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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 A856AC433B4 for ; Fri, 14 May 2021 09:21:50 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 16176613B5 for ; Fri, 14 May 2021 09:21:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 16176613B5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=iPAMrKsONxYyqdU68b9ywX7FqOumSNexcZaOK7QhA+4=; b=QHWHZbNihd0alvBXiCv1q3WkE zZAuhqxThzfMkqxnpxqlMUp2Ws2Qfgjc61V37s+/n3xKfvBV8GYKFzJ8iYFxo8UQclnI/D2Hfn808 q9VDsFRRQU4I6VTSfWMzXvIP94vM2c5rEbmW7ceMwBfq74446ruNLpYEcGXnA5jNHNARGgFb+4AH9 asX03NMeOw7JnKwzgrLIz+HCDG0Ihn+MxQ/0/OFf7s+L9RzUtI6q8wroOtlpq7E6talPmVXhF+va6 fYJdn9plyRVEscdNd0NbztRkoCp/wBo9dXr+Vd4bSb0bZn3HXWlGN6KWUCJPAkCMXRj4rTV7yJVMx GFk1ekLyw==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lhTzF-007brM-D2; Fri, 14 May 2021 09:20:01 +0000 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lhTzC-007bqz-Te for linux-arm-kernel@desiato.infradead.org; Fri, 14 May 2021 09:19:59 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=GBfYpRrVp/su1W55D/VNtyi25FDNzRIxc4h1UvEFnzU=; b=eDdvv5exyjgUKKLHhpPEkd2noW z680j0PFDtUW95Gm6MeBDDfSicp2QQURMcQRwgSEsLf2w9+BmKBZJAYN3DGuit1O/dJH0BphGto52 iou/5yKrpSk5POGjZMaUofhbx9lYIj3uKYsiIuP7BsDHqPUCnDbDXC4slI2h/+RUyDqH46MaFYYhJ OLxZNbM0nep+CFXP+8wPhcBBLVQ+QDq08R9PaR7zQ4/8m6O0QUTCNEs16Fd8rvGxymT0qKii3WiSo EyyQFwBXKm7o5yGEMhOPVhkFlk1ApR9A1yskOKIyTQBdZmYG5nwj/b5EvVP8xmv1qUCyODLhIvy8d puGH33+Q==; Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lhTz9-00Bqwm-LP for linux-arm-kernel@lists.infradead.org; Fri, 14 May 2021 09:19:57 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F09BA1480; Fri, 14 May 2021 02:19:51 -0700 (PDT) Received: from lpieralisi (e121166-lin.cambridge.arm.com [10.1.196.255]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C13FB3F719; Fri, 14 May 2021 02:19:48 -0700 (PDT) Date: Fri, 14 May 2021 10:19:43 +0100 From: Lorenzo Pieralisi To: Boqun Feng Cc: Mike Rapoport , Bjorn Helgaas , Arnd Bergmann , Marc Zyngier , Russell King , Andrew Lunn , Sebastian Hesselbarth , Gregory Clement , Catalin Marinas , Will Deacon , Thomas Bogendoerfer , Rob Herring , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , Thomas Petazzoni , Robin Murphy , Thomas Gleixner , Jon Derrick , Sunil Muthuswamy , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-pci@vger.kernel.org, linux-hyperv@vger.kernel.org Subject: Re: [RFC v2 1/7] PCI: Introduce pci_host_bridge::domain_nr Message-ID: <20210514091943.GA13309@lpieralisi> References: <20210503144635.2297386-1-boqun.feng@gmail.com> <20210503144635.2297386-2-boqun.feng@gmail.com> <20210506105245.GA26351@lpieralisi> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210514_021955_820270_13222F2F X-CRM114-Status: GOOD ( 39.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, May 10, 2021 at 09:44:29PM +0800, Boqun Feng wrote: > [Copy Rob] > > On Thu, May 06, 2021 at 11:52:45AM +0100, Lorenzo Pieralisi wrote: > > On Tue, May 04, 2021 at 08:16:30AM +0300, Mike Rapoport wrote: > > > On Mon, May 03, 2021 at 10:46:29PM +0800, Boqun Feng wrote: > > > > Currently we retrieve the PCI domain number of the host bridge from the > > > > bus sysdata (or pci_config_window if PCI_DOMAINS_GENERIC=y). Actually > > > > we have the information at PCI host bridge probing time, and it makes > > > > sense that we store it into pci_host_bridge. One benefit of doing so is > > > > the requirement for supporting PCI on Hyper-V for ARM64, because the > > > > host bridge of Hyper-V doesnt' have pci_config_window, whereas ARM64 is > > > > a PCI_DOMAINS_GENERIC=y arch, so we cannot retrieve the PCI domain > > > > number from pci_config_window on ARM64 Hyper-V guest. > > > > > > > > As the preparation for ARM64 Hyper-V PCI support, we introduce the > > > > domain_nr in pci_host_bridge, and set it properly at probing time, then > > > > for PCI_DOMAINS_GENERIC=y archs, bus domain numbers are set by the > > > > bridge domain_nr. > > > > > > > > Signed-off-by: Boqun Feng > > > > --- > > > > arch/arm/kernel/bios32.c | 2 ++ > > > > arch/arm/mach-dove/pcie.c | 2 ++ > > > > arch/arm/mach-mv78xx0/pcie.c | 2 ++ > > > > arch/arm/mach-orion5x/pci.c | 2 ++ > > > > arch/arm64/kernel/pci.c | 3 +-- > > > > arch/mips/pci/pci-legacy.c | 2 ++ > > > > arch/mips/pci/pci-xtalk-bridge.c | 2 ++ > > > > drivers/pci/controller/pci-ftpci100.c | 2 ++ > > > > drivers/pci/controller/pci-mvebu.c | 2 ++ > > > > drivers/pci/pci.c | 4 ++-- > > > > drivers/pci/probe.c | 7 ++++++- > > > > include/linux/pci.h | 11 ++++++++--- > > > > 12 files changed, 33 insertions(+), 8 deletions(-) > > > > > > > > diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c > > > > index e7ef2b5bea9c..4942cd681e41 100644 > > > > --- a/arch/arm/kernel/bios32.c > > > > +++ b/arch/arm/kernel/bios32.c > > > > @@ -471,6 +471,8 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw, > > > > bridge->sysdata = sys; > > > > bridge->busnr = sys->busnr; > > > > bridge->ops = hw->ops; > > > > + if (IS_ENABLED(CONFIG_PCI_DOMAINS_GENERIC)) > > > > + bridge->domain_nr = pci_bus_find_domain_nr(sys, parent); > > > > > > > > ret = pci_scan_root_bus_bridge(bridge); > > > > } > > > > diff --git a/arch/arm/mach-dove/pcie.c b/arch/arm/mach-dove/pcie.c > > > > index ee91ac6b5ebf..92eb8484b49b 100644 > > > > --- a/arch/arm/mach-dove/pcie.c > > > > +++ b/arch/arm/mach-dove/pcie.c > > > > @@ -167,6 +167,8 @@ dove_pcie_scan_bus(int nr, struct pci_host_bridge *bridge) > > > > bridge->sysdata = sys; > > > > bridge->busnr = sys->busnr; > > > > bridge->ops = &pcie_ops; > > > > + if (IS_ENABLED(CONFIG_PCI_DOMAINS_GENERIC)) > > > > + bridge->domain_nr = pci_bus_find_domain_nr(sys, NULL); > > > > > > The check for CONFIG_PCI_DOMAINS_GENERIC is excessive because there is a > > > stub for pci_bus_find_domain_nr(). > > > > > > I'm not an expert in PCI, but maybe the repeated assignment of > > > bridge->domain_nr can live in the generic code, say, in > > > pci_scan_root_bus_bridge(). E.g. it will set the domain_nr when it is zero. > > > > > > > > > > > Yes, this churn should be avoided. We need a sentinel value to detect > > whether the domain_nr is invalid (0 is a valid domain) so generic code > > (ie pci_scan_root_bus_bridge() and friends) has to call generic > > functions to get it (pci_bus_find_domain_nr()). > > > > Agreed. Thank you all for the inputs. > > According to [1], "PCI Conventional" has at most 256 PCI bus segments > and "PCI Express" has at most 65536 "PCI Segments Groups", so any value > outside [0, 65536] can be used as a sentinel. I'm planning to use -1 > like: > > #define PCI_DOMAIN_NR_NOT_SET (-1) > > (in pci_alloc_host_bridge()) > bridge->domain_nr = PCI_DOMAIN_NR_NOT_SET; > > (in pci_register_host_bridge()) > if (bridge->domain_nr == PCI_DOMAIN_NR_NOT_SET) > bridge->domain_nr = pci_bus_find_domain_nr(...); It should be fine. I'd move the check if (bridge->domain_nr == PCI_DOMAIN_NR_NOT_SET) in pci_bus_find_domain_nr() to make the logic contained in there but that's a nit. Lorenzo > Thoughts? > > Regards, > Boqun > > [1]: https://wiki.osdev.org/PCI_Express > > > We can implement it as a flag or function pointer in the struct > > pci_host_bridge, if the flag or function pointer is not set the > > generic pci_bus_find_domain_nr() should be called. > > > > Lorenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel