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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 B3188C0650E for ; Wed, 3 Jul 2019 18:25:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 90DD321881 for ; Wed, 3 Jul 2019 18:25:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727186AbfGCSZy (ORCPT ); Wed, 3 Jul 2019 14:25:54 -0400 Received: from mga01.intel.com ([192.55.52.88]:6475 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725933AbfGCSZw (ORCPT ); Wed, 3 Jul 2019 14:25:52 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 03 Jul 2019 11:25:45 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,446,1557212400"; d="scan'208";a="315655248" Received: from linux.intel.com ([10.54.29.200]) by orsmga004.jf.intel.com with ESMTP; 03 Jul 2019 11:25:45 -0700 Received: from [10.54.74.33] (skuppusw-desk.jf.intel.com [10.54.74.33]) by linux.intel.com (Postfix) with ESMTP id A021258060A; Wed, 3 Jul 2019 11:25:45 -0700 (PDT) Reply-To: sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH v3 1/7] PCI/ATS: Fix pci_prg_resp_pasid_required() dependency issues To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, ashok.raj@intel.com, keith.busch@intel.com References: <20190703175654.GN128603@google.com> From: sathyanarayanan kuppuswamy Organization: Intel Message-ID: Date: Wed, 3 Jul 2019 11:23:37 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190703175654.GN128603@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 7/3/19 10:56 AM, Bjorn Helgaas wrote: > On Thu, Jun 20, 2019 at 01:38:42PM -0700, sathyanarayanan.kuppuswamy@linux.intel.com wrote: >> From: Kuppuswamy Sathyanarayanan >> >> Since pci_prg_resp_pasid_required() function has dependency on both >> PASID and PRI, define it only if both CONFIG_PCI_PRI and >> CONFIG_PCI_PASID config options are enabled. > This is likely just confusion on my part, but I don't understand what > you're doing here. > > pci_prg_resp_pasid_required() does not actually *depend* on the > CONFIG_PCI_PRI config symbol. pci_prg_resp_pasid_required() function internally reads the PRI status register to get the status of PASID required bit. FILE:drivers/pci/ats.c 419         pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status); 420 421         if (status & PCI_PRI_STATUS_PASID) Since pci_prg_resp_pasid_required()  function is only used if CONFIG_PCI_PASID is enabled, and since it also has internal PCI_PRI dependency, I have protected it with both CONFIG_PCI_PASID and CONFIG_PCI_PRI ifdefs. > > It is currently compiled only if CONFIG_PCI_ATS=y (which controls > compilation of the entire ats.c) and CONFIG_PCI_PASID=y (since it's > within #ifdef CONFIG_PCI_PASID). > > pci_prg_resp_pasid_required() is called by attach_device() > (amd_iommu.c), which is only compiled if CONFIG_AMD_IOMMU=y, and that > selects PCI_PRI. pci_prg_resp_pasid_required() is also called by intel_iommu.c, and enabling CONFIG_INTEL_IOMMU does not enable PCI_PRI/PCI_PASID by default. > > It is also called by iommu_enable_dev_iotlb() (intel-iommu.c). That > file is compiled if CONFIG_INTEL_IOMMU=y and the call itself is inside > #ifdef CONFIG_INTEL_IOMMU_SVM. But I don't see the PCI_PRI connection > here. > > If this is just to limit the visibility, say that. But I don't think > that's really a good reason. The chain of config symbols seems a > little too complicated. > >> Fixes: e5567f5f6762 ("PCI/ATS: Add pci_prg_resp_pasid_required() >> interface.") >> Signed-off-by: Kuppuswamy Sathyanarayanan >> --- >> drivers/pci/ats.c | 10 ++++++---- >> include/linux/pci-ats.h | 12 +++++++++--- >> 2 files changed, 15 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c >> index 97c08146534a..f9eeb7db0db3 100644 >> --- a/drivers/pci/ats.c >> +++ b/drivers/pci/ats.c >> @@ -395,6 +395,8 @@ int pci_pasid_features(struct pci_dev *pdev) >> } >> EXPORT_SYMBOL_GPL(pci_pasid_features); >> >> +#ifdef CONFIG_PCI_PRI >> + >> /** >> * pci_prg_resp_pasid_required - Return PRG Response PASID Required bit >> * status. >> @@ -402,10 +404,8 @@ EXPORT_SYMBOL_GPL(pci_pasid_features); >> * >> * Returns 1 if PASID is required in PRG Response Message, 0 otherwise. >> * >> - * Even though the PRG response PASID status is read from PRI Status >> - * Register, since this API will mainly be used by PASID users, this >> - * function is defined within #ifdef CONFIG_PCI_PASID instead of >> - * CONFIG_PCI_PRI. >> + * Since this API has dependency on both PRI and PASID, protect it >> + * with both CONFIG_PCI_PRI and CONFIG_PCI_PASID. >> */ >> int pci_prg_resp_pasid_required(struct pci_dev *pdev) >> { >> @@ -425,6 +425,8 @@ int pci_prg_resp_pasid_required(struct pci_dev *pdev) >> } >> EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required); >> >> +#endif >> + >> #define PASID_NUMBER_SHIFT 8 >> #define PASID_NUMBER_MASK (0x1f << PASID_NUMBER_SHIFT) >> /** >> diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h >> index 1ebb88e7c184..1a0bdaee2f32 100644 >> --- a/include/linux/pci-ats.h >> +++ b/include/linux/pci-ats.h >> @@ -40,7 +40,6 @@ void pci_disable_pasid(struct pci_dev *pdev); >> void pci_restore_pasid_state(struct pci_dev *pdev); >> int pci_pasid_features(struct pci_dev *pdev); >> int pci_max_pasids(struct pci_dev *pdev); >> -int pci_prg_resp_pasid_required(struct pci_dev *pdev); >> >> #else /* CONFIG_PCI_PASID */ >> >> @@ -67,11 +66,18 @@ static inline int pci_max_pasids(struct pci_dev *pdev) >> return -EINVAL; >> } >> >> +#endif /* CONFIG_PCI_PASID */ >> + >> +#if defined(CONFIG_PCI_PRI) && defined(CONFIG_PCI_PASID) >> + >> +int pci_prg_resp_pasid_required(struct pci_dev *pdev); >> + >> +#else /* CONFIG_PCI_PASID && CONFIG_PCI_PRI */ >> + >> static inline int pci_prg_resp_pasid_required(struct pci_dev *pdev) >> { >> return 0; >> } >> -#endif /* CONFIG_PCI_PASID */ >> - >> +#endif >> >> #endif /* LINUX_PCI_ATS_H*/ >> -- >> 2.21.0 >> -- Sathyanarayanan Kuppuswamy Linux kernel developer