patches/kernel/0007-PCI-Reinstate-PCI-Coalesce-host-bridge-contiguous-ap.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Kai-Heng Feng <kai.heng.feng@canonical.com>
   3 Date: Tue, 13 Jul 2021 20:50:07 +0800
   4 Subject: [PATCH] PCI: Reinstate "PCI: Coalesce host bridge contiguous
   5  apertures"
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
   8 Content-Transfer-Encoding: 8bit
   9
  10 Built-in graphics on HP EliteDesk 805 G6 doesn't work because graphics
  11 can't get the BAR it needs:
  12   pci_bus 0000:00: root bus resource [mem 0x10020200000-0x100303fffff window]
  13   pci_bus 0000:00: root bus resource [mem 0x10030400000-0x100401fffff window]
  14
  15   pci 0000:00:08.1:   bridge window [mem 0xd2000000-0xd23fffff]
  16   pci 0000:00:08.1:   bridge window [mem 0x10030000000-0x100401fffff 64bit pref]
  17   pci 0000:00:08.1: can't claim BAR 15 [mem 0x10030000000-0x100401fffff 64bit pref]: no compatible bridge window
  18   pci 0000:00:08.1: [mem 0x10030000000-0x100401fffff 64bit pref] clipped to [mem 0x10030000000-0x100303fffff 64bit pref]
  19   pci 0000:00:08.1:   bridge window [mem 0x10030000000-0x100303fffff 64bit pref]
  20   pci 0000:07:00.0: can't claim BAR 0 [mem 0x10030000000-0x1003fffffff 64bit pref]: no compatible bridge window
  21   pci 0000:07:00.0: can't claim BAR 2 [mem 0x10040000000-0x100401fffff 64bit pref]: no compatible bridge window
  22
  23 However, the root bus has two contiguous apertures that can contain the
  24 child resource requested.
  25
  26 Coalesce contiguous apertures so we can allocate from the entire contiguous
  27 region.
  28
  29 This is the second take of commit 65db04053efe ("PCI: Coalesce host
  30 bridge contiguous apertures"). The original approach sorts the apertures
  31 by address, but that makes NVMe stop working on QEMU ppc:sam460ex:
  32   PCI host bridge to bus 0002:00
  33   pci_bus 0002:00: root bus resource [io  0x0000-0xffff]
  34   pci_bus 0002:00: root bus resource [mem 0xd80000000-0xdffffffff] (bus address [0x80000000-0xffffffff])
  35   pci_bus 0002:00: root bus resource [mem 0xc0ee00000-0xc0eefffff] (bus address [0x00000000-0x000fffff])
  36
  37 After the offending commit:
  38   PCI host bridge to bus 0002:00
  39   pci_bus 0002:00: root bus resource [io  0x0000-0xffff]
  40   pci_bus 0002:00: root bus resource [mem 0xc0ee00000-0xc0eefffff] (bus address [0x00000000-0x000fffff])
  41   pci_bus 0002:00: root bus resource [mem 0xd80000000-0xdffffffff] (bus address [0x80000000-0xffffffff])
  42
  43 Since the apertures on HP EliteDesk 805 G6 are already in ascending
  44 order, doing a precautious sorting is not necessary.
  45
  46 Remove the sorting part to avoid the regression on ppc:sam460ex.
  47
  48 Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212013
  49 Cc: Guenter Roeck <linux@roeck-us.net>
  50 Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
  51 Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
  52 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  53 ---
  54  drivers/pci/probe.c | 31 +++++++++++++++++++++++++++----
  55  1 file changed, 27 insertions(+), 4 deletions(-)
  56
  57 diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
  58 index 275204646c68..944c35d87258 100644
  59 --- a/drivers/pci/probe.c
  60 +++ b/drivers/pci/probe.c
  61 @@ -877,11 +877,11 @@ static void pci_set_bus_msi_domain(struct pci_bus *bus)
  62  static int pci_register_host_bridge(struct pci_host_bridge *bridge)
  63  {
  64         struct device *parent = bridge->dev.parent;
  65 -       struct resource_entry *window, *n;
  66 +       struct resource_entry *window, *next, *n;
  67         struct pci_bus *bus, *b;
  68 -       resource_size_t offset;
  69 +       resource_size_t offset, next_offset;
  70         LIST_HEAD(resources);
  71 -       struct resource *res;
  72 +       struct resource *res, *next_res;
  73         char addr[64], *fmt;
  74         const char *name;
  75         int err;
  76 @@ -961,11 +961,34 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
  77         if (nr_node_ids > 1 && pcibus_to_node(bus) == NUMA_NO_NODE)
  78                 dev_warn(&bus->dev, "Unknown NUMA node; performance will be reduced\n");
  79
  80 +       /* Coalesce contiguous windows */
  81 +       resource_list_for_each_entry_safe(window, n, &resources) {
  82 +               if (list_is_last(&window->node, &resources))
  83 +                       break;
  84 +
  85 +               next = list_next_entry(window, node);
  86 +               offset = window->offset;
  87 +               res = window->res;
  88 +               next_offset = next->offset;
  89 +               next_res = next->res;
  90 +
  91 +               if (res->flags != next_res->flags || offset != next_offset)
  92 +                       continue;
  93 +
  94 +               if (res->end + 1 == next_res->start) {
  95 +                       next_res->start = res->start;
  96 +                       res->flags = res->start = res->end = 0;
  97 +               }
  98 +       }
  99 +
 100         /* Add initial resources to the bus */
 101         resource_list_for_each_entry_safe(window, n, &resources) {
 102 -               list_move_tail(&window->node, &bridge->windows);
 103                 offset = window->offset;
 104                 res = window->res;
 105 +               if (!res->end)
 106 +                       continue;
 107 +
 108 +               list_move_tail(&window->node, &bridge->windows);
 109
 110                 if (res->flags & IORESOURCE_BUS)
 111                         pci_bus_insert_busn_res(bus, bus->number, res->end);