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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 8D31EC5DF60 for ; Tue, 5 Nov 2019 22:45:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D0872053B for ; Tue, 5 Nov 2019 22:45:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572993938; bh=qeOzdpBEuDiMpmOSAKfNlmAzdojPQjaJa658ujJW01Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=nLGKFXpE0yC3GQ1jkregkBPjxQ4+ev0I4RNsLnganG7UaVEapdNaRua2BePYthZMF e06UjrccwN2FqRk8dYaTXT7O7mk1oVMkZJd55yx4y7qdjECNCyt5zvz/VFw2+YipBU 4zlO0kldPPdSfEPXf+Wua4QgymClGbG3FEj5RQYI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729747AbfKEWph (ORCPT ); Tue, 5 Nov 2019 17:45:37 -0500 Received: from mail.kernel.org ([198.145.29.99]:43216 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728515AbfKEWph (ORCPT ); Tue, 5 Nov 2019 17:45:37 -0500 Received: from redsun51.ssa.fujisawa.hgst.com (unknown [199.255.47.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BCF032084D; Tue, 5 Nov 2019 22:45:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572993937; bh=qeOzdpBEuDiMpmOSAKfNlmAzdojPQjaJa658ujJW01Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ImC0mSOmC6vylLQ+gWsAKnmAveVApQHZv4sRNnxQ/v24djZWBSl1wvQ3F6h/0jNz/ fhOXV+aLrmo/Ltkw3sA4FoZx3I/jSjP/8bLVV0bTdGwpoks37GinbXtOBUbA3DCuT1 2jk+JDE7NTHOE3KZVA/Qv9Ds8S2cH3HDUnYhAZ+g= Date: Wed, 6 Nov 2019 07:45:29 +0900 From: Keith Busch To: "Derrick, Jonathan" Cc: "lorenzo.pieralisi@arm.com" , "helgaas@kernel.org" , "andrew.murray@arm.com" , "Paszkiewicz, Artur" , "Baldysiak, Pawel" , "Fugate, David" , "Shevchenko, Andriy" , "linux-pci@vger.kernel.org" , "Busch, Keith" Subject: Re: [PATCH 2/3] PCI: vmd: Expose VMD details from BIOS Message-ID: <20191105224529.GA1443@redsun51.ssa.fujisawa.hgst.com> References: <20191101215302.GA217821@google.com> <5c4521d26f45cfe01631d14c3d7edc9a10f99245.camel@intel.com> <20191104180700.GB26409@e121166-lin.cambridge.arm.com> <20191105101208.GA21113@e121166-lin.cambridge.arm.com> <5a87add6071259c45522001648b29c9e597ebd69.camel@intel.com> <20191105222247.GA890@redsun51.ssa.fujisawa.hgst.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Nov 05, 2019 at 10:38:05PM +0000, Derrick, Jonathan wrote: > On Wed, 2019-11-06 at 07:22 +0900, Keith Busch wrote: > > On Tue, Nov 05, 2019 at 09:32:07PM +0000, Derrick, Jonathan wrote: > > > Without this patch, a /dev/mem, resource0, or third-party driver could > > > overwrite these values if they don't also restore them on close/unbind. > > > I imagine a kexec user would also overwrite these values. > > > > Don't you have the same problem with the in-kernel driver? It > > looks like pci core will clear the PCI_IO_BASE config registers in > > pci_setup_bridge_io() because VMD doesn't provide an IORESOURCE_IO > > resource. If you reload the driver, it'll read the wrong values on the > > second probing. > > Is there a corner case I am missing with patch 3/3 that restores on > unload? Nothing wrong with that. I just hadn't read that far :/