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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 13CB1C433DF for ; Mon, 25 May 2020 18:08:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C77982071C for ; Mon, 25 May 2020 18:08:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="lqW+siR8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389782AbgEYSIk (ORCPT ); Mon, 25 May 2020 14:08:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52444 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388621AbgEYSIj (ORCPT ); Mon, 25 May 2020 14:08:39 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BCC08C061A0E for ; Mon, 25 May 2020 11:08:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=KtQ2SC4NpHGImf+Tkc9R2teElcvTerbBEl4X1UzaM28=; b=lqW+siR8qtiAMM7Ddod74VaBie aKsujkrzo3JVXxk/qIICnnccnJVJQt884GIWER0zPUzXJx2nqGRAaNsxMYV8Sq6Q/SEEGo0XkPDGZ /EJvlWvTNo1OW7TwjorFNCsMZnnwVc0WmjxVSUXHy8V1ZyVlr8uQ7YU4BrKmAF9keKI60F6cjpSNg an2IerjCCfGD+L39XIeikvdlcQdIiZOWtxTy40xrRZxC6jNg7FnMWiSLlWJA/aDKrheGokOqDoKtm SkSbxJdQZexIBIGyFAH6W4D0YCbhbsX5YwUmOyZ60cOtstxHtc8GrwuxBawUvvZepEO7UwJX52gKD MuSgxKyQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jdHWe-0004PD-Vv; Mon, 25 May 2020 18:08:37 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 6D698300478; Mon, 25 May 2020 20:08:34 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5847720BD4F43; Mon, 25 May 2020 20:08:34 +0200 (CEST) Date: Mon, 25 May 2020 20:08:34 +0200 From: Peter Zijlstra To: Andy Lutomirski Cc: Rasmus Villemoes , Andy Lutomirski , Thomas Gleixner , LKML , X86 ML Subject: Re: [RFC][PATCH 0/4] x86/entry: disallow #DB more Message-ID: <20200525180834.GF317569@hirez.programming.kicks-ass.net> References: <20200525110101.GG325303@hirez.programming.kicks-ass.net> <2E6DBDE0-FEEA-467F-A380-4ED736B6C912@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2E6DBDE0-FEEA-467F-A380-4ED736B6C912@amacapital.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 25, 2020 at 10:19:08AM -0700, Andy Lutomirski wrote: > How about adding it to cpu_tlbstate? A lot of NMIs are going to read > that anyway to check CR3. That might work I suppose; we're really pushing the name of it though. Also, that's PTI specific IIRC, and we're getting to the point where a significant number of CPUs no longer need that, right? > And blaming KVM is a bit misplaced. This isn’t KVM’s fault — it’s > Intel’s. VT-x has two modes: DR access exits and DR access doesn’t > exit. There’s no shadow mode. It's virt, I can't be arsed to care, whoever misdesigned it. We already have debugreg pvops, they can do shadow there.