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=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 3BF6AC433DB for ; Sun, 24 Jan 2021 19:01:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 050CE22CF6 for ; Sun, 24 Jan 2021 19:01:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726164AbhAXTBT (ORCPT ); Sun, 24 Jan 2021 14:01:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:37842 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726007AbhAXTBR (ORCPT ); Sun, 24 Jan 2021 14:01:17 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0056722CF6; Sun, 24 Jan 2021 19:00:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611514835; bh=zPRBShW+C0ECiUPZnF9QfuDDNrOfRrLUNkgjZgH+0GI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cTug8Bnl7TMWh1zuTK/qKJXwI4zjBhtmWGPT82eBlHuJXa4OMVrPcYPZLduEJ5YTj byUnGorQjLEybVW5KubWN8WDKMYUvKNtx9s7EP0r5LtjJPlHQjJEwrmY9pdklmIZUC /h1B3Ml5OV+csPfzsAZOIgL5IC10Mxz5U5f2l7hAFOTUYUlA+NcWHxiJzVuboF1AjK Orty+PlgOEHOrCl0yqDYAoCgll0X2h0zGQGJxhCl0JCYciHpQzx0N7XBDOX4zIlhkj /apzU8f04CrQo3xU1sExm27xvkLxPz/yvc9IOXOqxm/vRbiw2NNKxAVc+DceoZ/fYj PtnsLJFvXsp6Q== Date: Sun, 24 Jan 2021 21:00:32 +0200 From: Leon Romanovsky To: Alexander Duyck Cc: Bjorn Helgaas , Saeed Mahameed , Jason Gunthorpe , Jakub Kicinski , linux-pci , linux-rdma@vger.kernel.org, Netdev , Don Dutile , Alex Williamson , "David S . Miller" Subject: Re: [PATCH mlx5-next v4 1/4] PCI: Add sysfs callback to allow MSI-X table size change of SR-IOV VFs Message-ID: <20210124190032.GD5038@unreal> References: <20210124131119.558563-1-leon@kernel.org> <20210124131119.558563-2-leon@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Sun, Jan 24, 2021 at 08:47:44AM -0800, Alexander Duyck wrote: > On Sun, Jan 24, 2021 at 5:11 AM Leon Romanovsky wrote: > > > > From: Leon Romanovsky > > > > Extend PCI sysfs interface with a new callback that allows configure > > the number of MSI-X vectors for specific SR-IO VF. This is needed > > to optimize the performance of newly bound devices by allocating > > the number of vectors based on the administrator knowledge of targeted VM. > > > > This function is applicable for SR-IOV VF because such devices allocate > > their MSI-X table before they will run on the VMs and HW can't guess the > > right number of vectors, so the HW allocates them statically and equally. > > > > 1) The newly added /sys/bus/pci/devices/.../vfs_overlay/sriov_vf_msix_count > > file will be seen for the VFs and it is writable as long as a driver is not > > bounded to the VF. > > > > The values accepted are: > > * > 0 - this will be number reported by the VF's MSI-X capability > > * < 0 - not valid > > * = 0 - will reset to the device default value > > > > 2) In order to make management easy, provide new read-only sysfs file that > > returns a total number of possible to configure MSI-X vectors. > > > > cat /sys/bus/pci/devices/.../vfs_overlay/sriov_vf_total_msix > > = 0 - feature is not supported > > > 0 - total number of MSI-X vectors to consume by the VFs > > > > Signed-off-by: Leon Romanovsky > > --- > > Documentation/ABI/testing/sysfs-bus-pci | 32 +++++ > > drivers/pci/iov.c | 180 ++++++++++++++++++++++++ > > drivers/pci/msi.c | 47 +++++++ > > drivers/pci/pci.h | 4 + > > include/linux/pci.h | 10 ++ > > 5 files changed, 273 insertions(+) > > > > > > > + > > +static umode_t sriov_pf_attrs_are_visible(struct kobject *kobj, > > + struct attribute *a, int n) > > +{ > > + struct device *dev = kobj_to_dev(kobj); > > + struct pci_dev *pdev = to_pci_dev(dev); > > + > > + if (!pdev->msix_cap || !dev_is_pf(dev)) > > + return 0; > > + > > + return a->mode; > > +} > > + > > +static umode_t sriov_vf_attrs_are_visible(struct kobject *kobj, > > + struct attribute *a, int n) > > +{ > > + struct device *dev = kobj_to_dev(kobj); > > + struct pci_dev *pdev = to_pci_dev(dev); > > + > > + if (!pdev->msix_cap || dev_is_pf(dev)) > > + return 0; > > + > > + return a->mode; > > +} > > + > > Given the changes I don't see why we need to add the "visible" > functions. We are only registering this from the PF if there is a need > to make use of the interfaces, correct? If so we can just assume that > the interfaces should always be visible if they are requested. I added them to make extension of this vfs_overlay interface more easy, so we won't forget that current fields needs "msix_cap". Also I followed same style as other attribute_group which has .is_visible. > > Also you may want to look at placing a link to the VF folders in the > PF folder, although I suppose there are already links from the PF PCI > device to the VF PCI devices so maybe that isn't necessary. It just > takes a few extra steps to navigate between the two. We already have, I don't think that we need to add extra links, it will give nothing. [leonro@vm ~]$ ls -l /sys/bus/pci/devices/0000\:01\:00.0/ .... drwxr-xr-x 2 root root 0 Jan 24 14:02 vfs_overlay lrwxrwxrwx 1 root root 0 Jan 24 14:02 virtfn0 -> ../0000:01:00.1 lrwxrwxrwx 1 root root 0 Jan 24 14:02 virtfn1 -> ../0000:01:00.2 .... Thanks