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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT 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 E5366C43381 for ; Tue, 26 Mar 2019 20:20:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B668D2075C for ; Tue, 26 Mar 2019 20:20:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553631659; bh=WlX3mKU7ybiZhB/KyE7ButxaXqtd5qA2M5Dl9dJjWTQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Dwcl8RdIqgCpadhfeT60+KL82I97gRiyZEHaJphdEiHXOViVvMgmyjJ16JTON9TJh y/OOiXI3iYD+CFuD2u1vNSeu1fqv+uHUFinvW/BwQsexfCRNbKQuK88xW/HT2OyOt9 GDCUQhw859p+WKgCfvEoc32LBj1ZC+QIlg2dmjzk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731832AbfCZUU7 (ORCPT ); Tue, 26 Mar 2019 16:20:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:46028 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731736AbfCZUU7 (ORCPT ); Tue, 26 Mar 2019 16:20:59 -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 5473820657; Tue, 26 Mar 2019 20:20:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553631657; bh=WlX3mKU7ybiZhB/KyE7ButxaXqtd5qA2M5Dl9dJjWTQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lCpYKWtMfFgGUD3pGqWHfPg5Urxvob4sjxEJnjqf/ReMO4qSgGqsTwea34UhdNTdM Ybd46hyXcUeIUeC/pupENwrrx5bFZQOdDI6cmbUXvw6W44eeGc4n2KHUH6pbi+ztCh Crmf+Kk96tntguibsrvalzBYHjq6SwDnIWnBax4k= Date: Tue, 26 Mar 2019 15:20:55 -0500 From: Bjorn Helgaas To: Sergey Miroshnichenko Cc: linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux@yadro.com, Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC v4 08/21] nvme-pci: Handle movable BARs Message-ID: <20190326202055.GP24180@google.com> References: <20190311133122.11417-1-s.miroshnichenko@yadro.com> <20190311133122.11417-9-s.miroshnichenko@yadro.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190311133122.11417-9-s.miroshnichenko@yadro.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 [+cc Keith, Jens, Christoph, Sagi, linux-nvme, LKML] On Mon, Mar 11, 2019 at 04:31:09PM +0300, Sergey Miroshnichenko wrote: > Hotplugged devices can affect the existing ones by moving their BARs. > PCI subsystem will inform the NVME driver about this by invoking > reset_prepare()+reset_done(), then iounmap()+ioremap() must be called. Do you mean the PCI core will invoke ->rescan_prepare() and ->rescan_done() (as opposed to *reset*)? > Signed-off-by: Sergey Miroshnichenko > --- > drivers/nvme/host/pci.c | 29 +++++++++++++++++++++++++++-- > 1 file changed, 27 insertions(+), 2 deletions(-) > > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c > index 92bad1c810ac..ccea3033a67a 100644 > --- a/drivers/nvme/host/pci.c > +++ b/drivers/nvme/host/pci.c > @@ -106,6 +106,7 @@ struct nvme_dev { > unsigned int num_vecs; > int q_depth; > u32 db_stride; > + resource_size_t current_phys_bar; > void __iomem *bar; > unsigned long bar_mapped_size; > struct work_struct remove_work; > @@ -1672,13 +1673,16 @@ static int nvme_remap_bar(struct nvme_dev *dev, unsigned long size) > { > struct pci_dev *pdev = to_pci_dev(dev->dev); > > - if (size <= dev->bar_mapped_size) > + if (dev->bar && > + dev->current_phys_bar == pci_resource_start(pdev, 0) && > + size <= dev->bar_mapped_size) > return 0; > if (size > pci_resource_len(pdev, 0)) > return -ENOMEM; > if (dev->bar) > iounmap(dev->bar); > - dev->bar = ioremap(pci_resource_start(pdev, 0), size); > + dev->current_phys_bar = pci_resource_start(pdev, 0); > + dev->bar = ioremap(dev->current_phys_bar, size); dev->current_phys_bar is different from pci_resource_start() in the case where the PCI core has moved the nvme BAR, but nvme has not yet remapped it. I'm not sure it's worth keeping track of current_phys_bar, as opposed to always unmapping and remapping. Is this a performance path? I think there are advantages to always exercising the same code path, regardless of whether the BAR happened to be moved, e.g., if there's a bug in the "BAR moved" path, it may be a heisenbug because whether we exercise that path depends on the current configuration. If you do need to cache current_phys_bar, maybe this, so it's a little easier to see that you're not changing the ioremap() itself: dev->bar = ioremap(pci_resource_start(pdev, 0), size); dev->current_phys_bar = pci_resource_start(pdev, 0); > if (!dev->bar) { > dev->bar_mapped_size = 0; > return -ENOMEM; > @@ -2504,6 +2508,8 @@ static void nvme_reset_work(struct work_struct *work) > if (WARN_ON(dev->ctrl.state != NVME_CTRL_RESETTING)) > goto out; > > + nvme_remap_bar(dev, db_bar_size(dev, 0)); How is this change connected to rescan? This looks reset-related. > /* > * If we're called to reset a live controller first shut it down before > * moving on. > @@ -2910,6 +2916,23 @@ static void nvme_error_resume(struct pci_dev *pdev) > flush_work(&dev->ctrl.reset_work); > } > > +void nvme_rescan_prepare(struct pci_dev *pdev) > +{ > + struct nvme_dev *dev = pci_get_drvdata(pdev); > + > + nvme_dev_disable(dev, false); > + nvme_dev_unmap(dev); > + dev->bar = NULL; > +} > + > +void nvme_rescan_done(struct pci_dev *pdev) > +{ > + struct nvme_dev *dev = pci_get_drvdata(pdev); > + > + nvme_dev_map(dev); > + nvme_reset_ctrl_sync(&dev->ctrl); > +} > + > static const struct pci_error_handlers nvme_err_handler = { > .error_detected = nvme_error_detected, > .slot_reset = nvme_slot_reset, > @@ -2974,6 +2997,8 @@ static struct pci_driver nvme_driver = { > }, > .sriov_configure = pci_sriov_configure_simple, > .err_handler = &nvme_err_handler, > + .rescan_prepare = nvme_rescan_prepare, > + .rescan_done = nvme_rescan_done, > }; > > static int __init nvme_init(void) > -- > 2.20.1 >