PCI: allow assignment of memory resources with a specified alignment
This patch allows memory resources to be assigned with a specified
alignment at boot-time or run-time. The patch is useful when we use PCI
pass-through, because page-aligned memory resources are required to
securely share PCI resources with guest drivers.
If you want to assign the resource at boot time, please set
"pci=resource_alignment=" boot parameter.
This is format of "pci=resource_alignment=" boot parameter:
[<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
Specifies alignment and device to reassign
aligned memory resources.
If <order of align> is not specified, PAGE_SIZE is
used as alignment.
PCI-PCI bridge can be specified, if resource
windows need to be expanded.
This is example:
pci=resource_alignment=20@07:00.0;18@0f:00.0;00:1d.7
If you want to assign the resource at run-time, please set
"/sys/bus/pci/resource_alignment" file, and hot-remove the device and
hot-add the device. For this purpose, fakephp or PCI hotplug interfaces
can be used.
The format of "/sys/bus/pci/resource_alignment" file is the same with
boot parameter. You can use "," instead of ";".
For example:
# cd /sys/bus/pci
# echo -n 20@12:00.0 > resource_alignment
# echo 1 > devices/0000:12:00.0/remove
# echo 1 > rescan
Reviewed-by: Alex Chiang <achiang@hp.com>
Reviewed-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Yuji Shimada <shimada-yxb@necst.nec.co.jp>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 8310dc2..a35a8b2 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -20,6 +20,8 @@
#include <linux/pm_wakeup.h>
#include <linux/interrupt.h>
#include <asm/dma.h> /* isa_dma_bridge_buggy */
+#include <linux/device.h>
+#include <asm/setup.h>
#include "pci.h"
unsigned int pci_pm_d3_delay = PCI_PM_D3_WAIT;
@@ -2370,6 +2372,121 @@
return 0;
}
+#define RESOURCE_ALIGNMENT_PARAM_SIZE COMMAND_LINE_SIZE
+static char resource_alignment_param[RESOURCE_ALIGNMENT_PARAM_SIZE] = {0};
+spinlock_t resource_alignment_lock = SPIN_LOCK_UNLOCKED;
+
+/**
+ * pci_specified_resource_alignment - get resource alignment specified by user.
+ * @dev: the PCI device to get
+ *
+ * RETURNS: Resource alignment if it is specified.
+ * Zero if it is not specified.
+ */
+resource_size_t pci_specified_resource_alignment(struct pci_dev *dev)
+{
+ int seg, bus, slot, func, align_order, count;
+ resource_size_t align = 0;
+ char *p;
+
+ spin_lock(&resource_alignment_lock);
+ p = resource_alignment_param;
+ while (*p) {
+ count = 0;
+ if (sscanf(p, "%d%n", &align_order, &count) == 1 &&
+ p[count] == '@') {
+ p += count + 1;
+ } else {
+ align_order = -1;
+ }
+ if (sscanf(p, "%x:%x:%x.%x%n",
+ &seg, &bus, &slot, &func, &count) != 4) {
+ seg = 0;
+ if (sscanf(p, "%x:%x.%x%n",
+ &bus, &slot, &func, &count) != 3) {
+ /* Invalid format */
+ printk(KERN_ERR "PCI: Can't parse resource_alignment parameter: %s\n",
+ p);
+ break;
+ }
+ }
+ p += count;
+ if (seg == pci_domain_nr(dev->bus) &&
+ bus == dev->bus->number &&
+ slot == PCI_SLOT(dev->devfn) &&
+ func == PCI_FUNC(dev->devfn)) {
+ if (align_order == -1) {
+ align = PAGE_SIZE;
+ } else {
+ align = 1 << align_order;
+ }
+ /* Found */
+ break;
+ }
+ if (*p != ';' && *p != ',') {
+ /* End of param or invalid format */
+ break;
+ }
+ p++;
+ }
+ spin_unlock(&resource_alignment_lock);
+ return align;
+}
+
+/**
+ * pci_is_reassigndev - check if specified PCI is target device to reassign
+ * @dev: the PCI device to check
+ *
+ * RETURNS: non-zero for PCI device is a target device to reassign,
+ * or zero is not.
+ */
+int pci_is_reassigndev(struct pci_dev *dev)
+{
+ return (pci_specified_resource_alignment(dev) != 0);
+}
+
+ssize_t pci_set_resource_alignment_param(const char *buf, size_t count)
+{
+ if (count > RESOURCE_ALIGNMENT_PARAM_SIZE - 1)
+ count = RESOURCE_ALIGNMENT_PARAM_SIZE - 1;
+ spin_lock(&resource_alignment_lock);
+ strncpy(resource_alignment_param, buf, count);
+ resource_alignment_param[count] = '\0';
+ spin_unlock(&resource_alignment_lock);
+ return count;
+}
+
+ssize_t pci_get_resource_alignment_param(char *buf, size_t size)
+{
+ size_t count;
+ spin_lock(&resource_alignment_lock);
+ count = snprintf(buf, size, "%s", resource_alignment_param);
+ spin_unlock(&resource_alignment_lock);
+ return count;
+}
+
+static ssize_t pci_resource_alignment_show(struct bus_type *bus, char *buf)
+{
+ return pci_get_resource_alignment_param(buf, PAGE_SIZE);
+}
+
+static ssize_t pci_resource_alignment_store(struct bus_type *bus,
+ const char *buf, size_t count)
+{
+ return pci_set_resource_alignment_param(buf, count);
+}
+
+BUS_ATTR(resource_alignment, 0644, pci_resource_alignment_show,
+ pci_resource_alignment_store);
+
+static int __init pci_resource_alignment_sysfs_init(void)
+{
+ return bus_create_file(&pci_bus_type,
+ &bus_attr_resource_alignment);
+}
+
+late_initcall(pci_resource_alignment_sysfs_init);
+
static void __devinit pci_no_domains(void)
{
#ifdef CONFIG_PCI_DOMAINS
@@ -2418,6 +2535,9 @@
pci_cardbus_io_size = memparse(str + 9, &str);
} else if (!strncmp(str, "cbmemsize=", 10)) {
pci_cardbus_mem_size = memparse(str + 10, &str);
+ } else if (!strncmp(str, "resource_alignment=", 19)) {
+ pci_set_resource_alignment_param(str + 19,
+ strlen(str + 19));
} else {
printk(KERN_ERR "PCI: Unknown option `%s'\n",
str);