From patchwork Fri Mar 2 21:36:39 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bjorn Helgaas X-Patchwork-Id: 10255711 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C43E56037D for ; Fri, 2 Mar 2018 21:36:43 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B19EF283F9 for ; Fri, 2 Mar 2018 21:36:43 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A60A628531; Fri, 2 Mar 2018 21:36:43 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F1F2F283F9 for ; Fri, 2 Mar 2018 21:36:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934117AbeCBVgl (ORCPT ); Fri, 2 Mar 2018 16:36:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:43626 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933995AbeCBVgl (ORCPT ); Fri, 2 Mar 2018 16:36:41 -0500 Received: from localhost (unknown [69.55.156.246]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 49A3621783; Fri, 2 Mar 2018 21:36:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 49A3621783 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=helgaas@kernel.org Date: Fri, 2 Mar 2018 15:36:39 -0600 From: Bjorn Helgaas To: KarimAllah Ahmed Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Bjorn Helgaas Subject: Re: [PATCH v3 1/2] PCI/IOV: Store more data about VFs into the SRIOV struct Message-ID: <20180302213639.GC202062@bhelgaas-glaptop.roam.corp.google.com> References: <1519939897-14596-1-git-send-email-karahmed@amazon.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1519939897-14596-1-git-send-email-karahmed@amazon.de> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Thu, Mar 01, 2018 at 10:31:36PM +0100, KarimAllah Ahmed wrote: > Store more data about PCI VFs into the SRIOV to avoid reading them from the > config space of all the PCI VFs. This is specially a useful optimization > when bringing up thousands of VFs. > > Cc: Bjorn Helgaas > Cc: linux-pci@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: KarimAllah Ahmed Applied to pci/virtualization for v4.17, thanks! I removed the pci_sriov.device field, which seemed to be unused, and tweaked a few other things, so make sure I didn't break anything. Here's what I have currently applied: commit e17b7b429b095200f93ad37c4efeb7a99b6fce3b Author: KarimAllah Ahmed Date: Thu Mar 1 22:31:36 2018 +0100 PCI/IOV: Use VF0 cached config registers for other VFs Cache some config data from VF0 and use it for all other VFs instead of reading it from the config space of each VF. We assume these items are the same across all associated VFs: Revision ID Class Code Subsystem Vendor ID Subsystem ID This is an optimization when enabling SR-IOV on a device with many VFs. Signed-off-by: KarimAllah Ahmed [bhelgaas: changelog, simplify comments, remove unused "device"] Signed-off-by: Bjorn Helgaas diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c index 677924ae0350..30bf8f706ed9 100644 --- a/drivers/pci/iov.c +++ b/drivers/pci/iov.c @@ -114,6 +114,29 @@ resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno) return dev->sriov->barsz[resno - PCI_IOV_RESOURCES]; } +static void pci_read_vf_config_common(struct pci_dev *virtfn) +{ + struct pci_dev *physfn = virtfn->physfn; + + /* + * Some config registers are the same across all associated VFs. + * Read them once from VF0 so we can skip reading them from the + * other VFs. + * + * PCIe r4.0, sec 9.3.4.1, technically doesn't require all VFs to + * have the same Revision ID and Subsystem ID, but we assume they + * do. + */ + pci_read_config_dword(virtfn, PCI_CLASS_REVISION, + &physfn->sriov->class); + pci_read_config_byte(virtfn, PCI_HEADER_TYPE, + &physfn->sriov->hdr_type); + pci_read_config_word(virtfn, PCI_SUBSYSTEM_VENDOR_ID, + &physfn->sriov->subsystem_vendor); + pci_read_config_word(virtfn, PCI_SUBSYSTEM_ID, + &physfn->sriov->subsystem_device); +} + int pci_iov_add_virtfn(struct pci_dev *dev, int id) { int i; @@ -136,13 +159,17 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id) virtfn->devfn = pci_iov_virtfn_devfn(dev, id); virtfn->vendor = dev->vendor; virtfn->device = iov->vf_device; + 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 failed0; + goto failed1; virtfn->dev.parent = dev->dev.parent; - virtfn->physfn = pci_dev_get(dev); - virtfn->is_virtfn = 1; virtfn->multifunction = 0; for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) { @@ -163,10 +190,10 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id) sprintf(buf, "virtfn%u", id); rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf); if (rc) - goto failed1; + goto failed2; rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn"); if (rc) - goto failed2; + goto failed3; kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE); @@ -174,11 +201,12 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id) return 0; -failed2: +failed3: sysfs_remove_link(&dev->dev.kobj, buf); +failed2: + pci_stop_and_remove_bus_device(virtfn); failed1: pci_dev_put(dev); - pci_stop_and_remove_bus_device(virtfn); failed0: virtfn_remove_bus(dev->bus, bus); failed: diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index fcd81911b127..db76933be859 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -271,6 +271,10 @@ struct pci_sriov { u16 driver_max_VFs; /* Max num VFs driver supports */ struct pci_dev *dev; /* Lowest numbered PF */ struct pci_dev *self; /* This PF */ + u32 class; /* VF class */ + u8 hdr_type; /* VF header type */ + u16 subsystem_vendor; /* VF subsystem vendor */ + u16 subsystem_device; /* VF subsystem device */ resource_size_t barsz[PCI_SRIOV_NUM_BARS]; /* VF BAR size */ bool drivers_autoprobe; /* Auto probing of VFs by driver */ }; diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index a1cddca37793..78deb950bda1 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1461,7 +1461,9 @@ int pci_setup_device(struct pci_dev *dev) struct pci_bus_region region; struct resource *res; - if (pci_read_config_byte(dev, PCI_HEADER_TYPE, &hdr_type)) + if (dev->is_virtfn) + hdr_type = dev->physfn->sriov->hdr_type; + else if (pci_read_config_byte(dev, PCI_HEADER_TYPE, &hdr_type)) return -EIO; dev->sysdata = dev->bus->sysdata; @@ -1484,7 +1486,10 @@ int pci_setup_device(struct pci_dev *dev) dev->bus->number, PCI_SLOT(dev->devfn), PCI_FUNC(dev->devfn)); - pci_read_config_dword(dev, PCI_CLASS_REVISION, &class); + if (dev->is_virtfn) + class = dev->physfn->sriov->class; + else + pci_read_config_dword(dev, PCI_CLASS_REVISION, &class); dev->revision = class & 0xff; dev->class = class >> 8; /* upper 3 bytes */ @@ -1524,8 +1529,13 @@ int pci_setup_device(struct pci_dev *dev) goto bad; pci_read_irq(dev); pci_read_bases(dev, 6, PCI_ROM_ADDRESS); - pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, &dev->subsystem_vendor); - pci_read_config_word(dev, PCI_SUBSYSTEM_ID, &dev->subsystem_device); + if (dev->is_virtfn) { + dev->subsystem_vendor = dev->physfn->sriov->subsystem_vendor; + dev->subsystem_device = dev->physfn->sriov->subsystem_device; + } else { + pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, &dev->subsystem_vendor); + pci_read_config_word(dev, PCI_SUBSYSTEM_ID, &dev->subsystem_device); + } /* * Do the ugly legacy mode stuff here rather than broken chip