From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756338Ab2BANCU (ORCPT ); Wed, 1 Feb 2012 08:02:20 -0500 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:48887 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754307Ab2BANCS (ORCPT ); Wed, 1 Feb 2012 08:02:18 -0500 Date: Wed, 1 Feb 2012 18:32:06 +0530 From: Vaidyanathan Srinivasan To: Ram Pai Cc: Jesse Barnes , Yinghai Lu , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [BUGFIX][PATCH] pci: check for 4k resource_size alignment in sriov_init Message-ID: <20120201130206.GD3510@dirshya.in.ibm.com> Reply-To: svaidy@linux.vnet.ibm.com References: <20120127191032.GA22999@dirshya.in.ibm.com> <20120130031845.GA2359@ram-ThinkPad-T61> <20120131174402.GA6172@dirshya.in.ibm.com> <20120201062145.GA11505@ram-ThinkPad-T61> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20120201062145.GA11505@ram-ThinkPad-T61> User-Agent: Mutt/1.5.21 (2010-09-15) x-cbid: 12020102-1618-0000-0000-000000AE0229 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Ram Pai [2012-02-01 14:21:45]: > On Tue, Jan 31, 2012 at 11:14:02PM +0530, Vaidyanathan Srinivasan wrote: > > * Ram Pai [2012-01-30 11:18:45]: > > > > > On Sat, Jan 28, 2012 at 12:40:32AM +0530, Vaidyanathan Srinivasan wrote: > > > > Hi Ram and Jesse, > > > > > > > > I found a trivial issue with page size alignment check on IBM POWER > > > > box with 64k base page size. In sriov_init(), changing the check from > > > > PAGE_SIZE (arch and config dependent) to HW_PAGE_SIZE (always 4k) was > > > > required to use one of the sriov adapter as PF since the > > > > resource_size() comes up as 0x8000 and PAGE_SIZE would be 0x10000 for > > > > pseries boxes. > > > > > > > > I think resource_size() could be less than SystemPageSize, but I would > > > > like your comments/ack/nack on any consequences of checking for only > > > > 4k alignment here in a system with larger base page size. > > > > > > As per the SRIOV specs, the resource has to be System page size aligned. > > > > > > PFs are required to support 4-KB, 8-KB, 64-KB, 256-KB, 1-MB, and 4-MB > > > page sizes. In your case if your adapter's PF is not supporting 64K page size > > > then I think it is not conforming to the PCI SRIOV spec. > > > > Hi Ram, > > > > Thanks for the pointer. I did some more experiments and found that > > the card does support 64k page size, but the PCI_SRIOV_SYS_PGSIZE was > > set to default 4k when we do the query and check resource_size(). > > > > You were correct, the resource_size() has to come up with 64k on 64k > > PAGE_SIZE system. We should not change that check. I was able to > > get a working solution by setting PCI_SRIOV_SYS_PGSIZE to 64k before > > we do the query. > > > > This was the case in the original code before you moved these to > > sriov_enable(). If it is ok to leave the SYS_PGSIZE setting in > > sriov_init(), then I have the following fix that works for me. > > > > Please review and let me know your comments. > > > > Thanks, > > Vaidy > > --- > > > > pci: set pci sriov page size before reading sriov bar > > > > For an SRIOV device, PCI_SRIOV_SYS_PGSIZE should be set before > > the PCI_SRIOV_BAR is queried. The sys pagesize defaults to 4k, > > so this change is required on powerpc box with 64k base page size. > > > > This is a regression caused due to moving SRIOV init to sriov_enable(). > > > > | commit afd24ece5c76af87f6fc477f2747b83a764f161c > > | Author: Ram Pai > > > > | PCI: delay configuration of SRIOV capability > > | The SRIOV capability, namely page size and total_vfs of a device are > > | configured during enumeration phase of the device. This can potentially > > | interfere with the PCI operations of the platform, if the IOV capability > > | of the device is not enabled. > > > > Signed-off-by: Vaidyanathan Srinivasan > > > > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c > > index 0321fa3..0dab5ec 100644 > > --- a/drivers/pci/iov.c > > +++ b/drivers/pci/iov.c > > @@ -347,8 +347,6 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn) > > return rc; > > } > > > > - pci_write_config_dword(dev, iov->pos + PCI_SRIOV_SYS_PGSIZE, iov->pgsz); > > - > > iov->ctrl |= PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE; > > pci_cfg_access_lock(dev); > > pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl); > > @@ -466,6 +464,7 @@ found: > > return -EIO; > > > > pgsz &= ~(pgsz - 1); > > + pci_write_config_dword(dev, pos + PCI_SRIOV_SYS_PGSIZE, pgsz); > > > > nres = 0; > > for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) { > > > ACK. I think it is better to revert afd24ece5c76af87f6fc477f2747b83a764f161c. Hi Ram, Thanks for the ack. But afd24ece5c76af87f6fc477f2747b83a764f161c has one more change of moving pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, total) to sriov_enable(). This change is required so that we set the PCI_SRIOV_NUM_VF only during sriov_enable. So we should not revert the entire commit, we can just add this change. --Vaidy