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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=unavailable 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 8CB59C65C22 for ; Fri, 2 Nov 2018 09:53:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DDED2081F for ; Fri, 2 Nov 2018 09:53:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5DDED2081F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alien8.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726252AbeKBS7l (ORCPT ); Fri, 2 Nov 2018 14:59:41 -0400 Received: from mail.skyhub.de ([5.9.137.197]:43018 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726008AbeKBS7l (ORCPT ); Fri, 2 Nov 2018 14:59:41 -0400 X-Virus-Scanned: Nedap ESD1 at mail.skyhub.de Received: from mail.skyhub.de ([127.0.0.1]) by localhost (blast.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id q6_VM_YTgKXV; Fri, 2 Nov 2018 10:53:04 +0100 (CET) Received: from zn.tnic (p200300EC2BCD3B00329C23FFFEA6A903.dip0.t-ipconnect.de [IPv6:2003:ec:2bcd:3b00:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 906E21EC02E6; Fri, 2 Nov 2018 10:53:04 +0100 (CET) Date: Fri, 2 Nov 2018 10:53:00 +0100 From: Borislav Petkov To: Bjorn Helgaas Cc: Jon Derrick , linux-pci@vger.kernel.org, Lorenzo Pieralisi , Keith Busch , "Rafael J. Wysocki" , Len Brown , Tony Luck , Tyler Baicar , Christoph Hellwig , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] PCI/AER: Option to leave System Error Interrupts as-is Message-ID: <20181102095300.GB14602@zn.tnic> References: <1540585146-31876-1-git-send-email-jonathan.derrick@intel.com> <20181029210651.GB13681@bhelgaas-glaptop.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181029210651.GB13681@bhelgaas-glaptop.roam.corp.google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 29, 2018 at 04:06:51PM -0500, Bjorn Helgaas wrote: > [+cc Rafael, Len, Tony, Borislav, Tyler, Christoph, linux-acpi, LKML] > > On Fri, Oct 26, 2018 at 02:19:04PM -0600, Jon Derrick wrote: > > Add a bit in pci_host_bridge to indicate to leave the System Error > > Interrupts as configured by the pre-boot environment. Propagate this to > > the AER driver which disables System Error Interrupts. This commit message should not explain what the patch does - that's obvious - but why it is doing it. > > Signed-off-by: Jon Derrick > > --- > > drivers/pci/pcie/aer.c | 7 +++++-- > > include/linux/pci.h | 3 +++ > > 2 files changed, 8 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c > > index 83180ed..6a4af63 100644 > > --- a/drivers/pci/pcie/aer.c > > +++ b/drivers/pci/pcie/aer.c > > @@ -1360,6 +1360,7 @@ static void set_downstream_devices_error_reporting(struct pci_dev *dev, > > static void aer_enable_rootport(struct aer_rpc *rpc) > > { > > struct pci_dev *pdev = rpc->rpd; > > + struct pci_host_bridge *host; > > int aer_pos; > > u16 reg16; > > u32 reg32; > > @@ -1369,8 +1370,10 @@ static void aer_enable_rootport(struct aer_rpc *rpc) > > pcie_capability_write_word(pdev, PCI_EXP_DEVSTA, reg16); > > > > /* Disable system error generation in response to error messages */ > > - pcie_capability_clear_word(pdev, PCI_EXP_RTCTL, > > - SYSTEM_ERROR_INTR_ON_MESG_MASK); > > + host = pci_find_host_bridge(pdev->bus); > > + if (!host->no_disable_sys_err) Double negation if (! .. ->no.. could simply be if (host->disable_sys_err... > > + pcie_capability_clear_word(pdev, PCI_EXP_RTCTL, > > + SYSTEM_ERROR_INTR_ON_MESG_MASK); > > If I squint hard enough this sort of makes sense, but it also makes me > confused about the normal APEI firmware-first model works. > > In the NON-firmare-first case, firmware isn't involved in handling AER > errors. The Linux AER driver fields an interrupt from a Root Port, > reads AER log registers, etc. > > In the normal APEI firmware-first case, when the hardware reports an > AER event, I think firmware gets control first, and *it* reads the AER > log registers, packages them up, and generates an interrupt to the OS, > which reads the packaged error state from the firmware via the HEST. > > If I understand this special Intel VMD firmware-first case correctly, > firmware gets control first, reads the AER log registers, and > synthesizes what looks to the OS like a normal AER interrupt. The Why? Why the faking? If firmware needs to get control, why doesn't it then *retain* control and report the error through HEST, like others do? AFAIUC, fw wants to do something underneath. What's wrong with making it a normal firmware-first case? -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.