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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 04D4AC43334 for ; Thu, 16 Jun 2022 10:21:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229870AbiFPKVb (ORCPT ); Thu, 16 Jun 2022 06:21:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38458 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229479AbiFPKV3 (ORCPT ); Thu, 16 Jun 2022 06:21:29 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 03F885D5F0 for ; Thu, 16 Jun 2022 03:21:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655374885; 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=1w6kfhI5BLQxYZjNyCbEc+mC0M3DMAszPSrEnT91i7U=; b=d/w3TgM+16OVe+qcOmHk/b8PsHk3fUv0idY06/ZQD8+6zOJaXuW1DWiW/vqcAa+EmkhV/0 xg8NoLRvg9BZ3TxYab9/yugomMrLHxDp6DhQ8tBtbKs4qTng++1o8tC07f+XreZ6IJhD6I InNaAEF2RKEONfCN0ofQk+RBvosTj8I= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-167-Hjd_5049P_qzexEUNbFIZg-1; Thu, 16 Jun 2022 06:21:24 -0400 X-MC-Unique: Hjd_5049P_qzexEUNbFIZg-1 Received: by mail-ed1-f69.google.com with SMTP id cy18-20020a0564021c9200b0042dc7b4f36fso963312edb.4 for ; Thu, 16 Jun 2022 03:21:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent :content-language:to:cc:references:from:subject:in-reply-to :content-transfer-encoding; bh=1w6kfhI5BLQxYZjNyCbEc+mC0M3DMAszPSrEnT91i7U=; b=1Tc0Hkj7/XhZaUpBrO0phbJGwHi1m06hrQ2CV7Z0e2YdkDHHLQhTJqRv+vnqdVtuaX oCP2Hg7sblyvihFj7S+iSYIWMGW55/MjC7d5rFlXnfWZshlaazWeSkYMzKoKJpIja2Ob stUtND6cirCEU5KEnEt4Gf97tVXiKYVtu5Ln1ZcQTodWixKc2pqeoNKEAM2v+Oi1tO/+ 6ptK/J+3z4wjMVGfQRHx21YqmuevS9CxBzouetoni0A24K49WwTPb4ny4r6HieF8xOpk ok8mkYui38bf8yNFeQkgi6/3bnZrMIoCUaw7Ku5GuACSh+NvrG0aDH5TiGKk3r23VpKp lw9A== X-Gm-Message-State: AJIora/aC5xLLYHzXcgMVYXe3cTJTBZ6gch5BO5VQ2R15NMjCjknwgzO c5gAJ+QkI2CCiuzpEAu8VBmzPoepLDuk4iCbkFoWe2mRPj0yYVpt6es93RJZxeVFa7sLJ1XvCen L5I11XW4Z8NuJMMuFu/i2JUde X-Received: by 2002:a17:906:3793:b0:702:eea9:843a with SMTP id n19-20020a170906379300b00702eea9843amr3748379ejc.465.1655374883396; Thu, 16 Jun 2022 03:21:23 -0700 (PDT) X-Google-Smtp-Source: AGRyM1tgCWmsWMJUg/6tveJy1I3YO0SejWe+BvTvhEDY4zt/3QRTQGEueFH0aeakfSd9pTKp03hBGw== X-Received: by 2002:a17:906:3793:b0:702:eea9:843a with SMTP id n19-20020a170906379300b00702eea9843amr3748363ejc.465.1655374883212; Thu, 16 Jun 2022 03:21:23 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:9af8:e5f5:7516:fa89? ([2001:b07:6468:f312:9af8:e5f5:7516:fa89]) by smtp.googlemail.com with ESMTPSA id 9-20020a170906310900b006fe8b456672sm620540ejx.3.2022.06.16.03.21.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Jun 2022 03:21:22 -0700 (PDT) Message-ID: <62d4f7f0-e7b2-83ad-a2c7-a90153129da2@redhat.com> Date: Thu, 16 Jun 2022 12:21:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Content-Language: en-US To: Peter Zijlstra , Yang Weijiang Cc: seanjc@google.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, rick.p.edgecombe@intel.com References: <20220616084643.19564-1-weijiang.yang@intel.com> From: Paolo Bonzini Subject: Re: [PATCH 00/19] Refresh queued CET virtualization series In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/16/22 12:12, Peter Zijlstra wrote: > Do I understand this right in that a host without X86_KERNEL_IBT cannot > run a guest with X86_KERNEL_IBT on? That seems unfortunate, since that > was exactly what I did while developing the X86_KERNEL_IBT patches. > > I'm thinking that if the hardware supports it, KVM should expose it, > irrespective of the host kernel using it. For IBT in particular, I think all processor state is only loaded and stored at vmentry/vmexit (does not need XSAVES), so it should be feasible. Paolo