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Shutemov" To: Andy Lutomirski Cc: Chao Peng , Wanpeng Li , jun.nakajima@intel.com, kvm@vger.kernel.org, david@redhat.com, qemu-devel@nongnu.org, "J . Bruce Fields" , linux-mm@kvack.org, "H . Peter Anvin" , ak@linux.intel.com, Jonathan Corbet , Joerg Roedel , x86@kernel.org, Hugh Dickins , Steven Price , Ingo Molnar , "Maciej S . Szmigiero" , Borislav Petkov , Thomas Gleixner , Vitaly Kuznetsov , Vlastimil Babka , Jim Mattson , dave.hansen@intel.com, linux-api@vger.kernel.org, Jeff Layton , linux-kernel@vger.kernel.org, Yu Zhang , "Kirill A . Shutemov" , Sean Christopherson , linux-fsdevel@vger.kernel.org, Paolo Bonzini , Andrew Morton , Vishal Annapurve , Mike Rapoport Subject: Re: [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Message-ID: <20220412195859.gjklfw3fz2lehpb5@box.shutemov.name> References: <20220310140911.50924-1-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 28, 2022 at 01:16:48PM -0700, Andy Lutomirski wrote: > On Thu, Mar 10, 2022 at 6:09 AM Chao Peng wrote: > > > > This is the v5 of this series which tries to implement the fd-based KVM > > guest private memory. The patches are based on latest kvm/queue branch > > commit: > > > > d5089416b7fb KVM: x86: Introduce KVM_CAP_DISABLE_QUIRKS2 > > Can this series be run and a VM booted without TDX? A feature like > that might help push it forward. It would require enlightenment of the guest code. We have two options. Simple one is to limit enabling to the guest kernel, but it would require non-destructive conversion between shared->private memory. This does not seem to be compatible with current design. Other option is get memory private from time 0 of VM boot, but it requires modification of virtual BIOS to setup shared ranges as needed. I'm not sure if anybody volunteer to work on BIOS code to make it happen. Hm. -- Kirill A. Shutemov 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 30398C433EF for ; Tue, 12 Apr 2022 19:58:41 +0000 (UTC) Received: from localhost ([::1]:52636 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1neMeu-0000Wv-8L for qemu-devel@archiver.kernel.org; Tue, 12 Apr 2022 15:58:40 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35012) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1neMdm-0007bO-Gt for qemu-devel@nongnu.org; Tue, 12 Apr 2022 15:57:30 -0400 Received: from mail-lj1-x231.google.com ([2a00:1450:4864:20::231]:39442) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1neMdk-0002qO-Nk for qemu-devel@nongnu.org; Tue, 12 Apr 2022 15:57:30 -0400 Received: by mail-lj1-x231.google.com with SMTP id bn33so25426245ljb.6 for ; Tue, 12 Apr 2022 12:57:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20210112.gappssmtp.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=KPcbiORevCwEqMtvKJH++KF0drE74ilJoT8gFQ34EnA=; b=TSKs9eKW1GlEw++EEPezIbQGa8d6xcrKEr3la4XqzpfJPISA+7b9KTTEm23XMMJ1YV pcXKlpyq55urGdORKzGxmT1pTvZ/5QXhjKImBF6bFGimi25oLZDpt9M2DbzXX/bDQ+u3 9OTNzI18CY7dO2LOX4qCsPXJJ34xmRx72tFYZ9ATSXhsUXzw1klZnP3cX0EZtk+eprNZ tCkMhSq3MAlnJi4/eKNm3VReaN0l0QUhoN+OmB8jE4MWy6cl5AMOOOgXwh+tCG2JI/WG 9+gYtMY/ams5vv8fDesBL9oYXhTRQRnTpXvK1Fa0yRuSW4SuRnnTGhhsM6HBGKFzDmOM KMVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=KPcbiORevCwEqMtvKJH++KF0drE74ilJoT8gFQ34EnA=; b=UbZFvJW59QsQYv1VKkZpCHORhXbpU7dn7zF8+YxwKtQWeWU9edk6LtCxXS36uZFxRX 5/K1WayFTd6oZ1AJmVcKCFz5IT7uFzDAfOfdNgjeXM4yPq7NvTotA9b+Wr/uwo7+50zh +nMeJLTgjCl22Fqb0RtUatmJNnunFhZeLQNjDtpgmyOLLJA8zmEpqZHhIyPuOKrgv1Gz /TNs7jpztHWfN6qkyvtXY5M0TVS2DziCXhyyJ035pqY57f2O5cgjIkHwEYDQVINhjtMo qLUYD23NgP7yKOuIUNQXOglWzsUKjsCUiuuxfCyv6LtsLLDrUU3zlhOZhH5+e4QNBAh6 0mvg== X-Gm-Message-State: AOAM531S9g1RYEjUU5Vnj6iZiG4R2KhW/rH28f2uXsiilnPgVtvGLnky aVLFWzqVFex9nYluu+y9uR9WCg== X-Google-Smtp-Source: ABdhPJzmo2kVaO0teoqOt46A1/R+kt5G8p3jezRBHquWD+rDhCqurcBAW6KPrG7h2kWuiHcT+suCXg== X-Received: by 2002:a2e:a795:0:b0:24c:7f68:b382 with SMTP id c21-20020a2ea795000000b0024c7f68b382mr1118017ljf.494.1649793446359; Tue, 12 Apr 2022 12:57:26 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id g4-20020ac24d84000000b00464f178c0bbsm1843697lfe.96.2022.04.12.12.57.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Apr 2022 12:57:25 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 446751030D2; Tue, 12 Apr 2022 22:58:59 +0300 (+03) Date: Tue, 12 Apr 2022 22:58:59 +0300 From: "Kirill A. Shutemov" To: Andy Lutomirski Subject: Re: [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Message-ID: <20220412195859.gjklfw3fz2lehpb5@box.shutemov.name> References: <20220310140911.50924-1-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Received-SPF: none client-ip=2a00:1450:4864:20::231; envelope-from=kirill@shutemov.name; helo=mail-lj1-x231.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Wanpeng Li , kvm@vger.kernel.org, david@redhat.com, qemu-devel@nongnu.org, "J . Bruce Fields" , linux-mm@kvack.org, "H . Peter Anvin" , Chao Peng , ak@linux.intel.com, Jonathan Corbet , Joerg Roedel , x86@kernel.org, Hugh Dickins , Steven Price , Ingo Molnar , "Maciej S . Szmigiero" , Borislav Petkov , jun.nakajima@intel.com, Thomas Gleixner , Andrew Morton , Vlastimil Babka , Jim Mattson , dave.hansen@intel.com, linux-api@vger.kernel.org, Jeff Layton , linux-kernel@vger.kernel.org, Yu Zhang , Mike Rapoport , Sean Christopherson , linux-fsdevel@vger.kernel.org, Paolo Bonzini , Vitaly Kuznetsov , Vishal Annapurve , "Kirill A . Shutemov" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Mar 28, 2022 at 01:16:48PM -0700, Andy Lutomirski wrote: > On Thu, Mar 10, 2022 at 6:09 AM Chao Peng wrote: > > > > This is the v5 of this series which tries to implement the fd-based KVM > > guest private memory. The patches are based on latest kvm/queue branch > > commit: > > > > d5089416b7fb KVM: x86: Introduce KVM_CAP_DISABLE_QUIRKS2 > > Can this series be run and a VM booted without TDX? A feature like > that might help push it forward. It would require enlightenment of the guest code. We have two options. Simple one is to limit enabling to the guest kernel, but it would require non-destructive conversion between shared->private memory. This does not seem to be compatible with current design. Other option is get memory private from time 0 of VM boot, but it requires modification of virtual BIOS to setup shared ranges as needed. I'm not sure if anybody volunteer to work on BIOS code to make it happen. Hm. -- Kirill A. Shutemov