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, 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 8319FC43381 for ; Tue, 26 Mar 2019 20:55:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4039A20896 for ; Tue, 26 Mar 2019 20:55:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553633737; bh=tA+yhLyPz3pS7/zaWIUUT5xew+vLqD4acHfJaRD1P4E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=S5lRvPMEiNhKfwCnbiAGURP0TFa4snB3RI0DibbSyxFOZqqreM9Ojc03NgZDI/R4f KXVyFv1O1bvc7djvuoQd1SxpaN+eEr6VwzMjDnD0+moSPExN6GNyZV1bfUMt3NWULy zLKNo/gqjXg2Oh15P6aYtS4Zsf7kgX5MCv33y3is= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731736AbfCZUzg (ORCPT ); Tue, 26 Mar 2019 16:55:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:34348 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726811AbfCZUzg (ORCPT ); Tue, 26 Mar 2019 16:55:36 -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 A7DDD20700; Tue, 26 Mar 2019 20:55:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553633735; bh=tA+yhLyPz3pS7/zaWIUUT5xew+vLqD4acHfJaRD1P4E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=up4eFBISWZopYl29DTampIL5GX6OR90ICwYe3llJ9TGTv4JnIB6KuruJB46dIpVDa PNm+dEIOSCozbESZfUrzkdjLRAJ63SIYF8E+8qdYccBk7btsA+IlgCSq8oQ32XdsCx QwJzAPg/XsuHw/BTaOIK4Ln6z/eWCbg/wAFgID/A= Date: Tue, 26 Mar 2019 15:55:33 -0500 From: Bjorn Helgaas To: Sergey Miroshnichenko Cc: linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux@yadro.com Subject: Re: [PATCH RFC v4 12/21] PCI: Don't allow hotplugged devices to steal resources Message-ID: <20190326205533.GT24180@google.com> References: <20190311133122.11417-1-s.miroshnichenko@yadro.com> <20190311133122.11417-13-s.miroshnichenko@yadro.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190311133122.11417-13-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 On Mon, Mar 11, 2019 at 04:31:13PM +0300, Sergey Miroshnichenko wrote: > When movable BARs are enabled, the PCI subsystem at first releases > all the bridge windows and then performs an attempt to assign new > requested resources and re-assign the existing ones. s/performs an attempt/attempts/ I guess "new requested resources" means "resources to newly hotplugged devices"? > If a hotplugged device gets its resources first, there could be no > space left to re-assign resources of already working devices, which > is unacceptable. If this happens, this patch marks one of the new > devices with the new introduced flag PCI_DEV_IGNORE and retries the > resource assignment. > > This patch adds a new res_mask bitmask to the struct pci_dev for > storing the indices of assigned resources. > > Signed-off-by: Sergey Miroshnichenko > --- > drivers/pci/bus.c | 5 ++ > drivers/pci/pci.h | 11 +++++ > drivers/pci/probe.c | 100 +++++++++++++++++++++++++++++++++++++++- > drivers/pci/setup-bus.c | 15 ++++++ > include/linux/pci.h | 1 + > 5 files changed, 130 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c > index 5cb40b2518f9..a9784144d6f2 100644 > --- a/drivers/pci/bus.c > +++ b/drivers/pci/bus.c > @@ -311,6 +311,11 @@ void pci_bus_add_device(struct pci_dev *dev) > { > int retval; > > + if (pci_dev_is_ignored(dev)) { > + pci_warn(dev, "%s: don't enable the ignored device\n", __func__); > + return; I'm not sure about this. Even if we're unable to assign space for all the device's BARs, it still should respond to config accesses, and I think it should show up in sysfs and lspci. > + } > + > /* > * Can not put in pci_device_add yet because resources > * are not assigned yet for some devices. > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h > index e06e8692a7b1..56b905068ac5 100644 > --- a/drivers/pci/pci.h > +++ b/drivers/pci/pci.h > @@ -366,6 +366,7 @@ static inline bool pci_dev_is_disconnected(const struct pci_dev *dev) > > /* pci_dev priv_flags */ > #define PCI_DEV_ADDED 0 > +#define PCI_DEV_IGNORE 1 > > static inline void pci_dev_assign_added(struct pci_dev *dev, bool added) > { > @@ -377,6 +378,16 @@ static inline bool pci_dev_is_added(const struct pci_dev *dev) > return test_bit(PCI_DEV_ADDED, &dev->priv_flags); > } > > +static inline void pci_dev_ignore(struct pci_dev *dev, bool ignore) > +{ > + assign_bit(PCI_DEV_IGNORE, &dev->priv_flags, ignore); > +} > + > +static inline bool pci_dev_is_ignored(const struct pci_dev *dev) > +{ > + return test_bit(PCI_DEV_IGNORE, &dev->priv_flags); > +} > + > #ifdef CONFIG_PCIEAER > #include > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index 692752c71f71..62f4058a001f 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -3248,6 +3248,23 @@ unsigned int pci_rescan_bus_bridge_resize(struct pci_dev *bridge) > return max; > } > > +static unsigned int pci_dev_res_mask(struct pci_dev *dev) > +{ > + unsigned int res_mask = 0; > + int i; > + > + for (i = 0; i < PCI_BRIDGE_RESOURCES; i++) { > + struct resource *r = &dev->resource[i]; > + > + if (!r->flags || (r->flags & IORESOURCE_UNSET) || !r->parent) > + continue; > + > + res_mask |= (1 << i); > + } > + > + return res_mask; > +} > + > static void pci_bus_rescan_prepare(struct pci_bus *bus) > { > struct pci_dev *dev; > @@ -3257,6 +3274,8 @@ static void pci_bus_rescan_prepare(struct pci_bus *bus) > list_for_each_entry(dev, &bus->devices, bus_list) { > struct pci_bus *child = dev->subordinate; > > + dev->res_mask = pci_dev_res_mask(dev); > + > if (child) { > pci_bus_rescan_prepare(child); > } else if (dev->driver && > @@ -3318,6 +3337,84 @@ static void pci_setup_bridges(struct pci_bus *bus) > pci_setup_bridge(bus); > } > > +static struct pci_dev *pci_find_next_new_device(struct pci_bus *bus) > +{ > + struct pci_dev *dev; > + > + if (!bus) > + return NULL; > + > + list_for_each_entry(dev, &bus->devices, bus_list) { > + struct pci_bus *child_bus = dev->subordinate; > + > + if (!pci_dev_is_added(dev) && !pci_dev_is_ignored(dev)) > + return dev; > + > + if (child_bus) { > + struct pci_dev *next_new_dev; > + > + next_new_dev = pci_find_next_new_device(child_bus); > + if (next_new_dev) > + return next_new_dev; > + } > + } > + > + return NULL; > +} > + > +static bool pci_bus_validate_resources(struct pci_bus *bus) The name of this function should tell us what the return value means. Just from the name "pci_bus_validate_resources", I can't tell whether we call it for side-effects, or whether true or false indicates success. > +{ > + struct pci_dev *dev; > + bool ret = true; > + > + if (!bus) > + return false; > + > + list_for_each_entry(dev, &bus->devices, bus_list) { > + struct pci_bus *child = dev->subordinate; > + unsigned int res_mask = pci_dev_res_mask(dev); > + > + if (pci_dev_is_ignored(dev)) > + continue; > + > + if (dev->res_mask & ~res_mask) { > + pci_err(dev, "%s: Non-re-enabled resources found: 0x%x -> 0x%x\n", > + __func__, dev->res_mask, res_mask); I don't think __func__ really tells users anything useful, so I would just omit them. Searching for the text of the message is almost as good. > + ret = false; > + } > + > + if (child && !pci_bus_validate_resources(child)) > + ret = false; > + } > + > + return ret; > +} > + > +static void pci_reassign_root_bus_resources(struct pci_bus *root) > +{ > + do { > + struct pci_dev *next_new_dev; > + > + pci_bus_release_root_bridge_resources(root); > + pci_assign_unassigned_root_bus_resources(root); > + > + if (pci_bus_validate_resources(root)) > + break; > + > + next_new_dev = pci_find_next_new_device(root); > + if (!next_new_dev) { > + dev_err(&root->dev, "%s: failed to re-assign resources even after ignoring all the hotplugged devices\n", > + __func__); > + break; > + } > + > + dev_warn(&root->dev, "%s: failed to re-assign resources, disable the next hotplugged device %s and retry\n", > + __func__, dev_name(&next_new_dev->dev)); > + > + pci_dev_ignore(next_new_dev, true); > + } while (true); > +} > + > /** > * pci_rescan_bus - Scan a PCI bus for devices > * @bus: PCI bus to scan > @@ -3341,8 +3438,7 @@ unsigned int pci_rescan_bus(struct pci_bus *bus) > > max = pci_scan_child_bus(root); > > - pci_bus_release_root_bridge_resources(root); > - pci_assign_unassigned_root_bus_resources(root); > + pci_reassign_root_bus_resources(root); > > pci_setup_bridges(root); > pci_bus_rescan_done(root); > diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c > index 36a1907d9509..551108f48df7 100644 > --- a/drivers/pci/setup-bus.c > +++ b/drivers/pci/setup-bus.c > @@ -131,6 +131,9 @@ static void pdev_sort_resources(struct pci_dev *dev, struct list_head *head) > { > int i; > > + if (pci_dev_is_ignored(dev)) > + return; > + > for (i = 0; i < PCI_NUM_RESOURCES; i++) { > struct resource *r; > struct pci_dev_resource *dev_res, *tmp; > @@ -181,6 +184,9 @@ static void __dev_sort_resources(struct pci_dev *dev, > { > u16 class = dev->class >> 8; > > + if (pci_dev_is_ignored(dev)) > + return; > + > /* Don't touch classless devices or host bridges or ioapics. */ > if (class == PCI_CLASS_NOT_DEFINED || class == PCI_CLASS_BRIDGE_HOST) > return; > @@ -284,6 +290,9 @@ static void assign_requested_resources_sorted(struct list_head *head, > int idx; > > list_for_each_entry(dev_res, head, list) { > + if (pci_dev_is_ignored(dev_res->dev)) > + continue; > + > res = dev_res->res; > idx = res - &dev_res->dev->resource[0]; > if (resource_size(res) && > @@ -991,6 +1000,9 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, > list_for_each_entry(dev, &bus->devices, bus_list) { > int i; > > + if (pci_dev_is_ignored(dev)) > + continue; > + > for (i = 0; i < PCI_NUM_RESOURCES; i++) { > struct resource *r = &dev->resource[i]; > resource_size_t r_size; > @@ -1353,6 +1365,9 @@ void __pci_bus_assign_resources(const struct pci_bus *bus, > pbus_assign_resources_sorted(bus, realloc_head, fail_head); > > list_for_each_entry(dev, &bus->devices, bus_list) { > + if (pci_dev_is_ignored(dev)) > + continue; > + > pdev_assign_fixed_resources(dev); > > b = dev->subordinate; > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 3d52f5538282..26aa59cb6220 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -369,6 +369,7 @@ struct pci_dev { > */ > unsigned int irq; > struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */ > + unsigned int res_mask; /* Bitmask of assigned resources */ > > bool match_driver; /* Skip attaching driver */ > > -- > 2.20.1 >