From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:48450 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727485AbeLKCSm (ORCPT ); Mon, 10 Dec 2018 21:18:42 -0500 Date: Mon, 10 Dec 2018 21:18:40 -0500 From: "Michael S. Tsirkin" 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 Message-ID: <20181211021617.24072-1-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: stable-owner@vger.kernel.org List-ID: 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 --- 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