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 3tTbWm0NPqzDsyK for ; Thu, 1 Dec 2016 10:01:39 +1100 (AEDT) Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id uAUMs8Gf135824 for ; Wed, 30 Nov 2016 18:01:36 -0500 Received: from e23smtp07.au.ibm.com (e23smtp07.au.ibm.com [202.81.31.140]) by mx0a-001b2d01.pphosted.com with ESMTP id 2724mx136f-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 30 Nov 2016 18:01:36 -0500 Received: from localhost by e23smtp07.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 1 Dec 2016 09:01:33 +1000 Received: from d23relay09.au.ibm.com (d23relay09.au.ibm.com [9.185.63.181]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id 1DBFD2CE805A for ; Thu, 1 Dec 2016 10:01:32 +1100 (EST) Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay09.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id uAUN1Wgk58589396 for ; Thu, 1 Dec 2016 10:01:32 +1100 Received: from d23av02.au.ibm.com (localhost [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id uAUN1VgO005565 for ; Thu, 1 Dec 2016 10:01:31 +1100 Date: Thu, 1 Dec 2016 10:02:54 +1100 From: Gavin Shan To: Bjorn Helgaas Cc: Gavin Shan , clsoto@us.ibm.com, linux-pci@vger.kernel.org, Bjorn Helgaas , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v4 3/7] PCI: Separate VF BAR updates from standard BAR updates Reply-To: Gavin Shan References: <20161129035218.21453.93986.stgit@bhelgaas-glaptop.roam.corp.google.com> <20161129041506.21453.18478.stgit@bhelgaas-glaptop.roam.corp.google.com> <20161129045546.GB20642@gwshan> <20161129144826.GB7285@bhelgaas-glaptop.roam.corp.google.com> <20161129232028.GA8143@gwshan> <20161130000605.GC7375@bhelgaas-glaptop.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20161130000605.GC7375@bhelgaas-glaptop.roam.corp.google.com> Message-Id: <20161130230254.GA10567@gwshan> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Nov 29, 2016 at 06:06:05PM -0600, Bjorn Helgaas wrote: >On Wed, Nov 30, 2016 at 10:20:28AM +1100, Gavin Shan wrote: >> On Tue, Nov 29, 2016 at 08:48:26AM -0600, Bjorn Helgaas wrote: >> >On Tue, Nov 29, 2016 at 03:55:46PM +1100, Gavin Shan wrote: >> >> On Mon, Nov 28, 2016 at 10:15:06PM -0600, Bjorn Helgaas wrote: >> >> >Previously pci_update_resource() used the same code path for updating >> >> >standard BARs and VF BARs in SR-IOV capabilities. >> >> > >> >> >Split the VF BAR update into a new pci_iov_update_resource() internal >> >> >interface, which makes it simpler to compute the BAR address (we can get >> >> >rid of pci_resource_bar() and pci_iov_resource_bar()). >> >> > >> >> >This patch: >> >> > >> >> > - Renames pci_update_resource() to pci_std_update_resource(), >> >> > - Adds pci_iov_update_resource(), >> >> > - Makes pci_update_resource() a wrapper that calls the appropriate one, >> >> > >> >> >No functional change intended. > >> >However, I don't think this code in pci_update_resource() is obviously >> >correct: >> > >> > new = region.start | (res->flags & PCI_REGION_FLAG_MASK); >> > >> >PCI_REGION_FLAG_MASK is 0xf. For memory BARs, bits 0-3 are read-only >> >property bits. For I/O BARs, bits 0-1 are read-only and bits 2-3 are >> >part of the address, so on the face of it, the above could corrupt two >> >bits of an I/O address. >> > >> >It's true that decode_bar() initializes flags correctly, using >> >PCI_BASE_ADDRESS_IO_MASK for I/O BARs and PCI_BASE_ADDRESS_MEM_MASK >> >for memory BARs, but it would take a little more digging to be sure >> >that we never set bits 2-3 of flags for an I/O resource elsewhere. >> > >> >> The BAR's property bits are probed from device-tree, not hardware >> on some platforms (e.g. pSeries). Also, there is only one (property) >> bit if it's a ROM BAR. So more check as below might be needed because >> the code (without the enhancement) should also work fine. > >Ah, right, I forgot about that. I didn't do enough digging :) > >> >How about this in pci_std_update_resource(): >> > >> > pcibios_resource_to_bus(dev->bus, ®ion, res); >> > new = region.start; >> > >> > if (res->flags & IORESOURCE_IO) { >> > mask = (u32)PCI_BASE_ADDRESS_IO_MASK; >> > new |= res->flags & ~PCI_BASE_ADDRESS_IO_MASK; >> > } else { >> > mask = (u32)PCI_BASE_ADDRESS_MEM_MASK; >> > new |= res->flags & ~PCI_BASE_ADDRESS_MEM_MASK; >> > } >> > >> >> if (res->flags & IORESOURCE_IO) { >> mask = (u32)PCI_BASE_ADDRESS_IO_MASK; >> new |= res->flags & ~PCI_BASE_ADDRESS_IO_MASK; >> } else if (resno < PCI_ROM_RESOURCE) { >> mask = (u32)PCI_BASE_ADDRESS_MEM_MASK; >> new |= res->flags & ~PCI_BASE_ADDRESS_MEM_MASK; >> } else if (resno == PCI_ROM_RESOURCE) { >> mask = ~((u32)IORESOURCE_ROM_ENABLE); >> new |= res->flags & IORESOURCE_ROM_ENABLE); >> } else { >> dev_warn(&dev->dev, "BAR#%d out of range\n", resno); >> return; >> } > >After this patch, the only thing we OR into a ROM BAR value is >PCI_ROM_ADDRESS_ENABLE, and that's done below, only if the ROM is >already enabled. > >I did update the ROM mask (to PCI_ROM_ADDRESS_MASK). I'm not 100% >sure about doing that -- it follows the spec, but it is a change from >what we've been doing before. I guess it should be safe because it >means we're checking fewer bits than before (only the top 21 bits for >ROMs, where we used check the top 28), so the only possible difference >is that we might not warn about "error updating" in some case where we >used to. > >I'm not really sure about the value of the "error updating" checks to >begin with, though I guess it does help us find broken devices that >put non-BARs where BARs are supposed to be. > Yeah, agree. Bjorn, I don't have more comments. please take your time to respin the series and maybe applied it. I really want to see the fixes can be in 4.10 if possible :-) Thanks, Gavin