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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 6A023C28CBC for ; Sat, 9 May 2020 19:08:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 49147208E4 for ; Sat, 9 May 2020 19:08:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589051333; bh=V7nflp6cNkG5QGevgXa5od/IvI2G15l1QxbDlrMhLNE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=TE2daM7zjYgX5AQDN3KEVetrfth1LitxuIZdQS/MCsFcAVt5k32SA9w3mNWJhghvO AFwKaRp2yEUb68KEx13S2DVvnETUuOCi6RYCkd09iLtMrv4IeT9LWDQKat9/A7q5M7 G9OwOeJTRLhIBD6h979zR0tNaeoowS7EMe8CR/oU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728144AbgEITIw (ORCPT ); Sat, 9 May 2020 15:08:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:50736 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727940AbgEITIw (ORCPT ); Sat, 9 May 2020 15:08:52 -0400 Received: from mail-wm1-f45.google.com (mail-wm1-f45.google.com [209.85.128.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 978D6208E4 for ; Sat, 9 May 2020 19:08:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589051331; bh=V7nflp6cNkG5QGevgXa5od/IvI2G15l1QxbDlrMhLNE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=JqHGviI5EBrhkQrotH2SE8ZgCg+bRnc6ualxWiI9Y5q6eQZCgI+ONSUoHkcODKpxK vU0OQ6ejhus2pyQ1BWw0OL0CRolUm+vDIzBOX+gI6wjAmU5wPXRXklfKSWJe5itgdk ysjrpk82zFiHOaWlRg+wC5pRv1fj6MHwWnHVBtW8= Received: by mail-wm1-f45.google.com with SMTP id y24so14309922wma.4 for ; Sat, 09 May 2020 12:08:51 -0700 (PDT) X-Gm-Message-State: AGi0PubTlr2B9eoKzSPsyGkHM9ZiC9pl6jXhDI4UGAFltYteSBYasRX6 dBtDbCgShj39jNgnUW6GnkB3CuniQcG8G6g7lmwn/w== X-Google-Smtp-Source: APiQypKdBb41feJIlpHU/i82pAmRbOrknH7DpSZcASb4cLU12jXUnMf20fF4zb9Mw9BgFp7S4XdzYly6PJe+7KB4DLI= X-Received: by 2002:a7b:c74d:: with SMTP id w13mr21726641wmk.36.1589051330110; Sat, 09 May 2020 12:08:50 -0700 (PDT) MIME-Version: 1.0 References: <20200505131602.633487962@linutronix.de> <20200505134058.272448010@linutronix.de> In-Reply-To: From: Andy Lutomirski Date: Sat, 9 May 2020 12:08:38 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch V4 part 1 02/36] x86/hw_breakpoint: Prevent data breakpoints on cpu_entry_area To: Lai Jiangshan Cc: Thomas Gleixner , LKML , X86 ML , "Paul E. McKenney" , Andy Lutomirski , Alexandre Chartre , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Steven Rostedt , Joel Fernandes , Boris Ostrovsky , Juergen Gross , Brian Gerst , Mathieu Desnoyers , Josh Poimboeuf , Will Deacon , "Peter Zijlstra (Intel)" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 9, 2020 at 2:23 AM Lai Jiangshan wrote: > > On Tue, May 5, 2020 at 10:15 PM Thomas Gleixner wrote: > > > > From: Andy Lutomirski > > > > A data breakpoint near the top of an IST stack will cause unresoverable > > recursion. A data breakpoint on the GDT, IDT, or TSS is terrifying. > > Prevent either of these from happening. > > > > What happen when a data breakpoint on the direct GDT (load_direct_gdt()) > and the debug IDT (load_debug_idt()) which are not considered in this patch? > I have no idea, and learning the answer may involve talking to the respective CPU vendors' microcode engineers. We should probably block those, too.