From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f179.google.com ([209.85.213.179]:37486 "EHLO mail-ig0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753079AbbH0R2B (ORCPT ); Thu, 27 Aug 2015 13:28:01 -0400 Received: by igui7 with SMTP id i7so41568613igu.0 for ; Thu, 27 Aug 2015 10:28:00 -0700 (PDT) Date: Thu, 27 Aug 2015 12:27:53 -0500 From: Bjorn Helgaas To: Wei Yang Cc: linux-pci@vger.kernel.org, Alex Williamson Subject: Re: [PATCH v2] PCI: Don't update VF's BAR Message-ID: <20150827172753.GA27056@google.com> References: <20150714221511.GM24416@google.com> <1438159978-32285-1-git-send-email-weiyang@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1438159978-32285-1-git-send-email-weiyang@linux.vnet.ibm.com> Sender: linux-pci-owner@vger.kernel.org List-ID: [+cc Alex] On Wed, Jul 29, 2015 at 04:52:58PM +0800, Wei Yang wrote: > VF BARs are RO zero, so updating VF BARs will not take any effect. > See the SR-IOV spec r1.1, sec 3.4.1.11. > > Also this patch adds a warning in pci_update_resource() in case someone > really tries to update it. > > Signed-off-by: Wei Yang I applied this with some whitespace and changelog fixes to pci-4.4/virtualization for v4.4, thanks! I will rebase this branch v4.3-rc1 or later. You mentioned the justification (avoids "error updating" messages) on the mailing list. It helps me out if you include that in the changelog, but I added it for you. Bjorn commit fa47e4466c567b43bcf8e152a4425277b6d033d9 Author: Wei Yang Date: Wed Jul 29 16:52:58 2015 +0800 PCI: Don't try to restore VF BARs VF BARs are read-only zero, so updating VF BARs will not have any effect. See the SR-IOV spec r1.1, sec 3.4.1.11. Don't update VF BARs in pci_restore_bars(). This avoids spurious "BAR %d: error updating" messages that we see when doing vfio pass-through after 6eb7018705de ("vfio-pci: Move idle devices to D3hot power state"). [bhelgaas: changelog, fix whitespace] Signed-off-by: Wei Yang Signed-off-by: Bjorn Helgaas diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 0008c95..1a682f8 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -473,7 +473,7 @@ int pci_wait_for_pending(struct pci_dev *dev, int pos, u16 mask) } /** - * pci_restore_bars - restore a devices BAR values (e.g. after wake-up) + * pci_restore_bars - restore a device's BAR values (e.g. after wake-up) * @dev: PCI device to have its BARs restored * * Restore the BAR values for a given device, so as to make it @@ -483,6 +483,10 @@ static void pci_restore_bars(struct pci_dev *dev) { int i; + /* Per SR-IOV spec 3.4.1.11, VF BARs are RO zero */ + if (dev->is_virtfn) + return; + for (i = 0; i < PCI_BRIDGE_RESOURCES; i++) pci_update_resource(dev, i); } diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c index 232f925..152de5c 100644 --- a/drivers/pci/setup-res.c +++ b/drivers/pci/setup-res.c @@ -36,6 +36,11 @@ void pci_update_resource(struct pci_dev *dev, int resno) enum pci_bar_type type; struct resource *res = dev->resource + resno; + if (dev->is_virtfn) { + dev_warn(&dev->dev, "can't update VF BAR%d\n", resno); + return; + } + /* * Ignore resources for unimplemented BARs and unused resource slots * for 64 bit BARs.