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 626E0C433EF for ; Mon, 6 Dec 2021 17:51:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344731AbhLFRyr (ORCPT ); Mon, 6 Dec 2021 12:54:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344076AbhLFRyr (ORCPT ); Mon, 6 Dec 2021 12:54:47 -0500 Received: from mail-pf1-x435.google.com (mail-pf1-x435.google.com [IPv6:2607:f8b0:4864:20::435]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 41ACBC0613F8 for ; Mon, 6 Dec 2021 09:51:18 -0800 (PST) Received: by mail-pf1-x435.google.com with SMTP id g18so10869967pfk.5 for ; Mon, 06 Dec 2021 09:51:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=+ESPc86/WR8zjQO6sLQzuGtCJWQp0GHtvc/0bwINti8=; b=mEM23FJPPrJVfglUbFra6ClSwRonXW32XC/+wLGHpPDWAkmW/LDcwdzmrWez8wzm3G 6ATc9q2mngUTLLKpHZMh3ucS60Ih3vinZuo01DGvD6T4lp52V+llHU6AbL00S7fl40yb Z20Bm2OdU4qocuGZ3CH1yEK0gbodUlNEE+qOFQ92Mtv78eGEguGPXrc+9cslWdk80C2S 212+rk+y66B8WqR/dH2IDQcb3Z+01jCxkRGQ9ZJsWnppyWAsFfk6qLyPanO458YJbxbn hXdLcBOhFjYyRQD6uIuJ9ewh4rSht7lk6AguHfFzSMYHgSitep+herROVghcOmJg70E/ LI0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=+ESPc86/WR8zjQO6sLQzuGtCJWQp0GHtvc/0bwINti8=; b=A8ru0EVg2ZhobQV/3Bb7DeIfXdKLXgNLCNtj0O2t5tdDyNR16hIiG4APG7lyO9I/n2 ZM7DNljTL/UnnJSHyfF/7zt0F41f8xJvu4ELQDlO1pAr8mBV5hKO5Z3lVZDIuo7FCxqa wrz+c8pbfeDBvd+eVfh6UAjFW0R/2iJDgk7DRUVqY6hWt8UchC1SmZAMLpkF2a3mYOuV 1cy8IcTyRsEt8uEmqZRc/Jv/gw48C3K5nDxzHsn29ceXXtZL7RJUNg8Nw0K2CVXH/S4g uE1aCVy6WFsMoIElFX7Uyv923Oj0kfO+httBzqEKtcImt5BHLoIuLsuwaQ18bVlTc50G +h/A== X-Gm-Message-State: AOAM533LhkWNldbeRx+2vymb+Q8MoKDlgScZ44XA0zPqzR8Ft7xLJTAM +D2sbHGCZwTiao4aGt7JfEwczz8LLFPcnKrUMZ2Lng== X-Google-Smtp-Source: ABdhPJypgCH8IfPe2R8TbHORE195DoPYN1vP/sOAAUnmOfh4uWrncbqrxnflmO2jZEe1R5GUySlwHpsMHR9I5pnaZAk= X-Received: by 2002:a62:7ec4:0:b0:4a3:219b:7008 with SMTP id z187-20020a627ec4000000b004a3219b7008mr38300104pfc.3.1638813077797; Mon, 06 Dec 2021 09:51:17 -0800 (PST) MIME-Version: 1.0 References: <20211119040330.4013045-1-sathyanarayanan.kuppuswamy@linux.intel.com> <87pmqpjcef.ffs@tglx> <20211202222109.pcsgm2jska3obvmx@black.fi.intel.com> <87lf126010.ffs@tglx> <20211203234915.jw6kdd2qnfrionch@black.fi.intel.com> <2519e6b6-4f74-e2f8-c428-0fceb0e16472@intel.com> <20211204005427.ccinxlwwab3jsuct@black.fi.intel.com> <5bc40889-445d-5cac-3396-d39d53ee92c7@intel.com> In-Reply-To: From: Dan Williams Date: Mon, 6 Dec 2021 09:51:07 -0800 Message-ID: Subject: Re: [PATCH v2] x86: Skip WBINVD instruction for VM guest To: Dave Hansen Cc: "Kirill A. Shutemov" , Thomas Gleixner , Kuppuswamy Sathyanarayanan , Ingo Molnar , Borislav Petkov , Dave Hansen , X86 ML , "Rafael J . Wysocki" , "H . Peter Anvin" , Tony Luck , Andi Kleen , Kuppuswamy Sathyanarayanan , Linux Kernel Mailing List , Linux ACPI Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Mon, Dec 6, 2021 at 8:54 AM Dave Hansen wrote: > > On 12/6/21 8:39 AM, Dan Williams wrote: > >> But, the trick is that we need a contract. A contract requires a > >> "meeting of the minds" first. > > The WBINVD requirement in sleep states is about getting cache contents > > out to to power preserved domain before the CPU turns off. The bare > > metal host handles that requirement. The conversation that needs to be > > had is with the ACPI specification committee to clarify that virtual > > machines have no responsibility to flush caches. We can do that as a > > Code First proposal to the ACPI Specification Working Group. > > Sounds sane to me. So, we effectively go to the ACPI folks and say that > Linux isn't going to do WBINVD in virtualized environments any more. > That was effectively the approach that the first patch in this thread did: > > > https://lore.kernel.org/all/20211116005027.2929297-1-sathyanarayanan.kuppuswamy@linux.intel.com/ > > Right? Correct, my reviewed-by was based on that observation, and now we can close the loop by proposing the specification change.