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=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 EAF4EC07E85 for ; Tue, 11 Dec 2018 04:11:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A536020672 for ; Tue, 11 Dec 2018 04:11:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A536020672 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-pci-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730112AbeLKELY (ORCPT ); Mon, 10 Dec 2018 23:11:24 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43886 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727566AbeLKELY (ORCPT ); Mon, 10 Dec 2018 23:11:24 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4112458E2E; Tue, 11 Dec 2018 04:11:24 +0000 (UTC) Received: from redhat.com (ovpn-120-187.rdu2.redhat.com [10.10.120.187]) by smtp.corp.redhat.com (Postfix) with SMTP id DB3F6608F2; Tue, 11 Dec 2018 04:11:22 +0000 (UTC) Date: Mon, 10 Dec 2018 23:11:22 -0500 From: "Michael S. Tsirkin" To: xuyandong Cc: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , Yinghai Lu , Jesse Barnes , Bjorn Helgaas , "linux-pci@vger.kernel.org" Subject: Re: [PATCH] pci: avoid bridge feature re-probing on hotplug Message-ID: <20181210231038-mutt-send-email-mst@kernel.org> References: <20181211021617.24072-1-mst@redhat.com> <7CECC2DFC21538489F72729DF5EFB4D908AC796C@DGGEMM501-MBX.china.huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7CECC2DFC21538489F72729DF5EFB4D908AC796C@DGGEMM501-MBX.china.huawei.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 11 Dec 2018 04:11:24 +0000 (UTC) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Dec 11, 2018 at 02:45:44AM +0000, xuyandong wrote: > > > > -----Original Message----- > > From: Michael S. Tsirkin [mailto:mst@redhat.com] > > Sent: Tuesday, December 11, 2018 10:19 AM > > To: linux-kernel@vger.kernel.org > > Cc: xuyandong ; stable@vger.kernel.org; Yinghai > > Lu ; Jesse Barnes ; Bjorn > > Helgaas ; linux-pci@vger.kernel.org > > Subject: [PATCH] pci: avoid bridge feature re-probing on hotplug > > > > commit 1f82de10d6 ("PCI/x86: don't assume prefetchable ranges are > > 64bit") added probing of bridge support for 64 bit memory each time bridge is > > re-enumerated. > > > > Unfortunately this probing is destructive if any device behind the bridge is in > > use at this time. > > > > There's no real need to re-probe the bridge features as the regiters in question > > never change - detect that using the memory flag being set and skip the > > probing. > > Avoiding repeated calls to pci_bridge_check_ranges might be even nicer would > > be a bigger patch and probably not appropriate on stable. > > > > Reported-by: xuyandong > > Cc: stable@vger.kernel.org > > Cc: Yinghai Lu > > Cc: Jesse Barnes > > Signed-off-by: Michael S. Tsirkin > > Tested-by: xuyandong Bjorn could you queue this for this release? > > --- > > > > This issue has been reported on upstream Linux and Centos. > > > > drivers/pci/setup-bus.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index > > ed960436df5e..7ab42f76579e 100644 > > --- a/drivers/pci/setup-bus.c > > +++ b/drivers/pci/setup-bus.c > > @@ -741,6 +741,13 @@ static void pci_bridge_check_ranges(struct pci_bus > > *bus) > > struct resource *b_res; > > > > b_res = &bridge->resource[PCI_BRIDGE_RESOURCES]; > > + > > + /* Don't re-check after this was called once already: > > + * important since bridge might be in use. > > + */ > > + if (b_res[1].flags & IORESOURCE_MEM) > > + return; > > + > > b_res[1].flags |= IORESOURCE_MEM; > > > > pci_read_config_word(bridge, PCI_IO_BASE, &io); > > -- > > MST