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=-12.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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=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 48287C2D0E2 for ; Wed, 23 Sep 2020 13:45:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB9A821BE5 for ; Wed, 23 Sep 2020 13:45:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ReEgkbug" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726716AbgIWNpT (ORCPT ); Wed, 23 Sep 2020 09:45:19 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:40410 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726636AbgIWNpT (ORCPT ); Wed, 23 Sep 2020 09:45:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600868716; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QG/XpftCpbOncz4MqVk/ddxYXgT+Lw6rTWS+CEJwsqw=; b=ReEgkbugASa+6SobL6eqkznxF5lT2rg/URIBOqcw5Ufy3qCvjs4mdsfdfumBeLLohupLhi eKiEH/rFnmofpYhz3XrDAW7KQNDnBQ4d5Au2l9bp+K9pBLtzDdWvkWUQvOWuF3ZSS9FZ8G iE9nqw0ZV8VPt0SiV3rcNKuZ4YFn88M= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-250-KqIyla3VMuqmTLn_sF1zYw-1; Wed, 23 Sep 2020 09:45:13 -0400 X-MC-Unique: KqIyla3VMuqmTLn_sF1zYw-1 Received: by mail-wr1-f69.google.com with SMTP id a12so8847659wrg.13 for ; Wed, 23 Sep 2020 06:45:13 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=QG/XpftCpbOncz4MqVk/ddxYXgT+Lw6rTWS+CEJwsqw=; b=q7tLBEdQgwPk2nGFOAjdACR4/SnkRPvesM+g/HMyIOfgxAB/iX74FP9mWX02G2XYrv MAJPxk3wWQ3Hmw/17TvU53K1T+HEJX+WrCqBJtCb3v7RXT+xTdbWgtfVy7NcalCKfOxY vv5DZOQ2JylOyZBwugd6SHE/F3zHb4Zm3qumqK+b1Dan5vFR7jTY24HFRl0WThIlunT+ 9fGo9HL0rQURbpjuiu/lqc5DyrNudekcDJkK2wQfxyM75TjhiWzJLhQqNeaYBSPR7xwP bPIMdMmSJZOcdJ8BS0u3hzU5x4/X/WAk2fhutAXquzX17qDsEoaC7LHe9Ng7hzUewW+2 bVRw== X-Gm-Message-State: AOAM533XJ9PjnXkduip/rWP5DBobCBauu8PMGTREgH82xS8wZUXFewAf eRIkNQnW2bZPcDpf7dNh8X+uXbOUzZsYkvDRH7hqtdx5Tm4ruLzWUAgixAP4RwAmZ68oL1N8tDw QKI0d55RS7DKhDBsb8mlFyCon X-Received: by 2002:a5d:4f12:: with SMTP id c18mr894640wru.33.1600868712235; Wed, 23 Sep 2020 06:45:12 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyb3cleun1Mcb1EtEe3QbBYzLOy6zExpHXgfTHp4hlVL/wCgtWG6/xhTdTSb3C3JjWrxKZ/Hw== X-Received: by 2002:a5d:4f12:: with SMTP id c18mr894615wru.33.1600868711914; Wed, 23 Sep 2020 06:45:11 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:15f1:648d:7de6:bad9? ([2001:b07:6468:f312:15f1:648d:7de6:bad9]) by smtp.gmail.com with ESMTPSA id 97sm32423184wrm.15.2020.09.23.06.45.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Sep 2020 06:45:10 -0700 (PDT) Subject: Re: [PATCH] KVM: x86: VMX: Make smaller physical guest address space support user-configurable To: Mohammed Gamal , kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, sean.j.christopherson@intel.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org References: <20200903141122.72908-1-mgamal@redhat.com> From: Paolo Bonzini Message-ID: <8c7ce8ff-a212-a974-3829-c45eb5335651@redhat.com> Date: Wed, 23 Sep 2020 15:45:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200903141122.72908-1-mgamal@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/09/20 16:11, Mohammed Gamal wrote: > This patch exposes allow_smaller_maxphyaddr to the user as a module parameter. > > Since smaller physical address spaces are only supported on VMX, the parameter > is only exposed in the kvm_intel module. > Modifications to VMX page fault and EPT violation handling will depend on whether > that parameter is enabled. > > Also disable support by default, and let the user decide if they want to enable > it. > > Signed-off-by: Mohammed Gamal > --- > arch/x86/kvm/vmx/vmx.c | 15 ++++++--------- > arch/x86/kvm/vmx/vmx.h | 3 +++ > arch/x86/kvm/x86.c | 2 +- > 3 files changed, 10 insertions(+), 10 deletions(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 819c185adf09..dc778c7b5a06 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -129,6 +129,9 @@ static bool __read_mostly enable_preemption_timer = 1; > module_param_named(preemption_timer, enable_preemption_timer, bool, S_IRUGO); > #endif > > +extern bool __read_mostly allow_smaller_maxphyaddr; > +module_param(allow_smaller_maxphyaddr, bool, S_IRUGO | S_IWUSR); > + > #define KVM_VM_CR0_ALWAYS_OFF (X86_CR0_NW | X86_CR0_CD) > #define KVM_VM_CR0_ALWAYS_ON_UNRESTRICTED_GUEST X86_CR0_NE > #define KVM_VM_CR0_ALWAYS_ON \ > @@ -4798,7 +4801,8 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu) > > if (is_page_fault(intr_info)) { > cr2 = vmx_get_exit_qual(vcpu); > - if (enable_ept && !vcpu->arch.apf.host_apf_flags) { > + if (enable_ept && !vcpu->arch.apf.host_apf_flags > + && allow_smaller_maxphyaddr) { > /* > * EPT will cause page fault only if we need to > * detect illegal GPAs. > @@ -5331,7 +5335,7 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu) > * would also use advanced VM-exit information for EPT violations to > * reconstruct the page fault error code. > */ > - if (unlikely(kvm_mmu_is_illegal_gpa(vcpu, gpa))) > + if (unlikely(kvm_mmu_is_illegal_gpa(vcpu, gpa)) && allow_smaller_maxphyaddr) > return kvm_emulate_instruction(vcpu, 0); > > return kvm_mmu_page_fault(vcpu, gpa, error_code, NULL, 0); > @@ -8303,13 +8307,6 @@ static int __init vmx_init(void) > #endif > vmx_check_vmcs12_offsets(); > > - /* > - * Intel processors don't have problems with > - * GUEST_MAXPHYADDR < HOST_MAXPHYADDR so enable > - * it for VMX by default > - */ > - allow_smaller_maxphyaddr = true; > - > return 0; > } > module_init(vmx_init); > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h > index 26175a4759fa..b859435efa2e 100644 > --- a/arch/x86/kvm/vmx/vmx.h > +++ b/arch/x86/kvm/vmx/vmx.h > @@ -551,6 +551,9 @@ static inline bool vmx_has_waitpkg(struct vcpu_vmx *vmx) > > static inline bool vmx_need_pf_intercept(struct kvm_vcpu *vcpu) > { > + if (!allow_smaller_maxphyaddr) > + return false; > + > return !enable_ept || cpuid_maxphyaddr(vcpu) < boot_cpu_data.x86_phys_bits; This needs to return true if !enable_ept. if (!enable_ept) return true; return allow_smaller_maxphyaddr && cpuid_maxphyaddr(vcpu) < boot_cpu_data.x86_phys_bits; Fixed and queued, thanks. Paolo > } > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index d39d6cf1d473..982f1d73a884 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -188,7 +188,7 @@ static struct kvm_shared_msrs __percpu *shared_msrs; > u64 __read_mostly host_efer; > EXPORT_SYMBOL_GPL(host_efer); > > -bool __read_mostly allow_smaller_maxphyaddr; > +bool __read_mostly allow_smaller_maxphyaddr = 0; > EXPORT_SYMBOL_GPL(allow_smaller_maxphyaddr); > > static u64 __read_mostly host_xss; >