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=-2.2 required=3.0 tests=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 6927BC432C0 for ; Wed, 27 Nov 2019 17:38:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 42F112071E for ; Wed, 27 Nov 2019 17:38:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727097AbfK0Riv (ORCPT ); Wed, 27 Nov 2019 12:38:51 -0500 Received: from ale.deltatee.com ([207.54.116.67]:57182 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726729AbfK0Riv (ORCPT ); Wed, 27 Nov 2019 12:38:51 -0500 Received: from s0106ac1f6bb1ecac.cg.shawcable.net ([70.73.163.230] helo=[192.168.11.155]) by ale.deltatee.com with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1ia1H3-0003xR-Id; Wed, 27 Nov 2019 10:38:46 -0700 To: James Sewart , linux-pci@vger.kernel.org Cc: Christoph Hellwig , Dmitry Safonov <0x7f454c46@gmail.com>, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Dmitry Safonov , Alex Williamson , Bjorn Helgaas References: <20191120193228.GA103670@google.com> <6A902F0D-FE98-4760-ADBB-4D5987D866BE@arista.com> <20191126173833.GA16069@infradead.org> <547214A9-9FD0-4DD5-80E1-1F5A467A0913@arista.com> From: Logan Gunthorpe Message-ID: <9c54c5dd-702c-a19b-38ba-55ab73b24729@deltatee.com> Date: Wed, 27 Nov 2019 10:38:42 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <547214A9-9FD0-4DD5-80E1-1F5A467A0913@arista.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 70.73.163.230 X-SA-Exim-Rcpt-To: helgaas@kernel.org, alex.williamson@redhat.com, dima@arista.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, 0x7f454c46@gmail.com, hch@infradead.org, linux-pci@vger.kernel.org, jamessewart@arista.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v3 1/2] PCI: Add parameter nr_devfns to pci_add_dma_alias X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-11-27 6:27 a.m., James Sewart wrote: > * This helper encodes an 8-bit devfn as a bit number in dma_alias_mask > * which is used to program permissible bus-devfn source addresses for DMA > @@ -5873,8 +5874,12 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode, > * cannot be left as a userspace activity). DMA aliases should therefore > * be configured via quirks, such as the PCI fixup header quirk. > */ > -void pci_add_dma_alias(struct pci_dev *dev, u8 devfn) > +void pci_add_dma_alias(struct pci_dev *dev, u8 devfn_from, int nr_devfns) > { > + int devfn_to = devfn_from + nr_devfns - 1; > + > + BUG_ON(nr_devfns < 1); Why not just make nr_devfns unsigned and do nothing if it's zero? It might also be worth checking that nr_devfns + devfn_from is less than U8_MAX... But I'd probably avoid the BUG_ON and just truncate it. Logan