From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dylanger Daly Subject: Re: [PATCH] Add Undervolt MSRs to wrmsr function. Date: Thu, 18 Apr 2019 10:19:34 +0100 Message-ID: References: <20190418085634.3629-1-dylanger@thegrail.co> <53b32c69-b0b4-5441-c8e2-299769eabf8f@citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============3823579359462117102==" Return-path: In-Reply-To: <53b32c69-b0b4-5441-c8e2-299769eabf8f@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" To: Andrew Cooper Cc: Dylanger Daly , xen-devel@lists.xenproject.org, Jan Beulich , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org --===============3823579359462117102== Content-Type: multipart/alternative; boundary="000000000000d20a3e0586ca80c5" --000000000000d20a3e0586ca80c5 Content-Type: text/plain; charset="UTF-8" No worries Andrew, it was my first patch, thank you for the response. It's based on Xen 4.8 Dom0 should be controlling it, but I wasn't aware of the Security implications. The scope isn't well documented: https://ressman.org/posts/2018-06-26-voltage-temperature-tdp-thinkpad/ More experimental as it worked with my Laptop. Thank you for your time On Thu, Apr 18, 2019, 10:09 AM Andrew Cooper wrote: > On 18/04/2019 09:56, Dylanger Daly wrote: > > Giving Laptop Users the ability to Undervolt and change Temp Throttle > Limits. > > > > Signed-off-by: Dylanger Daly > > Thankyou for the patch. Which version of Xen is it against? It is > fairly old, given that the function you patch has now moved to > arch/x86/pv/emul-priv-op.c. Furthermore, this is the legacy path, so > the functions this should be added to are guest_{rdmsr,wrmsr}() in > arch/x86/msr.c > > What entity is controlling this? > > Sadly, there are a number of issues. You open these MSRs up to > unprivileged domUs, and there is a mismatch between the vcpus/pcpus. > > What is the scope of these MSRs? I guess dom0 is going to write them on > all cores, but as dom0 gets scheduled around, this wont match up with > the pcpus across the host. > > ~Andrew > --000000000000d20a3e0586ca80c5 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

No worries Andrew, it was my first patch, thank you for t= he response.

It's based on= Xen 4.8

Dom0 should be = controlling it, but I wasn't aware of the Security implications.

<= div dir=3D"auto">

The scope isn't well docum= ented:

=C2=A0https://ressman.org/posts/2018-= 06-26-voltage-temperature-tdp-thinkpad/

More experimental as it worked with my Laptop.

Thank you for your time

On Thu, Apr 18, 2019, 10:09 AM Andrew Cooper <andrew.cooper3@citrix.com> wrote:

On 18/04/2019 09:56, Dylanger Daly wrote:<= br> > Giving Laptop Users the ability to Undervolt and change Temp Throttle = Limits.
>
> Signed-off-by: Dylanger Daly <dylanger@thegrail.co>

Thankyou for the patch.=C2=A0 Which version of Xen is it against?=C2=A0 It = is
fairly old, given that the function you patch has now moved to
arch/x86/pv/emul-priv-op.c.=C2=A0 Furthermore, this is the legacy path, so<= br> the functions this should be added to are guest_{rdmsr,wrmsr}() in
arch/x86/msr.c

What entity is controlling this?

Sadly, there are a number of issues.=C2=A0 You open these MSRs up to
unprivileged domUs, and there is a mismatch between the vcpus/pcpus.

What is the scope of these MSRs?=C2=A0 I guess dom0 is going to write them = on
all cores, but as dom0 gets scheduled around, this wont match up with
the pcpus across the host.

~Andrew

--000000000000d20a3e0586ca80c5-- --===============3823579359462117102== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVucHJvamVjdC5vcmcKaHR0cHM6Ly9saXN0 cy54ZW5wcm9qZWN0Lm9yZy9tYWlsbWFuL2xpc3RpbmZvL3hlbi1kZXZlbA== --===============3823579359462117102==-- 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=-3.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 32BB0C10F14 for ; Thu, 18 Apr 2019 10:07:34 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 004B52184B for ; Thu, 18 Apr 2019 10:07:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=thegrail.co header.i=@thegrail.co header.b="amsvcBOl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 004B52184B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=thegrail.co Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hH3wd-0001qK-0u; Thu, 18 Apr 2019 10:07:03 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hH3Ct-0006B0-NK for xen-devel@lists.xenproject.org; Thu, 18 Apr 2019 09:19:47 +0000 X-Inumbo-ID: 1bf516a4-61bb-11e9-92d7-bc764e045a96 Received: from mail-oi1-x242.google.com (unknown [2607:f8b0:4864:20::242]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTPS id 1bf516a4-61bb-11e9-92d7-bc764e045a96; Thu, 18 Apr 2019 09:19:46 +0000 (UTC) Received: by mail-oi1-x242.google.com with SMTP id i21so1054815oib.11 for ; Thu, 18 Apr 2019 02:19:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=thegrail.co; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=GEtFH23t0bP77aPVM0j2pSrZHyntjnDJQaUtXJ0lO9g=; b=amsvcBOlL6aGB1QjwV/M7wv8aAwxcvUmV78s+7p+sKDB1D9FqWXc/BHghnJGjIz5al opCNiifmjPQB0Fv7hx67HQ9nblsjUdGHQbJvmWQJheG6ofCcezoEBY5c6oiBZ6sSf5ya oAplUx2mtud6EZj0ZLXDa4Jp3PHbcSDWfc99U= 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=GEtFH23t0bP77aPVM0j2pSrZHyntjnDJQaUtXJ0lO9g=; b=SMQStAw8nOFfw3Ynl4MK2zsLb4c20ZKCvLafdF9eiOiIAZwDdA4cxNNW7HLNBb/TnP lWBw9J1FOFDh0MYD/RZE9b91k632DAOmm/Bb1Tsxp0YelCTmoK5d88fh79yMLvuDrSr1 NLgfTswNzyU8bvTA+eQt55dvnHJVfeihh19Suqh1FtK5lUn4HPOxPF/46HcIqVCr4c5d tsF0O/fCRZyANUFEMzxHYQfKPdm+QUaciaemVEskGp41NHM/rld6obNFwvzhBR7vASS9 pXHHikXeQJNYvq5isaQmPSHYtWTLLWfbKsR7Q3DsIleQGxw0MHwurs6xTEDljdgzYOhE kw/A== X-Gm-Message-State: APjAAAWYZo06/m8rpN26tu7GCfjmOV1nNukVCpm/7YTdU71FTltxdgFJ hRM7dHiVlhfmoV0/QIt1GYcOf7fdLG7Ck8VNonQjDw== X-Google-Smtp-Source: APXvYqxR02Q71iSmw47SnAlogqP1QrlyBrGI6yQrSsnkcNS7B2mk0Acb4HMSLBuD5qj8Ng3tUxGXKTRSzVxTm7sAWZo= X-Received: by 2002:aca:510d:: with SMTP id f13mr1275007oib.174.1555579186311; Thu, 18 Apr 2019 02:19:46 -0700 (PDT) MIME-Version: 1.0 References: <20190418085634.3629-1-dylanger@thegrail.co> <53b32c69-b0b4-5441-c8e2-299769eabf8f@citrix.com> In-Reply-To: <53b32c69-b0b4-5441-c8e2-299769eabf8f@citrix.com> From: Dylanger Daly Date: Thu, 18 Apr 2019 10:19:34 +0100 Message-ID: To: Andrew Cooper X-Mailman-Approved-At: Thu, 18 Apr 2019 10:07:01 +0000 Subject: Re: [Xen-devel] [PATCH] Add Undervolt MSRs to wrmsr function. X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Dylanger Daly , xen-devel@lists.xenproject.org, Jan Beulich , xen-devel@lists.xen.org Content-Type: multipart/mixed; boundary="===============7250815228890833043==" Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Message-ID: <20190418091934.bypVaFxXhEJt3MtTevr9l5IBJZ3dOX2Xw0GP9OP3S-A@z> --===============7250815228890833043== Content-Type: multipart/alternative; boundary="000000000000d20a3e0586ca80c5" --000000000000d20a3e0586ca80c5 Content-Type: text/plain; charset="UTF-8" No worries Andrew, it was my first patch, thank you for the response. It's based on Xen 4.8 Dom0 should be controlling it, but I wasn't aware of the Security implications. The scope isn't well documented: https://ressman.org/posts/2018-06-26-voltage-temperature-tdp-thinkpad/ More experimental as it worked with my Laptop. Thank you for your time On Thu, Apr 18, 2019, 10:09 AM Andrew Cooper wrote: > On 18/04/2019 09:56, Dylanger Daly wrote: > > Giving Laptop Users the ability to Undervolt and change Temp Throttle > Limits. > > > > Signed-off-by: Dylanger Daly > > Thankyou for the patch. Which version of Xen is it against? It is > fairly old, given that the function you patch has now moved to > arch/x86/pv/emul-priv-op.c. Furthermore, this is the legacy path, so > the functions this should be added to are guest_{rdmsr,wrmsr}() in > arch/x86/msr.c > > What entity is controlling this? > > Sadly, there are a number of issues. You open these MSRs up to > unprivileged domUs, and there is a mismatch between the vcpus/pcpus. > > What is the scope of these MSRs? I guess dom0 is going to write them on > all cores, but as dom0 gets scheduled around, this wont match up with > the pcpus across the host. > > ~Andrew > --000000000000d20a3e0586ca80c5 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable