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=-5.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 25E3BC433E4 for ; Tue, 14 Jul 2020 17:04:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1FDA22574 for ; Tue, 14 Jul 2020 17:04:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chrisdown.name header.i=@chrisdown.name header.b="UEFCCb05" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728878AbgGNREH (ORCPT ); Tue, 14 Jul 2020 13:04:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727028AbgGNREH (ORCPT ); Tue, 14 Jul 2020 13:04:07 -0400 Received: from mail-ed1-x542.google.com (mail-ed1-x542.google.com [IPv6:2a00:1450:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0FD6EC061755 for ; Tue, 14 Jul 2020 10:04:07 -0700 (PDT) Received: by mail-ed1-x542.google.com with SMTP id a1so12587343edt.10 for ; Tue, 14 Jul 2020 10:04:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chrisdown.name; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=KFocyH23qRUfHuNAbjxsTyMPH4beeiu9XE4QFHWyAsU=; b=UEFCCb05ivGRMSxff1MIVrrOWKYkYKnmDOjaxeD/gc6NeFfjIUhnUWe7BFpLf8DUiN c3KaXDoQohgs7Ku/boXdZjFk8UheQeecWydhFFfDztnkZ0qnVXRowE/tdm7pgD/EWFtQ 7Htzyv5uQZ9wm+kPhm/rSAJL/e7FB+YIMHAuU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=KFocyH23qRUfHuNAbjxsTyMPH4beeiu9XE4QFHWyAsU=; b=ULOmVBi+uEB9OcfT6+3zWARbY1iFebk2D265elBLcWSP51xcRnwsCazJjwGiCh8YAV XehcKXtwuO2ntFdf25NG5adzrhrxlXp8GoO30LqbpfaPXGQpB67ucxRCvTr7lDbqT1Pl 0OhNjcM0kIHFTQbd1JTZthaUWWRnlWfWoSTV6NwHr/5KxMjlCMkus5TCiH9R/+4BQNFf Qpk6PuEPG7jyTNe7aBTAqwyoKkGSUEgVywkE6JKj8VrKAb933ycAeJPGUEQiXiSnthjZ 2BYVl528BLmcNPed+rTGf5znoTNGPlZEW0V0eVhZq9zmcUT4E0AhiOqyPM3yi37J9nVe PFww== X-Gm-Message-State: AOAM5309c30SceNIhJFs8JoAZE6+deSvOtrXQwuaF+kPnLt3FMib2U7x 8O8Swnk2c6nNaSKi+Z47KADuFg== X-Google-Smtp-Source: ABdhPJzQbkAz024pvJLVQTMaT7MdAmwnd4M05q/p3mwtjZZSnguxYUfGXsoF3mXdKO6rJFd9RogiEw== X-Received: by 2002:a05:6402:3048:: with SMTP id bu8mr5617980edb.367.1594746245696; Tue, 14 Jul 2020 10:04:05 -0700 (PDT) Received: from localhost ([2620:10d:c093:400::5:6f85]) by smtp.gmail.com with ESMTPSA id y22sm15117932edl.84.2020.07.14.10.04.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Jul 2020 10:04:05 -0700 (PDT) Date: Tue, 14 Jul 2020 18:04:04 +0100 From: Chris Down To: Borislav Petkov Cc: linux-kernel@vger.kernel.org, sean.j.christopherson@intel.com, tony.luck@intel.com, torvalds@linux-foundation.org, x86@kernel.org, kernel-team@fb.com, Matthew Garrett , "Rafael J. Wysocki" , Len Brown , Srinivas Pandruvada , Jacob Pan Subject: Re: [PATCH -v2.1] x86/msr: Filter MSR writes Message-ID: <20200714170404.GE2080@chrisdown.name> References: <20200615063837.GA14668@zn.tnic> <20200714121955.GA2080@chrisdown.name> <20200714154728.GA3101@nazgul.tnic> <20200714160448.GC2080@chrisdown.name> <20200714165621.GA3622@nazgul.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200714165621.GA3622@nazgul.tnic> User-Agent: Mutt/1.14.6 (2020-07-11) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Borislav Petkov writes: >On Tue, Jul 14, 2020 at 05:04:48PM +0100, Chris Down wrote: >> Since the issue involves DPTF which is only supported via binary blobs, I >> can't say for certain what the issue is. As I understand it, when the >> throttling behaviour isn't explicitly configured by the OS kernel, the >> default policy is extremely overeager. Matthew also had a look at it[0], but >> I don't know if anything eventually happened there. I've cc'ed him. >> >> Either way, again, this isn't really the point. :-) The point is that there >> _are_ currently widespread cases involving poking MSRs from userspace, >> however sacrilegious or ugly (which I agree with!), and while people should >> be told about that, it's excessive to have the potential to take up 80% of >> kmsg in the default configuration. It doesn't take thousands of messages to >> get the message across, that's what a custom printk ratelimit is for. > >Ok, feel free to suggest a fix, better yet send a patch. Otherwise, >you'd have to wait for my vacation to end first. :-) Sure thing, I'll send a patch tomorrow, then. :-)