x86/PCI: update MMCONFIG information when hot-plugging PCI host bridges

This patch enhances x86 arch-specific code to update MMCONFIG information
when PCI host bridge hotplug event happens.

Reviewed-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

3 files changed, 92 insertions, 5 deletions

diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index 2bb885afe103..912b54b26d6a 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -13,6 +13,12 @@ struct pci_root_info {
         unsigned int res_num;
         struct resource *res;
         struct pci_sysdata sd;
+#ifdef  CONFIG_PCI_MMCONFIG
+        bool mcfg_added;
+        u16 segment;
+        u8 start_bus;
+        u8 end_bus;
+#endif
 };
 
 static bool pci_use_crs = true;
@@ -119,6 +125,81 @@ void __init pci_acpi_crs_quirks(void)
                pci_use_crs ? "nocrs" : "use_crs");
 }
 
+#ifdef  CONFIG_PCI_MMCONFIG
+static int __devinit check_segment(u16 seg, struct device *dev, char *estr)
+{
+        if (seg) {
+                dev_err(dev,
+                        "%s can't access PCI configuration "
+                        "space under this host bridge.\n",
+                        estr);
+                return -EIO;
+        }
+
+        /*
+         * Failure in adding MMCFG information is not fatal,
+         * just can't access extended configuration space of
+         * devices under this host bridge.
+         */
+        dev_warn(dev,
+                 "%s can't access extended PCI configuration "
+                 "space under this bridge.\n",
+                 estr);
+
+        return 0;
+}
+
+static int __devinit setup_mcfg_map(struct pci_root_info *info,
+                                    u16 seg, u8 start, u8 end,
+                                    phys_addr_t addr)
+{
+        int result;
+        struct device *dev = &info->bridge->dev;
+
+        info->start_bus = start;
+        info->end_bus = end;
+        info->mcfg_added = false;
+
+        /* return success if MMCFG is not in use */
+        if (raw_pci_ext_ops && raw_pci_ext_ops != &pci_mmcfg)
+                return 0;
+
+        if (!(pci_probe & PCI_PROBE_MMCONF))
+                return check_segment(seg, dev, "MMCONFIG is disabled,");
+
+        result = pci_mmconfig_insert(dev, seg, start, end, addr);
+        if (result == 0) {
+                /* enable MMCFG if it hasn't been enabled yet */
+                if (raw_pci_ext_ops == NULL)
+                        raw_pci_ext_ops = &pci_mmcfg;
+                info->mcfg_added = true;
+        } else if (result != -EEXIST)
+                return check_segment(seg, dev,
+                         "fail to add MMCONFIG information,");
+
+        return 0;
+}
+
+static void teardown_mcfg_map(struct pci_root_info *info)
+{
+        if (info->mcfg_added) {
+                pci_mmconfig_delete(info->segment, info->start_bus,
+                                    info->end_bus);
+                info->mcfg_added = false;
+        }
+}
+#else
+static int __devinit setup_mcfg_map(struct pci_root_info *info,
+                                    u16 seg, u8 start, u8 end,
+                                    phys_addr_t addr)
+{
+        return 0;
+}
+static void teardown_mcfg_map(struct pci_root_info *info)
+{
+}
+#endif
+
 static acpi_status
 resource_to_addr(struct acpi_resource *resource,
                         struct acpi_resource_address64 *addr)
@@ -331,8 +412,11 @@ static void __release_pci_root_info(struct pci_root_info *info)
 
         free_pci_root_info_res(info);
 
+        teardown_mcfg_map(info);
+
         kfree(info);
 }
+
 static void release_pci_root_info(struct pci_host_bridge *bridge)
 {
         struct pci_root_info *info = bridge->release_data;
@@ -372,7 +456,7 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
         int domain = root->segment;
         int busnum = root->secondary.start;
         LIST_HEAD(resources);
-        struct pci_bus *bus;
+        struct pci_bus *bus = NULL;
         struct pci_sysdata *sd;
         int node;
 #ifdef CONFIG_ACPI_NUMA
@@ -438,8 +522,11 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
                         x86_pci_root_bus_resources(busnum, &resources);
                 }
 
-                bus = pci_create_root_bus(NULL, busnum, &pci_root_ops, sd,
-                                          &resources);
+                if (!setup_mcfg_map(info, domain, (u8)root->secondary.start,
+                                    (u8)root->secondary.end, root->mcfg_addr))
+                        bus = pci_create_root_bus(NULL, busnum, &pci_root_ops,
+                                                  sd, &resources);
+
                 if (bus) {
                         pci_scan_child_bus(bus);
                         pci_set_host_bridge_release(
diff --git a/arch/x86/pci/mmconfig_32.c b/arch/x86/pci/mmconfig_32.c
index a22785deb50e..db63ac23e3d9 100644
--- a/arch/x86/pci/mmconfig_32.c
+++ b/arch/x86/pci/mmconfig_32.c
@@ -126,7 +126,7 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
         return 0;
 }
 
-static const struct pci_raw_ops pci_mmcfg = {
+const struct pci_raw_ops pci_mmcfg = {
         .read =         pci_mmcfg_read,
         .write =        pci_mmcfg_write,
 };
diff --git a/arch/x86/pci/mmconfig_64.c b/arch/x86/pci/mmconfig_64.c
index ebefea5107a7..c206521fe98e 100644
--- a/arch/x86/pci/mmconfig_64.c
+++ b/arch/x86/pci/mmconfig_64.c
@@ -90,7 +90,7 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
         return 0;
 }
 
-static const struct pci_raw_ops pci_mmcfg = {
+const struct pci_raw_ops pci_mmcfg = {
         .read =         pci_mmcfg_read,
         .write =        pci_mmcfg_write,
 };