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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FAKE_REPLY_C,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 8006FC10F14 for ; Thu, 3 Oct 2019 21:01:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4732D20862 for ; Thu, 3 Oct 2019 21:01:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570136492; bh=B8+adM7hxMw6G43sPG0uzO+Wnf1dj2aZNxz2yxmNHrM=; h=Date:From:To:Cc:Subject:In-Reply-To:List-ID:From; b=uw56MbMFtRuMMCtytqKwwlfdW8Y7ZfTMhP+HCyJIjSx64jpcvDQJrIF6dhYRWHilM AuAp/JtVo8OIYBwOhXL9fNtrT7y89vwUyNKQWKCeeYd89yvVqFzOxjWz5TtVuNVqa5 ozwQb5Ue00jFVkYfxeqoMdJA4i5gdnQBKkozpxgA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729047AbfJCVBb (ORCPT ); Thu, 3 Oct 2019 17:01:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:45772 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728869AbfJCVBb (ORCPT ); Thu, 3 Oct 2019 17:01:31 -0400 Received: from localhost (unknown [69.71.4.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CB3EC20862; Thu, 3 Oct 2019 21:01:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570136490; bh=B8+adM7hxMw6G43sPG0uzO+Wnf1dj2aZNxz2yxmNHrM=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=A7GofkGDKPMFc9KmRt9LHxIN+iTgM+0bbZUL8rII+T7zvKgosbX6oaYrgUXn8XkuL Flg5H02RdJAlwL5DK6LX9sR6Hh8EigB5q0LVefP8rrK1WEvlYjlnuGldK8Ndygp/gI KO1MRfB/crDP6Jbptn0vc1a1MmyEK0CXB6GUikYk= Date: Thu, 3 Oct 2019 16:01:28 -0500 From: Bjorn Helgaas To: Kuppuswamy Sathyanarayanan Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, ashok.raj@intel.com, keith.busch@intel.com Subject: Re: [PATCH v7 1/7] PCI/ATS: Fix pci_prg_resp_pasid_required() dependency issues Message-ID: <20191003210128.GA200289@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191003203726.GA14637@skuppusw-desk.amr.corp.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Oct 03, 2019 at 01:37:26PM -0700, Kuppuswamy Sathyanarayanan wrote: > On Thu, Oct 03, 2019 at 02:04:13PM -0500, Bjorn Helgaas wrote: > > On Thu, Oct 03, 2019 at 10:20:24AM -0700, Kuppuswamy Sathyanarayanan wrote: > > > Hi Bjorn, > > > > > > Thanks for looking into this patch set. > > > > > > On 9/5/19 12:18 PM, Bjorn Helgaas wrote: > > > > On Wed, Aug 28, 2019 at 03:14:01PM -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. > > > > > > > > > > Fixes: e5567f5f6762 ("PCI/ATS: Add pci_prg_resp_pasid_required() > > > > > interface.") > > > > [Don't split tags, including "Fixes:" across lines] > > > > > > > > This definitely doesn't fix e5567f5f6762. That commit added > > > > pci_prg_resp_pasid_required(), but with no dependency on > > > > CONFIG_PCI_PRI or CONFIG_PCI_PASID. > > > > > > > > This patch is only required when a subsequent patch is applied. It > > > > should be squashed into the commit that requires it so it's obvious > > > > why it's needed. > > > > > > > > I've been poking at this series, and I'll post a v8 soon with this and > > > > other fixes. > > > In your v8 submission you did not merge this patch. You did not use > > > pri_cap or pasid_cap cached values. Instead you have re-read the > > > value from register. Is this intentional? > > > > > > Since this function will be called for every VF device we might loose some > > > performance benefit. > > > > This particular patch doesn't do any caching. IIRC it fiddles with > > ifdefs to solve a problem that would be introduced by a future patch. > > I don't remember the exact details, but I think the series I merged > > doesn't have that problem. If it does, let me know the details and we > > can fix it. > This patch by itself does not do any caching. But your caching patch > missed modifying this function to use cached values. Please check the > current implementation of this function. It still reads > PCI_EXT_CAP_ID_PRI register instead of using cached value. Please let > me know your comments. > > int pci_prg_resp_pasid_required(struct pci_dev *pdev) > { > u16 status; > int pri; > > if (pdev->is_virtfn) > pdev = pci_physfn(pdev); > > pri = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI); > if (!pri) > return 0; > > pci_read_config_word(pdev, pri + PCI_PRI_STATUS, &status); > > if (status & PCI_PRI_STATUS_PASID) > return 1; > > return 0; > } > EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required); > > If caching is applied to this function then we need this #ifdef > dependency correction patch. IIRC this #ifdef patch wasn't connected to the actual *need* for the #ifdef, so it was very difficult to review. I thought this function would be infrequently used and it wasn't worth trying to sort out the #ifdef muddle to do the caching. But it does seem sort of pointless to chase the capability list again here, so maybe it *is* worth optimizing. The PRG Response PASID Required bit is read-only, so I wonder if it would be simpler if we just read PCI_PRI_STATUS once and save the bit in the struct pci_dev? We could do that in pci_enable_pri(), or if we might need the value before that's called, we could add a pci_pri_init() and do it there. > > I did include the caching patches for both PRI and PASID capabilities, > > but they're only performance optimizations so I moved them to the end > > so the functional fixes would be smaller and earlier in the series. > > > > > > > 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 e18499243f84..cdd936d10f68 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 > > > > > -- > Sathyanarayanan Kuppuswamy > Linux kernel developer