[Xen-changelog] [linux-2.6.18-xen] Add boot parameter 'pci-mem-align' to page-align PCI memory regions.

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxxxxxxxx>
# Date 1193822497 0
# Node ID ba69bacc7e8a28ec3aa7bcec0dbd21a3be2db2eb
# Parent  71a5313e13f5d99b1b550b1b5f1c0198fc4c9a70
Add boot parameter 'pci-mem-align' to page-align PCI memory regions.

In PCI pass-through the mmio resources are mapped/translated from pfns
to mfns (page size), so mmio resources should be at least
page-aligned.

Signed-off-by: Barak Fargoun <barak@xxxxxxxxxxxx>
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 drivers/pci/bus.c    |    7 +++++++
 drivers/pci/quirks.c |   34 ++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff -r 71a5313e13f5 -r ba69bacc7e8a drivers/pci/bus.c
--- a/drivers/pci/bus.c Tue Oct 30 17:35:21 2007 +0000
+++ b/drivers/pci/bus.c Wed Oct 31 09:21:37 2007 +0000
@@ -16,6 +16,8 @@
 #include <linux/init.h>
 
 #include "pci.h"
+
+extern int pci_mem_align;
 
 /**
  * pci_bus_alloc_resource - allocate a resource from a parent bus
@@ -43,6 +45,11 @@ pci_bus_alloc_resource(struct pci_bus *b
        int i, ret = -ENOMEM;
 
        type_mask |= IORESOURCE_IO | IORESOURCE_MEM;
+
+       /* If the boot parameter 'pci-mem-align' was specified then we need to 
+          align the memory addresses, at page size alignment. */
+       if (pci_mem_align && (align < (PAGE_SIZE-1)))
+               align = PAGE_SIZE - 1;
 
        for (i = 0; i < PCI_BUS_NUM_RESOURCES; i++) {
                struct resource *r = bus->resource[i];
diff -r 71a5313e13f5 -r ba69bacc7e8a drivers/pci/quirks.c
--- a/drivers/pci/quirks.c      Tue Oct 30 17:35:21 2007 +0000
+++ b/drivers/pci/quirks.c      Wed Oct 31 09:21:37 2007 +0000
@@ -22,6 +22,40 @@
 #include <linux/delay.h>
 #include <linux/acpi.h>
 #include "pci.h"
+
+/* A global flag which signals if we should page-align PCI mem windows. */
+int pci_mem_align = 0;
+
+static int __init set_pci_mem_align(char *str)
+{
+       pci_mem_align = 1;
+       return 1;
+}
+__setup("pci-mem-align", set_pci_mem_align);
+
+/* This quirk function enables us to force all memory resources which are 
+ * assigned to PCI devices, to be page-aligned.
+ */
+static void __devinit quirk_align_mem_resources(struct pci_dev *dev)
+{
+       int i;
+       struct resource *r;
+       resource_size_t old_start;
+
+       if (!pci_mem_align)
+               return;
+
+       for (i=0; i < DEVICE_COUNT_RESOURCE; i++) {
+               r = &dev->resource[i];
+               if ((r == NULL) || !(r->flags & IORESOURCE_MEM))
+                       continue;
+
+               old_start = r->start;
+               r->start = (r->start + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
+               r->end = r->end - (old_start - r->start);
+       }
+}
+DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID, quirk_align_mem_resources);
 
 /* The Mellanox Tavor device gives false positive parity errors
  * Mark this device with a broken_parity_status, to allow

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