From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rgcy23VbWzDq5d for ; Fri, 1 Jul 2016 10:40:08 +1000 (AEST) Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u610cOit139464 for ; Thu, 30 Jun 2016 20:40:06 -0400 Received: from e23smtp01.au.ibm.com (e23smtp01.au.ibm.com [202.81.31.143]) by mx0a-001b2d01.pphosted.com with ESMTP id 23v6yf7md7-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 30 Jun 2016 20:40:06 -0400 Received: from localhost by e23smtp01.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 1 Jul 2016 10:40:03 +1000 Received: from d23relay10.au.ibm.com (d23relay10.au.ibm.com [9.190.26.77]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id 729962CE8054 for ; Fri, 1 Jul 2016 10:40:01 +1000 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay10.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u610e19A8651258 for ; Fri, 1 Jul 2016 10:40:01 +1000 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u610e0YM014865 for ; Fri, 1 Jul 2016 10:40:01 +1000 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 In-Reply-To: <1467283993-3185-3-git-send-email-xyjxie@linux.vnet.ibm.com> Message-Id: <20160701003959.GB15147@gwshan> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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