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=-8.3 required=3.0 tests=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 040EEC55191 for ; Thu, 23 Apr 2020 17:34:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E5BAD20736 for ; Thu, 23 Apr 2020 17:34:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729955AbgDWRew (ORCPT ); Thu, 23 Apr 2020 13:34:52 -0400 Received: from mga07.intel.com ([134.134.136.100]:32507 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729879AbgDWRew (ORCPT ); Thu, 23 Apr 2020 13:34:52 -0400 IronPort-SDR: RND1g0Ee7IMRsBKx1Pwp/5ML+umHkz5IwRabNBaukWPyV6I2MGmo63xTQAQQTFaSDqhLYMv3aW AqywtyVVvTnQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Apr 2020 10:34:51 -0700 IronPort-SDR: LdsGU0KqTWZLYY2Opbsopap7RtiKwFrI72w+nQN9mdgFoDjia0qw0vyUrgj0vo7PC6M4tU4+Sa WHKKq1/ojUrA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,307,1583222400"; d="scan'208";a="456991546" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by fmsmga005.fm.intel.com with ESMTP; 23 Apr 2020 10:34:50 -0700 Date: Thu, 23 Apr 2020 10:34:50 -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: [PATCH v11 5/9] KVM: X86: Refresh CPUID once guest XSS MSR changes Message-ID: <20200423173450.GJ17824@linux.intel.com> References: <20200326081847.5870-1-weijiang.yang@intel.com> <20200326081847.5870-6-weijiang.yang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200326081847.5870-6-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, Mar 26, 2020 at 04:18:42PM +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. > > 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 | 21 ++++++++++++++++++--- > arch/x86/kvm/x86.c | 9 +++++++-- > 3 files changed, 26 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 24c90ea5ddbd..2c944ad99692 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -650,6 +650,7 @@ struct kvm_vcpu_arch { > > u64 xcr0; > u64 guest_supported_xcr0; > + u64 guest_supported_xss; > u32 guest_xstate_size; > > struct kvm_pio_request pio; > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 78d461be2102..25e9a11291b3 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -95,9 +95,24 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) > } > > 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 (best->eax & (F(XSAVES) | F(XSAVEC))) { Please use cpuid_entry_has() to preserve the automagic register lookup and compile-time assertions that are provided. E.g. I don't know off the top of my whether %eax is the correct register, and I don't want to know :-). > + u64 xstate = vcpu->arch.xcr0 | vcpu->arch.ia32_xss; > + > + best->ebx = xstate_required_size(xstate, true); > + } > + > + if (best->eax & F(XSAVES)) { Same thing here. > + vcpu->arch.guest_supported_xss = > + (best->ecx | ((u64)best->edx << 32)) & supported_xss; The indentation is funky, I'm guessing you're trying to squeak in less than 80 chars. Maybe this? 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; Nit: my preference is to have the high half first, x86 is little endian (the xcr0 code is "wrong" :-D). For me, this also makes it more obvious that the effective size is a u64. > + } else { > + best->ecx = 0; > + best->edx = 0; > + vcpu->arch.guest_supported_xss = 0; > + } > + } 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 90acdbbb8a5a..51ecb496d47d 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -2836,9 +2836,12 @@ 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) > @@ -9635,6 +9638,8 @@ int kvm_arch_hardware_setup(void) > > if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES)) > supported_xss = 0; > + else > + supported_xss = host_xss & KVM_SUPPORTED_XSS; Silly nit: I'd prefer to invert the check, e.g. if (kvm_cpu_cap_has(X86_FEATURE_XSAVES)) supported_xss = host_xss & KVM_SUPPORTED_XSS; else supported_xss = 0; > > cr4_reserved_bits = kvm_host_cr4_reserved_bits(&boot_cpu_data); > > -- > 2.17.2 >