From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D802C31E45 for ; Thu, 13 Jun 2019 22:01:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0190621537 for ; Thu, 13 Jun 2019 22:01:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728201AbfFMWBN (ORCPT ); Thu, 13 Jun 2019 18:01:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59552 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726316AbfFMWBN (ORCPT ); Thu, 13 Jun 2019 18:01:13 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8D0C4307D90D; Thu, 13 Jun 2019 22:01:12 +0000 (UTC) Received: from x1.home (ovpn-116-190.phx2.redhat.com [10.3.116.190]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0EB305C54A; Thu, 13 Jun 2019 22:01:09 +0000 (UTC) Date: Thu, 13 Jun 2019 16:01:09 -0600 From: Alex Williamson To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, KarimAllah Ahmed , linux-kernel@vger.kernel.org Subject: Re: [PATCH] PCI/IOV: Fix VF cfg_size Message-ID: <20190613160109.23e1747c@x1.home> In-Reply-To: <20190613212039.GL13533@google.com> References: <155966918965.10361.16228304474160813310.stgit@gimli.home> <20190604143617.0a226555@x1.home> <20190613212039.GL13533@google.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Thu, 13 Jun 2019 22:01:12 +0000 (UTC) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, 13 Jun 2019 16:20:39 -0500 Bjorn Helgaas wrote: > On Tue, Jun 04, 2019 at 02:36:17PM -0600, Alex Williamson wrote: > > On Tue, 04 Jun 2019 11:26:42 -0600 > > Alex Williamson wrote: > > > > > Commit 975bb8b4dc93 ("PCI/IOV: Use VF0 cached config space size for > > > other VFs") attempts to cache the config space size of VF0 to re-use > > > for all other VFs, but the cache is setup before the call to > > > pci_setup_device(), where we use set_pcie_port_type() to setup the > > > pcie_cap field on the struct pci_dev. Without pcie_cap configured, > > > pci_cfg_space_size() returns PCI_CFG_SPACE_SIZE for the size. VF0 > > > has a bypass through pci_cfg_space_size(), so its size is reported > > > correctly, but all subsequent VFs incorrectly report 256 bytes of > > > config space. > > > > > > Resolve by delaying pci_read_vf_config_common() until after > > > pci_setup_device(). > > > > > > Fixes: 975bb8b4dc93 ("PCI/IOV: Use VF0 cached config space size for other VFs") > > > Link: https://bugzilla.redhat.com/show_bug.cgi?id=1714978 > > > Cc: KarimAllah Ahmed > > > Signed-off-by: Alex Williamson > > > --- > > > drivers/pci/iov.c | 6 +++--- > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > > > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c > > > index 3aa115ed3a65..34b1f78f4d31 100644 > > > --- a/drivers/pci/iov.c > > > +++ b/drivers/pci/iov.c > > > @@ -161,13 +161,13 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id) > > > virtfn->is_virtfn = 1; > > > virtfn->physfn = pci_dev_get(dev); > > > > > > - if (id == 0) > > > - pci_read_vf_config_common(virtfn); > > > - > > > rc = pci_setup_device(virtfn); > > > if (rc) > > > goto failed1; > > > > > > + if (id == 0) > > > + pci_read_vf_config_common(virtfn); > > > + > > > virtfn->dev.parent = dev->dev.parent; > > > virtfn->multifunction = 0; > > > > Would it actually make more sense to revert 975bb8b4dc93 and just > > assume any is_virtfn device has PCI_CFG_SPACE_EXP_SIZE for cfg_size? > > Per the SR-IOV spec, VFs are required to implement a PCIe capability, > > which should imply 4K of config space. The reachability of that > > extended config space seems unnecessary to test if we assume that it > > has the same characteristics as the PF, which must be reachable if > > we're able to enable SR-IOV. Thoughts? Thanks, > > I like this idea. > > I first thought maybe we'd still be susceptible to the gotchas > described in the pci_cfg_space_size_ext() comment, i.e., we might not > have a way to generate extended config space accesses, or the device > might be behind a reverse Express bridge. > > But as you say, SR-IOV is an extended capability that must be located > at config offset 0x100 or greater, so the fact that we have a VF at > all means we must be able to reach it. Cool, I'll send a patch shortly. Thanks, Alex