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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 E702FC43603 for ; Wed, 4 Dec 2019 19:56:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B8E882073B for ; Wed, 4 Dec 2019 19:56:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="lbhaO1dQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728117AbfLDT4P (ORCPT ); Wed, 4 Dec 2019 14:56:15 -0500 Received: from mail-il1-f177.google.com ([209.85.166.177]:41709 "EHLO mail-il1-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727887AbfLDT4P (ORCPT ); Wed, 4 Dec 2019 14:56:15 -0500 Received: by mail-il1-f177.google.com with SMTP id z90so672955ilc.8 for ; Wed, 04 Dec 2019 11:56:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=1Y5s64cDULUztNcj+XAj5kwGyOnu+jNjLT/oyzvuGnI=; b=lbhaO1dQlgHzGQ5/4HMIQNpdlZiHVoUDGDV3tjj+/pi9pCZkoep1cf8V5QgBeOuDIc toI/ovwS4rTeWE1+5kTjhxxL6kjb470G5qpiOx7GJiwRRr6VnK7pFMMvyeGZ35NguKoc ZUYtXiubBjwoKVFPdR+LKkSzD6rZPTo+nxA0wQPPlcAVH+nMhxUHeaitXbcgh/QZK0AY WnhjKU90RXxBnb3PtXqXI0cB8HPWPyhA19OAc1qwA9s0xDr/R+VedqHa6C8WpX2sS+Rc ioOvWq9xQCNBh9qS+xGfoOIkcnncMmOVcioOtRdojOpxJJwOmFY5Jbgl8UjtXOyrT5JU rtag== 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=1Y5s64cDULUztNcj+XAj5kwGyOnu+jNjLT/oyzvuGnI=; b=MuLCczEk9dtMZ17+AuMPRENDcsa4qbOFubXIq9KvXBH/3sCJG5bF23y6LCPQ5o7AuS QggltJ4vHnUJoJtXKAoV4AF6378q3RBFzyb/wy2u5nDfKcWYnRdhxC9szmJGEud2QI0E +LpRwBCE9E3L9kuuxnNzz+qnCfS2Hr2vkqCNSOJtRvoAylsVIsWbIyG2FUsee9HUqKEA 75eA8mTCQvjqN1lmJsxiBEuS3edhH/CJMNO1JKvvQohoBRSoT7ZyXU2fCTpLtRC6oCiP M/ontzBSEeFJR0XzHCv0Xr6GL1A4nYa9YO5WrUrm46OspVAjUC2xmCit4K/Cwgfz+75C IvJQ== X-Gm-Message-State: APjAAAXbugwvNQA/axhvPa9rDEegG2BDHxlDXvyfC3OE1UyV1L0PpWd5 8IYOEnpLatRgeUm63qv2DPOx+JEmgE5Ew6BT7913IIVwiaY= X-Google-Smtp-Source: APXvYqwcACr24vKI7KQDbUQ+bw+TFSeLsgeQxf8+wvOA5AzZx+sH5UELtEFDWXQ2Polwg3Dv76CvaUjj30dIjMIEWnY= X-Received: by 2002:a92:d609:: with SMTP id w9mr5538958ilm.46.1575489374145; Wed, 04 Dec 2019 11:56:14 -0800 (PST) MIME-Version: 1.0 References: <20191203004043.174977-1-matthewgarrett@google.com> In-Reply-To: From: Matthew Garrett Date: Wed, 4 Dec 2019 11:56:02 -0800 Message-ID: Subject: Re: [PATCH] [EFI,PCI] Allow disabling PCI busmastering on bridges during boot To: Andy Lutomirski Cc: linux-efi , Ard Biesheuvel , X86 ML , linux-pci , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Wed, Dec 4, 2019 at 11:50 AM Andy Lutomirski wrote: > Wouldn't it also be applicable in the much simpler case where the > firmware hands over control with no IOMMU configured but also with the > busmastering bit cleared. Does firmware do this? Does the kernel > currently configure the iOMMU before enabling busmastering? We already handle this case - the kernel doesn't activate busmastering until after it does IOMMU setup.