![Bjorn Helgaas](/assets/img/avatar_default.png)
When a PCI bus has two resources with the same start/end, e.g., pci_bus 0000:04: resource 2 [mem 0xd0000000-0xd7ffffff pref] pci_bus 0000:04: resource 7 [mem 0xd0000000-0xd7ffffff] the previous pci_bus_find_resource_prev() implementation would alternate between them forever: pci_bus_find_resource_prev(... [mem 0xd0000000-0xd7ffffff pref]) returns [mem 0xd0000000-0xd7ffffff] pci_bus_find_resource_prev(... [mem 0xd0000000-0xd7ffffff]) returns [mem 0xd0000000-0xd7ffffff pref] pci_bus_find_resource_prev(... [mem 0xd0000000-0xd7ffffff pref]) returns [mem 0xd0000000-0xd7ffffff] ... This happened because there was no ordering between two resources with the same start and end. A resource that had the same start and end as the cursor, but was not itself the cursor, was considered to be before the cursor. This patch fixes the hang by making a fixed ordering between any two resources. In addition, it tries to allocate from positively decoded regions before using any subtractively decoded resources. This means we will use a positive decode region before a subtractive decode one, even if it means using a smaller address. Reference: https://bugzilla.kernel.org/show_bug.cgi?id=22062 Reported-by: Borislav Petkov <bp@amd64.org> Tested-by: Borislav Petkov <bp@amd64.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
379 lines
9.5 KiB
C
379 lines
9.5 KiB
C
/*
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* drivers/pci/bus.c
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*
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* From setup-res.c, by:
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* Dave Rusling (david.rusling@reo.mts.dec.com)
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* David Mosberger (davidm@cs.arizona.edu)
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* David Miller (davem@redhat.com)
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* Ivan Kokshaysky (ink@jurassic.park.msu.ru)
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/pci.h>
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#include <linux/errno.h>
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#include <linux/ioport.h>
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#include <linux/proc_fs.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include "pci.h"
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void pci_bus_add_resource(struct pci_bus *bus, struct resource *res,
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unsigned int flags)
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{
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struct pci_bus_resource *bus_res;
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bus_res = kzalloc(sizeof(struct pci_bus_resource), GFP_KERNEL);
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if (!bus_res) {
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dev_err(&bus->dev, "can't add %pR resource\n", res);
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return;
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}
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bus_res->res = res;
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bus_res->flags = flags;
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list_add_tail(&bus_res->list, &bus->resources);
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}
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struct resource *pci_bus_resource_n(const struct pci_bus *bus, int n)
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{
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struct pci_bus_resource *bus_res;
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if (n < PCI_BRIDGE_RESOURCE_NUM)
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return bus->resource[n];
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n -= PCI_BRIDGE_RESOURCE_NUM;
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list_for_each_entry(bus_res, &bus->resources, list) {
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if (n-- == 0)
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return bus_res->res;
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}
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return NULL;
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}
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EXPORT_SYMBOL_GPL(pci_bus_resource_n);
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void pci_bus_remove_resources(struct pci_bus *bus)
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{
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struct pci_bus_resource *bus_res, *tmp;
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int i;
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for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++)
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bus->resource[i] = NULL;
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list_for_each_entry_safe(bus_res, tmp, &bus->resources, list) {
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list_del(&bus_res->list);
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kfree(bus_res);
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}
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}
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static bool pci_bus_resource_better(struct resource *res1, bool pos1,
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struct resource *res2, bool pos2)
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{
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/* If exactly one is positive decode, always prefer that one */
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if (pos1 != pos2)
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return pos1 ? true : false;
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/* Prefer the one that contains the highest address */
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if (res1->end != res2->end)
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return (res1->end > res2->end) ? true : false;
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/* Otherwise, prefer the one with highest "center of gravity" */
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if (res1->start != res2->start)
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return (res1->start > res2->start) ? true : false;
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/* Otherwise, choose one arbitrarily (but consistently) */
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return (res1 > res2) ? true : false;
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}
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static bool pci_bus_resource_positive(struct pci_bus *bus, struct resource *res)
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{
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struct pci_bus_resource *bus_res;
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/*
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* This relies on the fact that pci_bus.resource[] refers to P2P or
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* CardBus bridge base/limit registers, which are always positively
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* decoded. The pci_bus.resources list contains host bridge or
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* subtractively decoded resources.
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*/
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list_for_each_entry(bus_res, &bus->resources, list) {
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if (bus_res->res == res)
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return (bus_res->flags & PCI_SUBTRACTIVE_DECODE) ?
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false : true;
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}
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return true;
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}
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/*
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* Find the next-best bus resource after the cursor "res". If the cursor is
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* NULL, return the best resource. "Best" means that we prefer positive
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* decode regions over subtractive decode, then those at higher addresses.
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*/
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static struct resource *pci_bus_find_resource_prev(struct pci_bus *bus,
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unsigned int type,
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struct resource *res)
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{
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bool res_pos, r_pos, prev_pos = false;
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struct resource *r, *prev = NULL;
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int i;
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res_pos = pci_bus_resource_positive(bus, res);
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pci_bus_for_each_resource(bus, r, i) {
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if (!r)
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continue;
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if ((r->flags & IORESOURCE_TYPE_BITS) != type)
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continue;
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r_pos = pci_bus_resource_positive(bus, r);
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if (!res || pci_bus_resource_better(res, res_pos, r, r_pos)) {
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if (!prev || pci_bus_resource_better(r, r_pos,
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prev, prev_pos)) {
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prev = r;
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prev_pos = r_pos;
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}
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}
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}
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return prev;
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}
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/**
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* pci_bus_alloc_resource - allocate a resource from a parent bus
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* @bus: PCI bus
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* @res: resource to allocate
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* @size: size of resource to allocate
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* @align: alignment of resource to allocate
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* @min: minimum /proc/iomem address to allocate
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* @type_mask: IORESOURCE_* type flags
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* @alignf: resource alignment function
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* @alignf_data: data argument for resource alignment function
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*
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* Given the PCI bus a device resides on, the size, minimum address,
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* alignment and type, try to find an acceptable resource allocation
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* for a specific device resource.
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*/
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int
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pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
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resource_size_t size, resource_size_t align,
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resource_size_t min, unsigned int type_mask,
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resource_size_t (*alignf)(void *,
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const struct resource *,
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resource_size_t,
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resource_size_t),
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void *alignf_data)
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{
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int ret = -ENOMEM;
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struct resource *r;
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resource_size_t max = -1;
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unsigned int type = res->flags & IORESOURCE_TYPE_BITS;
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type_mask |= IORESOURCE_IO | IORESOURCE_MEM;
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/* don't allocate too high if the pref mem doesn't support 64bit*/
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if (!(res->flags & IORESOURCE_MEM_64))
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max = PCIBIOS_MAX_MEM_32;
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/* Look for space at highest addresses first */
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r = pci_bus_find_resource_prev(bus, type, NULL);
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for ( ; r; r = pci_bus_find_resource_prev(bus, type, r)) {
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/* type_mask must match */
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if ((res->flags ^ r->flags) & type_mask)
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continue;
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/* We cannot allocate a non-prefetching resource
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from a pre-fetching area */
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if ((r->flags & IORESOURCE_PREFETCH) &&
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!(res->flags & IORESOURCE_PREFETCH))
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continue;
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/* Ok, try it out.. */
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ret = allocate_resource(r, res, size,
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r->start ? : min,
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max, align,
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alignf, alignf_data);
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if (ret == 0)
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break;
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}
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return ret;
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}
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/**
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* pci_bus_add_device - add a single device
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* @dev: device to add
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*
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* This adds a single pci device to the global
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* device list and adds sysfs and procfs entries
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*/
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int pci_bus_add_device(struct pci_dev *dev)
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{
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int retval;
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retval = device_add(&dev->dev);
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if (retval)
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return retval;
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dev->is_added = 1;
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pci_proc_attach_device(dev);
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pci_create_sysfs_dev_files(dev);
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return 0;
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}
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/**
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* pci_bus_add_child - add a child bus
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* @bus: bus to add
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*
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* This adds sysfs entries for a single bus
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*/
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int pci_bus_add_child(struct pci_bus *bus)
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{
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int retval;
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if (bus->bridge)
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bus->dev.parent = bus->bridge;
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retval = device_register(&bus->dev);
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if (retval)
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return retval;
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bus->is_added = 1;
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retval = device_create_file(&bus->dev, &dev_attr_cpuaffinity);
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if (retval)
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return retval;
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retval = device_create_file(&bus->dev, &dev_attr_cpulistaffinity);
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/* Create legacy_io and legacy_mem files for this bus */
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pci_create_legacy_files(bus);
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return retval;
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}
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/**
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* pci_bus_add_devices - insert newly discovered PCI devices
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* @bus: bus to check for new devices
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*
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* Add newly discovered PCI devices (which are on the bus->devices
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* list) to the global PCI device list, add the sysfs and procfs
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* entries. Where a bridge is found, add the discovered bus to
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* the parents list of child buses, and recurse (breadth-first
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* to be compatible with 2.4)
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*
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* Call hotplug for each new devices.
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*/
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void pci_bus_add_devices(const struct pci_bus *bus)
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{
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struct pci_dev *dev;
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struct pci_bus *child;
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int retval;
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list_for_each_entry(dev, &bus->devices, bus_list) {
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/* Skip already-added devices */
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if (dev->is_added)
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continue;
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retval = pci_bus_add_device(dev);
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if (retval)
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dev_err(&dev->dev, "Error adding device, continuing\n");
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}
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list_for_each_entry(dev, &bus->devices, bus_list) {
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BUG_ON(!dev->is_added);
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child = dev->subordinate;
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/*
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* If there is an unattached subordinate bus, attach
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* it and then scan for unattached PCI devices.
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*/
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if (!child)
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continue;
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if (list_empty(&child->node)) {
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down_write(&pci_bus_sem);
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list_add_tail(&child->node, &dev->bus->children);
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up_write(&pci_bus_sem);
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}
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pci_bus_add_devices(child);
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/*
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* register the bus with sysfs as the parent is now
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* properly registered.
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*/
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if (child->is_added)
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continue;
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retval = pci_bus_add_child(child);
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if (retval)
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dev_err(&dev->dev, "Error adding bus, continuing\n");
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}
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}
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void pci_enable_bridges(struct pci_bus *bus)
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{
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struct pci_dev *dev;
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int retval;
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list_for_each_entry(dev, &bus->devices, bus_list) {
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if (dev->subordinate) {
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if (!pci_is_enabled(dev)) {
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retval = pci_enable_device(dev);
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if (retval)
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dev_err(&dev->dev, "Error enabling bridge (%d), continuing\n", retval);
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pci_set_master(dev);
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}
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pci_enable_bridges(dev->subordinate);
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}
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}
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}
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/** pci_walk_bus - walk devices on/under bus, calling callback.
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* @top bus whose devices should be walked
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* @cb callback to be called for each device found
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* @userdata arbitrary pointer to be passed to callback.
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*
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* Walk the given bus, including any bridged devices
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* on buses under this bus. Call the provided callback
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* on each device found.
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*
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* We check the return of @cb each time. If it returns anything
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* other than 0, we break out.
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*
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*/
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void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
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void *userdata)
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{
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struct pci_dev *dev;
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struct pci_bus *bus;
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struct list_head *next;
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int retval;
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bus = top;
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down_read(&pci_bus_sem);
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next = top->devices.next;
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for (;;) {
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if (next == &bus->devices) {
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/* end of this bus, go up or finish */
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if (bus == top)
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break;
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next = bus->self->bus_list.next;
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bus = bus->self->bus;
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continue;
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}
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dev = list_entry(next, struct pci_dev, bus_list);
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if (dev->subordinate) {
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/* this is a pci-pci bridge, do its devices next */
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next = dev->subordinate->devices.next;
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bus = dev->subordinate;
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} else
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next = dev->bus_list.next;
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/* Run device routines with the device locked */
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device_lock(&dev->dev);
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retval = cb(dev, userdata);
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device_unlock(&dev->dev);
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if (retval)
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break;
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}
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up_read(&pci_bus_sem);
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}
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EXPORT_SYMBOL_GPL(pci_walk_bus);
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EXPORT_SYMBOL(pci_bus_alloc_resource);
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EXPORT_SYMBOL_GPL(pci_bus_add_device);
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EXPORT_SYMBOL(pci_bus_add_devices);
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EXPORT_SYMBOL(pci_enable_bridges);
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