From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752021AbcGAAkL (ORCPT ); Thu, 30 Jun 2016 20:40:11 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:60081 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751665AbcGAAkI (ORCPT ); Thu, 30 Jun 2016 20:40:08 -0400 X-IBM-Helo: d23dlp02.au.ibm.com X-IBM-MailFrom: gwshan@linux.vnet.ibm.com X-IBM-RcptTo: linux-doc@vger.kernel.org;linux-kernel@vger.kernel.org;linux-pci@vger.kernel.org Date: Fri, 1 Jul 2016 10:39:59 +1000 From: Gavin Shan To: Yongji Xie Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, bhelgaas@google.com, alex.williamson@redhat.com, aik@ozlabs.ru, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, corbet@lwn.net, warrier@linux.vnet.ibm.com, zhong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, gwshan@linux.vnet.ibm.com Subject: Re: [PATCH v3 2/7] PCI: Ignore enforced alignment to VF BARs Reply-To: Gavin Shan References: <1467283993-3185-1-git-send-email-xyjxie@linux.vnet.ibm.com> <1467283993-3185-3-git-send-email-xyjxie@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1467283993-3185-3-git-send-email-xyjxie@linux.vnet.ibm.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16070100-0004-0000-0000-000001753397 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16070100-0005-0000-0000-0000082F3DEB Message-Id: <20160701003959.GB15147@gwshan> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-06-30_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1607010004 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 30, 2016 at 06:53:08PM +0800, Yongji Xie wrote: >VF BARs are read-only zeroes according to SRIOV spec, >the normal way(writing BARs) of allocating resources wouldn't >be applied to VFs. The VFs' resources would be allocated >when we enable SR-IOV capability. So we should not try to >reassign alignment after we enable VFs. It's meaningless >and will release the allocated resources which leads to a bug. > >Signed-off-by: Yongji Xie >--- > drivers/pci/pci.c | 4 ++++ > 1 file changed, 4 insertions(+) > >diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >index be8f72c..6ae02de 100644 >--- a/drivers/pci/pci.c >+++ b/drivers/pci/pci.c >@@ -4822,6 +4822,10 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev) > resource_size_t align, size; > u16 command; > >+ /* We should never try to reassign VF's alignment */ >+ if (dev->is_virtfn) >+ return; >+ Yongji, I think it's correct to ignore VF's BARs. Another concern is: it's safe to apply alignment to PF's IOV BARs? Lets have an extreme example here: one PF has 16 VFs; each VF has only one 1KB. It means the only PF IOV BAR is 16KB. I don't see how it works after expanding it to 64KB which is the page size. It might be not a problem on PowerNV platform, but potentially a issue on x86? > /* check if specified PCI is target device to reassign */ > align = pci_specified_resource_alignment(dev); > if (!align) Thanks, Gavin