PCI: pcie: Ensure hotplug ports have a minimum number of resources

In general a BIOS may goof or we may hotplug in a hotplug controller.
In either case the kernel needs to reserve resources for plugging
in more devices in the future instead of creating a minimal resource
assignment.

We already do this for cardbus bridges I am just adding a variant
for pcie bridges.

v2: Make testing for pcie hotplug bridges based on a flag.

    So far we only set the flag for pcie but a header_quirk
    could easily be added for the non-standard pci hotplug
    bridges.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci.c

@@ -41,6 +41,12 @@ int pci_domains_supported = 1;
 unsigned long pci_cardbus_io_size = DEFAULT_CARDBUS_IO_SIZE;
 unsigned long pci_cardbus_mem_size = DEFAULT_CARDBUS_MEM_SIZE;
 
+#define DEFAULT_HOTPLUG_IO_SIZE		(256)
+#define DEFAULT_HOTPLUG_MEM_SIZE	(2*1024*1024)
+/* pci=hpmemsize=nnM,hpiosize=nn can override this */
+unsigned long pci_hotplug_io_size  = DEFAULT_HOTPLUG_IO_SIZE;
+unsigned long pci_hotplug_mem_size = DEFAULT_HOTPLUG_MEM_SIZE;
+
 /**
  * pci_bus_max_busnr - returns maximum PCI bus number of given bus' children
  * @bus: pointer to PCI bus structure to search
@@ -2732,6 +2738,10 @@ static int __init pci_setup(char *str)
 							strlen(str + 19));
 			} else if (!strncmp(str, "ecrc=", 5)) {
 				pcie_ecrc_get_policy(str + 5);
+			} else if (!strncmp(str, "hpiosize=", 9)) {
+				pci_hotplug_io_size = memparse(str + 9, &str);
+			} else if (!strncmp(str, "hpmemsize=", 10)) {
+				pci_hotplug_mem_size = memparse(str + 10, &str);
 			} else {
 				printk(KERN_ERR "PCI: Unknown option `%s'\n",
 						str);

drivers/pci/probe.c

@@ -697,6 +697,23 @@ static void set_pcie_port_type(struct pci_dev *pdev)
 	pdev->pcie_type = (reg16 & PCI_EXP_FLAGS_TYPE) >> 4;
 }
 
+static void set_pcie_hotplug_bridge(struct pci_dev *pdev)
+{
+	int pos;
+	u16 reg16;
+	u32 reg32;
+
+	pos = pci_find_capability(pdev, PCI_CAP_ID_EXP);
+	if (!pos)
+		return;
+	pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, &reg16);
+	if (!(reg16 & PCI_EXP_FLAGS_SLOT))
+		return;
+	pci_read_config_dword(pdev, pos + PCI_EXP_SLTCAP, &reg32);
+	if (reg32 & PCI_EXP_SLTCAP_HPC)
+		pdev->is_hotplug_bridge = 1;
+}
+
 #define LEGACY_IO_RESOURCE	(IORESOURCE_IO | IORESOURCE_PCI_FIXED)
 
 /**
@@ -804,6 +821,7 @@ int pci_setup_device(struct pci_dev *dev)
 		pci_read_irq(dev);
 		dev->transparent = ((dev->class & 0xff) == 1);
 		pci_read_bases(dev, 2, PCI_ROM_ADDRESS1);
+		set_pcie_hotplug_bridge(dev);
 		break;
 
 	case PCI_HEADER_TYPE_CARDBUS:		    /* CardBus bridge header */

drivers/pci/setup-bus.c

@@ -309,7 +309,7 @@ static struct resource *find_free_bus_resource(struct pci_bus *bus, unsigned lon
    since these windows have 4K granularity and the IO ranges
    of non-bridge PCI devices are limited to 256 bytes.
    We must be careful with the ISA aliasing though. */
-static void pbus_size_io(struct pci_bus *bus)
+static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size)
 {
 	struct pci_dev *dev;
 	struct resource *b_res = find_free_bus_resource(bus, IORESOURCE_IO);
@@ -336,6 +336,8 @@ static void pbus_size_io(struct pci_bus *bus)
 				size1 += r_size;
 		}
 	}
+	if (size < min_size)
+		size = min_size;
 /* To be fixed in 2.5: we should have sort of HAVE_ISA
    flag in the struct pci_bus. */
 #if defined(CONFIG_ISA) || defined(CONFIG_EISA)
@@ -354,7 +356,8 @@ static void pbus_size_io(struct pci_bus *bus)
 
 /* Calculate the size of the bus and minimal alignment which
    guarantees that all child resources fit in this size. */
-static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, unsigned long type)
+static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
+			 unsigned long type, resource_size_t min_size)
 {
 	struct pci_dev *dev;
 	resource_size_t min_align, align, size;
@@ -404,6 +407,8 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, unsigned long
 			mem64_mask &= r->flags & IORESOURCE_MEM_64;
 		}
 	}
+	if (size < min_size)
+		size = min_size;
 
 	align = 0;
 	min_align = 0;
@@ -483,6 +488,7 @@ void __ref pci_bus_size_bridges(struct pci_bus *bus)
 {
 	struct pci_dev *dev;
 	unsigned long mask, prefmask;
+	resource_size_t min_mem_size = 0, min_io_size = 0;
 
 	list_for_each_entry(dev, &bus->devices, bus_list) {
 		struct pci_bus *b = dev->subordinate;
@@ -512,8 +518,12 @@ void __ref pci_bus_size_bridges(struct pci_bus *bus)
 
 	case PCI_CLASS_BRIDGE_PCI:
 		pci_bridge_check_ranges(bus);
+		if (bus->self->is_hotplug_bridge) {
+			min_io_size  = pci_hotplug_io_size;
+			min_mem_size = pci_hotplug_mem_size;
+		}
 	default:
-		pbus_size_io(bus);
+		pbus_size_io(bus, min_io_size);
 		/* If the bridge supports prefetchable range, size it
 		   separately. If it doesn't, or its prefetchable window
 		   has already been allocated by arch code, try
@@ -521,9 +531,11 @@ void __ref pci_bus_size_bridges(struct pci_bus *bus)
 		   resources. */
 		mask = IORESOURCE_MEM;
 		prefmask = IORESOURCE_MEM | IORESOURCE_PREFETCH;
-		if (pbus_size_mem(bus, prefmask, prefmask))
+		if (pbus_size_mem(bus, prefmask, prefmask, min_mem_size))
 			mask = prefmask; /* Success, size non-prefetch only. */
-		pbus_size_mem(bus, mask, IORESOURCE_MEM);
+		else
+			min_mem_size += min_mem_size;
+		pbus_size_mem(bus, mask, IORESOURCE_MEM, min_mem_size);
 		break;
 	}
 }

include/linux/pci.h

@@ -278,6 +278,7 @@ struct pci_dev {
 	unsigned int	is_physfn:1;
 	unsigned int	is_virtfn:1;
 	unsigned int	reset_fn:1;
+	unsigned int    is_hotplug_bridge:1;
 	pci_dev_flags_t dev_flags;
 	atomic_t	enable_cnt;	/* pci_enable_device has been called */
 
@@ -1245,6 +1246,9 @@ extern int pci_pci_problems;
 extern unsigned long pci_cardbus_io_size;
 extern unsigned long pci_cardbus_mem_size;
 
+extern unsigned long pci_hotplug_io_size;
+extern unsigned long pci_hotplug_mem_size;
+
 int pcibios_add_platform_entries(struct pci_dev *dev);
 void pcibios_disable_device(struct pci_dev *dev);
 int pcibios_set_pcie_reset_state(struct pci_dev *dev,