For every (IO, MEM, MEM64) bridge window, count the fixed resources of
its children endpoints and children bridge windows:

| <- BAR -> |    | <- child bus fixed_range_hard -> |   | <- fixed BAR -> |
                 | <-            bus's fixed_range_hard                -> |
| <-                       bus's bridge window                         -> |

These ranges will be later used to arrange bridge windows in a way which
covers every immovable BAR as well as the movable ones during hotplug.

Signed-off-by: Sergey Miroshnichenko <s.miroshniche...@yadro.com>
---
 drivers/pci/pci.h       | 14 +++++++
 drivers/pci/probe.c     | 82 +++++++++++++++++++++++++++++++++++++++++
 drivers/pci/setup-bus.c | 17 +++++++++
 include/linux/pci.h     |  6 +++
 4 files changed, 119 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 56b905068ac5..14e3ebe68010 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -364,6 +364,20 @@ static inline bool pci_dev_is_disconnected(const struct 
pci_dev *dev)
        return dev->error_state == pci_channel_io_perm_failure;
 }
 
+static inline int pci_get_bridge_resource_idx(struct resource *r)
+{
+       int idx = 1;
+
+       if (r->flags & IORESOURCE_IO)
+               idx = 0;
+       else if (!(r->flags & IORESOURCE_PREFETCH))
+               idx = 1;
+       else if (r->flags & IORESOURCE_MEM_64)
+               idx = 2;
+
+       return idx;
+}
+
 /* pci_dev priv_flags */
 #define PCI_DEV_ADDED 0
 #define PCI_DEV_IGNORE 1
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 62f4058a001f..70b15654f253 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -551,6 +551,7 @@ void pci_read_bridge_bases(struct pci_bus *child)
 static struct pci_bus *pci_alloc_bus(struct pci_bus *parent)
 {
        struct pci_bus *b;
+       int idx;
 
        b = kzalloc(sizeof(*b), GFP_KERNEL);
        if (!b)
@@ -567,6 +568,11 @@ static struct pci_bus *pci_alloc_bus(struct pci_bus 
*parent)
        if (parent)
                b->domain_nr = parent->domain_nr;
 #endif
+       for (idx = 0; idx < PCI_BRIDGE_RESOURCE_NUM; ++idx) {
+               b->fixed_range_hard[idx].start = (resource_size_t)-1;
+               b->fixed_range_hard[idx].end = 0;
+       }
+
        return b;
 }
 
@@ -3337,6 +3343,81 @@ static void pci_setup_bridges(struct pci_bus *bus)
                pci_setup_bridge(bus);
 }
 
+static void pci_bus_update_fixed_range_hard(struct pci_bus *bus)
+{
+       struct pci_dev *dev;
+       int idx;
+       resource_size_t start, end;
+
+       for (idx = 0; idx < PCI_BRIDGE_RESOURCE_NUM; ++idx) {
+               bus->fixed_range_hard[idx].start = (resource_size_t)-1;
+               bus->fixed_range_hard[idx].end = 0;
+       }
+
+       list_for_each_entry(dev, &bus->devices, bus_list)
+               if (dev->subordinate)
+                       pci_bus_update_fixed_range_hard(dev->subordinate);
+
+       list_for_each_entry(dev, &bus->devices, bus_list) {
+               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;
+
+                       if (r->flags & IORESOURCE_PCI_FIXED) {
+                               idx = pci_get_bridge_resource_idx(r);
+                               start = bus->fixed_range_hard[idx].start;
+                               end = bus->fixed_range_hard[idx].end;
+
+                               if (start > r->start)
+                                       start = r->start;
+                               if (end < r->end)
+                                       end = r->end;
+
+                               if (bus->fixed_range_hard[idx].start != start ||
+                                   bus->fixed_range_hard[idx].end != end) {
+                                       dev_dbg(&bus->dev, "%s: Found fixed 
0x%llx-0x%llx in %s, expand the fixed bridge window %d to 0x%llx-0x%llx\n",
+                                               __func__,
+                                               (unsigned long long)r->start,
+                                               (unsigned long long)r->end,
+                                               dev_name(&dev->dev), idx,
+                                               (unsigned long long)start,
+                                               (unsigned long long)end);
+                                       bus->fixed_range_hard[idx].start = 
start;
+                                       bus->fixed_range_hard[idx].end = end;
+                               }
+                       }
+               }
+
+               if (dev->subordinate) {
+                       struct pci_bus *child = dev->subordinate;
+
+                       for (idx = 0; idx < PCI_BRIDGE_RESOURCE_NUM; ++idx) {
+                               start = bus->fixed_range_hard[idx].start;
+                               end = bus->fixed_range_hard[idx].end;
+
+                               if (start > child->fixed_range_hard[idx].start)
+                                       start = 
child->fixed_range_hard[idx].start;
+                               if (end < child->fixed_range_hard[idx].end)
+                                       end = child->fixed_range_hard[idx].end;
+
+                               if (start < bus->fixed_range_hard[idx].start ||
+                                   end > bus->fixed_range_hard[idx].end) {
+                                       dev_dbg(&bus->dev, "%s: Expand the 
fixed bridge window %d from %s to 0x%llx-0x%llx\n",
+                                               __func__, idx, 
dev_name(&child->dev),
+                                               (unsigned long long)start,
+                                               (unsigned long long)end);
+                                       bus->fixed_range_hard[idx].start = 
start;
+                                       bus->fixed_range_hard[idx].end = end;
+                               }
+                       }
+               }
+       }
+}
+
 static struct pci_dev *pci_find_next_new_device(struct pci_bus *bus)
 {
        struct pci_dev *dev;
@@ -3437,6 +3518,7 @@ unsigned int pci_rescan_bus(struct pci_bus *bus)
                pci_bus_rescan_prepare(root);
 
                max = pci_scan_child_bus(root);
+               pci_bus_update_fixed_range_hard(root);
 
                pci_reassign_root_bus_resources(root);
 
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index c1559a4a8564..a1fd7f3c5ea8 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -879,9 +879,17 @@ static void pbus_size_io(struct pci_bus *bus, 
resource_size_t min_size,
        resource_size_t children_add_size = 0;
        resource_size_t min_align, align;
 
+       resource_size_t fixed_start = bus->fixed_range_hard[0].start;
+       resource_size_t fixed_end = bus->fixed_range_hard[0].end;
+       resource_size_t fixed_size = (fixed_start < fixed_end) ?
+               (fixed_end - fixed_start + 1) : 0;
+
        if (!b_res)
                return;
 
+       if (min_size < fixed_size)
+               min_size = fixed_size;
+
        min_align = window_alignment(bus, IORESOURCE_IO);
        list_for_each_entry(dev, &bus->devices, bus_list) {
                int i;
@@ -990,6 +998,15 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned 
long mask,
        resource_size_t children_add_size = 0;
        resource_size_t children_add_align = 0;
        resource_size_t add_align = 0;
+       bool is_mem64 = (mask & IORESOURCE_MEM_64);
+
+       resource_size_t fixed_start = bus->fixed_range_hard[is_mem64 ? 2 : 
1].start;
+       resource_size_t fixed_end = bus->fixed_range_hard[is_mem64 ? 2 : 1].end;
+       resource_size_t fixed_size = (fixed_start < fixed_end) ?
+               (fixed_end - fixed_start + 1) : 0;
+
+       if (min_size < fixed_size)
+               min_size = fixed_size;
 
        if (!b_res)
                return -ENOSPC;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 26aa59cb6220..7a4d62d84bc1 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -572,6 +572,12 @@ struct pci_bus {
        struct list_head resources;     /* Address space routed to this bus */
        struct resource busn_res;       /* Bus numbers routed to this bus */
 
+       /*
+        * If there are fixed resources in the bridge window, the hard range
+        * contains the lowest and the highest addresses of them.
+        */
+       struct resource fixed_range_hard[PCI_BRIDGE_RESOURCE_NUM];
+
        struct pci_ops  *ops;           /* Configuration access functions */
        struct msi_controller *msi;     /* MSI controller */
        void            *sysdata;       /* Hook for sys-specific extension */
-- 
2.20.1

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