported_xcr0 = 0; > } else { > vcpu->arch.guest_supported_xcr0 = > - (best->eax | ((u64)best->edx << 32)) & supported_xcr0; > + (((u64)best->edx << 32) | best->eax) & supported_xcr0; While I don't necessarily disagree with the change, it doesn't belong in this patch. > best->ebx = xstate_required_size(vcpu->arch.xcr0, false); > } > > best = kvm_find_cpuid_entry(vcpu, 0xD, 1); > - if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) || > - cpuid_entry_has(best, X86_FEATURE_XSAVEC))) > - best->ebx = xstate_required_size(vcpu->arch.xcr0, true); > + if (best) { > + if (cpuid_entry_has(best, X86_FEATURE_XSAVES) || > + cpuid_entry_has(best, X86_FEATURE_XSAVEC)) { > + u64 xstate = vcpu->arch.xcr0 | vcpu->arch.ia32_xss; > + > + best->ebx = xstate_required_size(xstate, true); > + } > + > + if (!cpuid_entry_has(best, X86_FEATURE_XSAVES)) { > + best->ecx = 0; > + best->edx = 0; > + } > + vcpu->arch.guest_supported_xss = > + (((u64)best->edx << 32) | best->ecx) & supported_xss; > + > + } else { > + vcpu->arch.guest_supported_xss = 0; > + } > > /* > * The existing code assumes virtual address is 48-bit or 57-bit in the > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 906e07039d59..8aed32ff9c0c 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -2912,9 +2912,12 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > * IA32_XSS[bit 8]. Guests have to use RDMSR/WRMSR rather than > * XSAVES/XRSTORS to save/restore PT MSRs. > */ > - if (data & ~supported_xss) > + if (data & ~vcpu->arch.guest_supported_xss) > return 1; > - vcpu->arch.ia32_xss = data; > + if (vcpu->arch.ia32_xss != data) { > + vcpu->arch.ia32_xss = data; > + kvm_update_cpuid(vcpu); > + } > break; > case MSR_SMI_COUNT: > if (!msr_info->host_initiated) > @@ -9779,8 +9782,9 @@ int kvm_arch_hardware_setup(void *opaque) > > memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops)); > > - if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES)) > - supported_xss = 0; > + supported_xss = 0; > + if (kvm_cpu_cap_has(X86_FEATURE_XSAVES)) > + supported_xss = host_xss & KVM_SUPPORTED_XSS; Updating supported_xss in the actual enabling patch. > > #define __kvm_cpu_cap_has(UNUSED_, f) kvm_cpu_cap_has(f) > cr4_reserved_bits = __cr4_reserved_bits(__kvm_cpu_cap_has, UNUSED_); > -- > 2.17.2 >