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=-14.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL 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 ED8E4C49ED9 for ; Tue, 10 Sep 2019 23:26:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BAA9B21A4C for ; Tue, 10 Sep 2019 23:26:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="F5hfxo3V" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725957AbfIJX0P (ORCPT ); Tue, 10 Sep 2019 19:26:15 -0400 Received: from mail-io1-f68.google.com ([209.85.166.68]:46260 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725876AbfIJX0O (ORCPT ); Tue, 10 Sep 2019 19:26:14 -0400 Received: by mail-io1-f68.google.com with SMTP id d17so19677033ios.13 for ; Tue, 10 Sep 2019 16:26:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=e0yMAkPqiKPir+n1j8srB24VKkYYyhVMoQLwVTHaJAc=; b=F5hfxo3VvPyW7ojgUmJqvhUktD7sMP9xDzj+DFoZ88d8ia3Vd0ZmXEsraxB2/vRsCD rctWKj9LzlBhilWvG6PmIJ9im1oIFyUbPUyDYcPdTw63QdsCa/H04s3A+xNx1c6VsLmm HSr99EUMroIaQsmyEMr5w8SqObju+2JsNdfMwBhPeBghAIa3njNUmfCu/iTUYe6pN8Wd Ub+jgmogPo917589VAJDiPusnCsLa8wyDxT2TdC9KMdLBg9QKkOjhkZiTIJxU+p9orzd m7urN9oO0a/joh2eQe/x5hhXecHBp3pZOwvatyrSrd4SJSZAo2fj/g2baJbukhEVO1tR qJFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=e0yMAkPqiKPir+n1j8srB24VKkYYyhVMoQLwVTHaJAc=; b=Kgn89fc+g6PA8EhZdnEanHsYCiMWUhKywIudJW0AerFjg04MyYScQgMUtRR5OjnnbP zpbkg3qkAMXurvgU9e9LSukan2Ya9dRPDfqkgPQ4fqWoLiJRye9fHl38PtMSr2jB1skK cnHCZgcy2L1g0agC4JF0ZmbYbNTHiv/baaYVsyBBXG44zKoouOSp/kJ33xYXKk9wDvdE YmIwgiMxPUbJJ/hgyDzCXNRI9AtNibyigT9rR7SKJr5E1iBXDm7G1mgdCI+es9qAjfzo M+5JIVcM92eM403APSLQJA+wnjOUcYORfN6E1vfDQGHNBzemh/QAhZbym0znYGc1xB/0 zrGg== X-Gm-Message-State: APjAAAXlC97BsIMLDRmr/mKRjIb9Wvp5+JfeTXA7p9SsVrPjKrVbcoVi pFPjHB+KAj3GZS3ULYjn/zmOVsM4TQ5jJxX+Xbp1zA== X-Google-Smtp-Source: APXvYqw/eFb+doTO+2UWGPL9XspAj/mEase+WvrKdTMQ73DT1YoCNrqr4LHf9Fap8Z/Bp82rin4Y7oQ+6tFASrg1CA0= X-Received: by 2002:a5e:a80a:: with SMTP id c10mr1594653ioa.122.1568157973660; Tue, 10 Sep 2019 16:26:13 -0700 (PDT) MIME-Version: 1.0 References: <20190910102742.47729-1-xiaoyao.li@intel.com> <20190910102742.47729-3-xiaoyao.li@intel.com> <6ce6567e286b4432d62a730dd1697a3592c36a82.camel@intel.com> In-Reply-To: <6ce6567e286b4432d62a730dd1697a3592c36a82.camel@intel.com> From: Jim Mattson Date: Tue, 10 Sep 2019 16:26:02 -0700 Message-ID: Subject: Re: [PATCH v2 2/2] KVM: CPUID: Put maxphyaddr updating together with virtual address width checking To: Xiaoyao Li Cc: Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Joerg Roedel , kvm list Content-Type: text/plain; charset="UTF-8" Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Sep 10, 2019 at 3:52 PM Xiaoyao Li wrote: > > On Tue, 2019-09-10 at 10:13 -0700, Jim Mattson wrote: > > On Tue, Sep 10, 2019 at 3:42 AM Xiaoyao Li wrote: > > > > > > Since both of maxphyaddr updating and virtual address width checking > > > need to query the cpuid leaf 0x80000008. We can put them together. > > > > > > Signed-off-by: Xiaoyao Li > > > --- > > > arch/x86/kvm/cpuid.c | 6 ++++-- > > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > > > index 67fa44ab87af..fd0a66079001 100644 > > > --- a/arch/x86/kvm/cpuid.c > > > +++ b/arch/x86/kvm/cpuid.c > > > @@ -118,6 +118,7 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) > > > best->ebx = xstate_required_size(vcpu->arch.xcr0, true); > > > > > > /* > > > + * Update physical address width and check virtual address width. > > > * The existing code assumes virtual address is 48-bit or 57-bit in > > > the > > > * canonical address checks; exit if it is ever changed. > > > */ > > > @@ -127,7 +128,10 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) > > > > > > if (vaddr_bits != 48 && vaddr_bits != 57 && vaddr_bits != 0) > > > return -EINVAL; > > > + > > > + vcpu->arch.maxphyaddr = best->eax & 0xff; > > > } > > > + vcpu->arch.maxphyaddr = 36; > > > > Perhaps I'm missing something, but it looks to me like you always set > > vcpu->arch.maxphyaddr to 36, regardless of what may be enumerated by > > leaf 0x80000008. > > Oh, I made a stupid mistake. It should be included in the else case. > > > > > Is there really much of an advantage to open-coding > > cpuid_query_maxphyaddr() here? > > Indeed not so much. > It can avoid two more kvm_find_cpuid_entry() calling that we don't handle leaf > 0x80000008 twice in two place. I'm inclined to leave things as they are. As your previous attempt demonstrates, having the same logic replicated in multiple places is prone to error. I can't imagine that this would be a performance-sensitive path. > > > best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0); > > > if (kvm_hlt_in_guest(vcpu->kvm) && best && > > > @@ -144,8 +148,6 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) > > > } > > > } > > > > > > - /* Update physical-address width */ > > > - vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu); > > > kvm_mmu_reset_context(vcpu); > > > > > > kvm_pmu_refresh(vcpu); > > > -- > > > 2.19.1 > > > >