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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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2dd9c11b9d
This patch leverages 'struct pci_host_bridge' from the PCI subsystem in order to free the pci_controller only after the last reference to its devices is dropped (avoiding an oops in pcibios_release_device() if the last reference is dropped after pcibios_free_controller()). The patch relies on pci_host_bridge.release_fn() (and .release_data), which is called automatically by the PCI subsystem when the root bus is released (i.e., the last reference is dropped). Those fields are set via pci_set_host_bridge_release() (e.g. in the platform-specific implementation of pcibios_root_bridge_prepare()). It introduces the 'pcibios_free_controller_deferred()' .release_fn() and it expects .release_data to hold a pointer to the pci_controller. The function implictly calls 'pcibios_free_controller()', so an user must *NOT* explicitly call it if using the new _deferred() callback. The functionality is enabled for pseries (although it isn't platform specific, and may be used by cxl). Details on not-so-elegant design choices: - Use 'pci_host_bridge.release_data' field as pointer to associated 'struct pci_controller' so *not* to 'pci_bus_to_host(bridge->bus)' in pcibios_free_controller_deferred(). That's because pci_remove_root_bus() sets 'host_bridge->bus = NULL' (so, if the last reference is released after pci_remove_root_bus() runs, which eventually reaches pcibios_free_controller_deferred(), that would hit a null pointer dereference). The cxl/vphb.c code calls pci_remove_root_bus(), and the cxl folks are interested in this fix. Test-case #1 (hold references) # ls -ld /sys/block/sd* | grep -m1 0021:01:00.0 <...> /sys/block/sdaa -> ../devices/pci0021:01/0021:01:00.0/<...> # ls -ld /sys/block/sd* | grep -m1 0021:01:00.1 <...> /sys/block/sdab -> ../devices/pci0021:01/0021:01:00.1/<...> # cat >/dev/sdaa & pid1=$! # cat >/dev/sdab & pid2=$! # drmgr -w 5 -d 1 -c phb -s 'PHB 33' -r Validating PHB DLPAR capability...yes. [ 594.306719] pci_hp_remove_devices: PCI: Removing devices on bus 0021:01 [ 594.306738] pci_hp_remove_devices: Removing 0021:01:00.0... ... [ 598.236381] pci_hp_remove_devices: Removing 0021:01:00.1... ... [ 611.972077] pci_bus 0021:01: busn_res: [bus 01-ff] is released [ 611.972140] rpadlpar_io: slot PHB 33 removed # kill -9 $pid1 # kill -9 $pid2 [ 632.918088] pcibios_free_controller_deferred: domain 33, dynamic 1 Test-case #2 (don't hold references) # drmgr -w 5 -d 1 -c phb -s 'PHB 33' -r Validating PHB DLPAR capability...yes. [ 916.357363] pci_hp_remove_devices: PCI: Removing devices on bus 0021:01 [ 916.357386] pci_hp_remove_devices: Removing 0021:01:00.0... ... [ 920.566527] pci_hp_remove_devices: Removing 0021:01:00.1... ... [ 933.955873] pci_bus 0021:01: busn_res: [bus 01-ff] is released [ 933.955977] pcibios_free_controller_deferred: domain 33, dynamic 1 [ 933.955999] rpadlpar_io: slot PHB 33 removed Suggested-By: Gavin Shan <gwshan@linux.vnet.ibm.com> Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com> Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com> Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Tested-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
118 lines
3.1 KiB
C
118 lines
3.1 KiB
C
/*
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* PCI Dynamic LPAR, PCI Hot Plug and PCI EEH recovery code
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* for RPA-compliant PPC64 platform.
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* Copyright (C) 2003 Linda Xie <lxie@us.ibm.com>
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* Copyright (C) 2005 International Business Machines
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*
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* Updates, 2005, John Rose <johnrose@austin.ibm.com>
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* Updates, 2005, Linas Vepstas <linas@austin.ibm.com>
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or (at
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* your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/pci.h>
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#include <linux/export.h>
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#include <asm/pci-bridge.h>
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#include <asm/ppc-pci.h>
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#include <asm/firmware.h>
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#include <asm/eeh.h>
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#include "pseries.h"
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struct pci_controller *init_phb_dynamic(struct device_node *dn)
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{
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struct pci_controller *phb;
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pr_debug("PCI: Initializing new hotplug PHB %s\n", dn->full_name);
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phb = pcibios_alloc_controller(dn);
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if (!phb)
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return NULL;
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rtas_setup_phb(phb);
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pci_process_bridge_OF_ranges(phb, dn, 0);
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phb->controller_ops = pseries_pci_controller_ops;
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pci_devs_phb_init_dynamic(phb);
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/* Create EEH devices for the PHB */
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eeh_dev_phb_init_dynamic(phb);
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if (dn->child)
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eeh_add_device_tree_early(PCI_DN(dn));
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pcibios_scan_phb(phb);
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pcibios_finish_adding_to_bus(phb->bus);
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return phb;
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}
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EXPORT_SYMBOL_GPL(init_phb_dynamic);
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/* RPA-specific bits for removing PHBs */
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int remove_phb_dynamic(struct pci_controller *phb)
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{
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struct pci_bus *b = phb->bus;
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struct resource *res;
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int rc, i;
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pr_debug("PCI: Removing PHB %04x:%02x...\n",
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pci_domain_nr(b), b->number);
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/* We cannot to remove a root bus that has children */
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if (!(list_empty(&b->children) && list_empty(&b->devices)))
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return -EBUSY;
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/* We -know- there aren't any child devices anymore at this stage
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* and thus, we can safely unmap the IO space as it's not in use
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*/
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res = &phb->io_resource;
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if (res->flags & IORESOURCE_IO) {
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rc = pcibios_unmap_io_space(b);
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if (rc) {
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printk(KERN_ERR "%s: failed to unmap IO on bus %s\n",
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__func__, b->name);
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return 1;
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}
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}
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/* Remove the PCI bus and unregister the bridge device from sysfs */
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phb->bus = NULL;
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pci_remove_bus(b);
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device_unregister(b->bridge);
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/* Now release the IO resource */
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if (res->flags & IORESOURCE_IO)
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release_resource(res);
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/* Release memory resources */
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for (i = 0; i < 3; ++i) {
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res = &phb->mem_resources[i];
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if (!(res->flags & IORESOURCE_MEM))
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continue;
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release_resource(res);
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}
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/*
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* The pci_controller data structure is freed by
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* the pcibios_free_controller_deferred() callback;
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* see pseries_root_bridge_prepare().
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*/
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return 0;
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}
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EXPORT_SYMBOL_GPL(remove_phb_dynamic);
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