From: Keir Fraser <keir@xensource.com>
Date: Wed, 31 Oct 2007 09:21:37 +0000 (+0000)
Subject: Add boot parameter 'pci-mem-align' to page-align PCI memory regions.
X-Git-Tag: xen-3.2.0~21^2^2~28^2^2~22^2^2~9^2~12^2
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=49bfe589c439bfe8a785a988e6c19d7ce25afea2;p=xenclient%2Fkernel.git

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@neocleus.com>
Signed-off-by: Keir Fraser <keir@xensource.com>
---

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 5f7db9d2..6036149d 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -17,6 +17,8 @@
 
 #include "pci.h"
 
+extern int pci_mem_align;
+
 /**
  * pci_bus_alloc_resource - allocate a resource from a parent bus
  * @bus: PCI bus
@@ -44,6 +46,11 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
 
 	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];
 		if (!r)
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 60b31acb..7b1721cb 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -23,6 +23,40 @@
 #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
  * PCI scanning code to "skip" this now blacklisted device.