Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751888AbdF2X1g (ORCPT ); Thu, 29 Jun 2017 19:27:36 -0400 Received: from mail-vk0-f68.google.com ([209.85.213.68]:33807 "EHLO mail-vk0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751701AbdF2X0q (ORCPT ); Thu, 29 Jun 2017 19:26:46 -0400 MIME-Version: 1.0 In-Reply-To: References: <20170316215057.452220163@linutronix.de> From: Yinghai Lu Date: Thu, 29 Jun 2017 16:26:44 -0700 X-Google-Sender-Auth: W5nh_Ta6YQ0KYcAj0O7izOX6YsY Message-ID: Subject: Re: [tip:x86/platform] x86/PCI/mmcfg: Switch to ECAM config mode if possible To: Stephane Eranian , "H. Peter Anvin" , Ingo Molnar , Peter Zijlstra , Borislav Petkov , Linux Kernel Mailing List , Thomas Gleixner , Bjorn Helgaas , Andi Kleen , Linus Torvalds , Matthew Wilcox , Ivan Kokshaysky Cc: "linux-tip-commits@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5318 Lines: 137 On Wed, Jun 28, 2017 at 11:45 PM, tip-bot for Thomas Gleixner wrote: > Commit-ID: b5b0f00c760b6e9673ab79b88ede2f3c7a039f74 > Gitweb: http://git.kernel.org/tip/b5b0f00c760b6e9673ab79b88ede2f3c7a039f74 > Author: Thomas Gleixner > AuthorDate: Thu, 16 Mar 2017 22:50:09 +0100 > Committer: Thomas Gleixner > CommitDate: Thu, 29 Jun 2017 08:41:54 +0200 > > x86/PCI/mmcfg: Switch to ECAM config mode if possible > > To allow lockless access to the whole PCI configuration space the mmconfig > based accessor functions need to be propagated to the pci_root_ops. > > Unfortunatly this cannot be done before the PCI subsystem initialization > happens even if mmconfig access is already available. The reason is that > some of the special platform PCI implementations must be able to overrule > that setting before further accesses happen. > > The earliest possible point is after x86_init.pci.init() has been run. This > is at a point in the boot process where nothing actually uses the PCI > devices so the accessor function pointers can be updated lockless w/o risk. > > The switch to full ECAM mode depends on the availability of mmconfig and > unchanged default accessors. > > Signed-off-by: Thomas Gleixner > Acked-by: Bjorn Helgaas > Cc: Andi Kleen > Cc: Peter Zijlstra > Cc: Stephane Eranian > Cc: Borislav Petkov > Cc: linux-pci@vger.kernel.org > Link: http://lkml.kernel.org/r/20170316215057.452220163@linutronix.de > Signed-off-by: Thomas Gleixner > --- > arch/x86/include/asm/pci_x86.h | 20 ++++++++++++-------- > arch/x86/pci/common.c | 16 ++++++++++++++++ > arch/x86/pci/legacy.c | 1 + > arch/x86/pci/mmconfig-shared.c | 30 ++++++++++++++++++++++++++++++ > arch/x86/pci/mmconfig_32.c | 8 ++++---- > arch/x86/pci/mmconfig_64.c | 8 ++++---- > 6 files changed, 67 insertions(+), 16 deletions(-) > > /* > + * Called after the last possible modification to raw_pci_[ext_]ops. > + * > + * Verify that root_pci_ops have not been overwritten by any implementation > + * of x86_init.pci.arch_init() and x86_init.pci.init(). > + * > + * If not, let the mmconfig code decide whether the ops can be switched > + * over to the ECAM accessor functions. > + */ > +void __init pcibios_select_ops(void) > +{ > + if (pci_root_ops.read != pci_read || pci_root_ops.write != pci_write) > + return; > + pci_mmcfg_select_ops(); > +} > + > +/* > * Called after each bus is probed, but before its children > * are examined. > */ > diff --git a/arch/x86/pci/legacy.c b/arch/x86/pci/legacy.c > index 1cb01ab..80ea40e 100644 > --- a/arch/x86/pci/legacy.c > +++ b/arch/x86/pci/legacy.c > @@ -65,6 +65,7 @@ static int __init pci_subsys_init(void) > } > } > > + pcibios_select_ops(); > pcibios_fixup_peer_bridges(); > x86_init.pci.init_irq(); > pcibios_init(); > diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c > index d1b47d5..6af6351 100644 > --- a/arch/x86/pci/mmconfig-shared.c > +++ b/arch/x86/pci/mmconfig-shared.c > @@ -816,3 +816,33 @@ int pci_mmconfig_delete(u16 seg, u8 start, u8 end) > > return -ENOENT; > } > + > +static int pci_ecam_read(struct pci_bus *bus, unsigned int devfn, int reg, > + int size, u32 *value) > +{ > + return pci_mmcfg_read(pci_domain_nr(bus), bus->number, devfn, reg, > + size, value); > +} > + > +static int pci_ecam_write(struct pci_bus *bus, unsigned int devfn, int reg, > + int size, u32 value) > +{ > + return pci_mmcfg_write(pci_domain_nr(bus), bus->number, devfn, reg, > + size, value); > +} > + > +void __init pci_mmcfg_select_ops(void) > +{ > + if (raw_pci_ext_ops != &pci_mmcfg) > + return; > + > + /* > + * The pointer to root_pci_ops has been handed in to ACPI already > + * and is already set in the busses. > + * > + * Switch the functions over to ECAM for all config space accesses. > + */ > + pci_root_ops.read = pci_ecam_read; > + pci_root_ops.write = pci_ecam_write; > + pr_info("PCI: Switch to ECAM configuration mode\n"); > +} Hi Thomas, Would this patch actually void the commit: commit a0ca9909609470ad779b9b9cc68ce96e975afff7 Author: Ivan Kokshaysky Date: Mon Jan 14 17:31:09 2008 -0500 PCI x86: always use conf1 to access config space below 256 bytes Thanks to Loic Prylli , who originally proposed this idea. Always using legacy configuration mechanism for the legacy config space and extended mechanism (mmconf) for the extended config space is a simple and very logical approach. It's supposed to resolve all known mmconf problems. It still allows per-device quirks (tweaking dev->cfg_size). It also allows to get rid of mmconf fallback code. Signed-off-by: Ivan Kokshaysky Signed-off-by: Matthew Wilcox Signed-off-by: Linus Torvalds