From patchwork Thu Jun 9 18:20:16 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bjorn Helgaas X-Patchwork-Id: 9167705 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 8A663604DB for ; Thu, 9 Jun 2016 18:22:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7E9CF2835A for ; Thu, 9 Jun 2016 18:22:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6CE832835B; Thu, 9 Jun 2016 18:22:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 13056281F9 for ; Thu, 9 Jun 2016 18:22:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932909AbcFISUX (ORCPT ); Thu, 9 Jun 2016 14:20:23 -0400 Received: from mail.kernel.org ([198.145.29.136]:58822 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932380AbcFISUU (ORCPT ); Thu, 9 Jun 2016 14:20:20 -0400 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BEAB5202FE; Thu, 9 Jun 2016 18:20:18 +0000 (UTC) Received: from localhost (173-27-161-33.client.mchsi.com [173.27.161.33]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C43E320380; Thu, 9 Jun 2016 18:20:17 +0000 (UTC) Subject: [PATCH v1 1/3] PCI: Ignore write combining when mapping I/O port space To: Yinghai Lu , Benjamin Herrenschmidt , Michal Simek , Paul Mackerras , Michael Ellerman From: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Date: Thu, 09 Jun 2016 13:20:16 -0500 Message-ID: <20160609182016.13455.78148.stgit@bhelgaas-glaptop2.roam.corp.google.com> In-Reply-To: <20160609181102.13455.33593.stgit@bhelgaas-glaptop2.roam.corp.google.com> References: <20160609181102.13455.33593.stgit@bhelgaas-glaptop2.roam.corp.google.com> User-Agent: StGit/0.16 MIME-Version: 1.0 X-Virus-Scanned: ClamAV using ClamSMTP Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP PCI exposes files like /proc/bus/pci/00/00.0 in procfs. These files support operations like this: ioctl(fd, PCIIOC_MMAP_IS_IO); # request I/O port space ioctl(fd, PCIIOC_WRITE_COMBINE, 1); # request write-combining mmap(fd, ...) Write combining is useful on PCI memory space, but I don't think it makes sense on PCI I/O port space. We *could* change proc_bus_pci_ioctl() to make it impossible to set mmap_state == pci_mmap_io and write_combine at the same time, but that would break the following sequence, which is currently legal: mmap(fd, ...) # default is I/O, non-combining ioctl(fd, PCIIOC_WRITE_COMBINE, 1); # request write-combining ioctl(fd, PCIIOC_MMAP_IS_MEM); # request memory space mmap(fd, ...) Ignore the write-combining flag when mapping I/O port space. This patch should have no functional effect, based on this analysis of all implementations of pci_mmap_page_range(): - ia64 mips parisc sh unicore32 x86 do not support mapping of I/O port space at all. - arm cris microblaze mn10300 sparc xtensa support mapping of I/O port space, but ignore the write_combine argument to pci_mmap_page_range(). - powerpc supports mapping of I/O port space and uses write_combine, and it disables write combining for I/O port space in __pci_mmap_set_pgprot(). This patch makes it possible to remove __pci_mmap_set_pgprot() from powerpc, which simplifies that path. Signed-off-by: Bjorn Helgaas --- drivers/pci/proc.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index 3f155e7..2408abe 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -231,7 +231,7 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma) { struct pci_dev *dev = PDE_DATA(file_inode(file)); struct pci_filp_private *fpriv = file->private_data; - int i, ret; + int i, ret, write_combine; if (!capable(CAP_SYS_RAWIO)) return -EPERM; @@ -245,9 +245,12 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma) if (i >= PCI_ROM_RESOURCE) return -ENODEV; + if (fpriv->mmap_state == pci_mmap_mem) + write_combine = fpriv->write_combine; + else + write_combine = 0; ret = pci_mmap_page_range(dev, vma, - fpriv->mmap_state, - fpriv->write_combine); + fpriv->mmap_state, write_combine); if (ret < 0) return ret;