# HG changeset patch
# User Jimi Xenidis <jimix@xxxxxxxxxxxxxx>
# Node ID 39d3d1cfe7146a6542a7708bace0ab38f11e48b5
# Parent 2a9c6a23cd1292e9ed361e33d640ce84a6fbdb53
[XEN][POWERPC] Use a bitmap to manage the foreign page area
We needed to be able to dispense pages from the foreign map to Xen VIO
back drivers. I thougth mempool would be an easy way to do this, but
it seems that a bitmap is far easier and simpler to do this with.
Signed-off-by: Jimi Xenidis <jimix@xxxxxxxxxxxxxx>
---
arch/powerpc/platforms/xen/balloon.c | 14 +---
arch/powerpc/platforms/xen/gnttab.c | 100 ++++++++++++++++-------------------
arch/powerpc/platforms/xen/setup.h | 4 -
arch/powerpc/platforms/xen/util.c | 2
4 files changed, 55 insertions(+), 65 deletions(-)
diff -r 2a9c6a23cd12 -r 39d3d1cfe714 arch/powerpc/platforms/xen/balloon.c
--- a/arch/powerpc/platforms/xen/balloon.c Fri Nov 03 16:50:22 2006 -0500
+++ b/arch/powerpc/platforms/xen/balloon.c Wed Nov 08 15:44:19 2006 -0500
@@ -11,22 +11,16 @@ struct page **alloc_empty_pages_and_page
{
struct page *page, **pagevec;
int i;
- int scrub = 0;
pagevec = kmalloc(sizeof(*pagevec) * nr_pages, GFP_KERNEL);
if (pagevec == NULL)
return NULL;
for (i = 0; i < nr_pages; i++) {
- page = alloc_grant_page();
+ page = alloc_foreign_page();
pagevec[i] = page;
-
- if (scrub) {
- void *vaddr;
-
- vaddr = page_address(page);
- scrub_pages(vaddr, 1);
- }
+ /* There is no real page backing us yet so it cannot
+ * be scrubbed */
}
return pagevec;
@@ -40,7 +34,7 @@ void free_empty_pages_and_pagevec(struct
return;
for (i = 0; i < nr_pages; i++) {
- free_grant_page(pagevec[i]);
+ free_foreign_page(pagevec[i]);
}
kfree(pagevec);
diff -r 2a9c6a23cd12 -r 39d3d1cfe714 arch/powerpc/platforms/xen/gnttab.c
--- a/arch/powerpc/platforms/xen/gnttab.c Fri Nov 03 16:50:22 2006 -0500
+++ b/arch/powerpc/platforms/xen/gnttab.c Wed Nov 08 15:44:19 2006 -0500
@@ -2,7 +2,6 @@
#include <linux/config.h>
#include <linux/vmalloc.h>
#include <linux/memory_hotplug.h>
-#include <linux/mempool.h>
#include <xen/gnttab.h>
#include <asm/hypervisor.h>
#include <xen/interface/grant_table.h>
@@ -25,8 +24,9 @@
struct address_space xen_foreign_dummy_mapping;
-static ulong foreign_map_base;
-static ulong foreign_map_end;
+static ulong foreign_map_pfn;
+static ulong foreign_map_pgs;
+static unsigned long *foreign_map_bitmap;
/* hijack _mapcount */
@@ -215,7 +215,9 @@ static void gnttab_post_map_grant_ref(
continue;
}
- BUG_ON(pa < foreign_map_base || pa >= foreign_map_end);
+ BUG_ON(pa < (foreign_map_pfn << PAGE_SHIFT));
+ BUG_ON(pa >= (foreign_map_pfn << PAGE_SHIFT) +
+ (foreign_map_pgs << PAGE_SHIFT));
page = virt_to_page(__va(pa));
@@ -330,9 +332,7 @@ static ulong find_grant_maps(void)
panic("foreign-map is 0x%lx, expect 0x%lx\n",
gm[0], expect);
- foreign_map_base = 1UL << (gm[0] + PAGE_SHIFT);
- foreign_map_end = foreign_map_base + (gm[1] << PAGE_SHIFT);
-
+ foreign_map_pfn = 1UL << gm[0];
return gm[1];
}
@@ -353,40 +353,27 @@ int arch_gnttab_suspend(volatile void __
return 0;
}
-static mempool_t *grant_pool;
-struct page *alloc_grant_page(void)
-{
- void *va;
-
- va = mempool_alloc(grant_pool, GFP_KERNEL);
-
- return virt_to_page(va);
-}
-
-void free_grant_page(struct page *page)
-{
- mempool_free(pfn_to_kaddr(page_to_pfn(page)), grant_pool);
-}
-
-static void *gp_alloc(gfp_t gfp_mask, void *pool_data)
-{
- static ulong count;
- ulong max = (ulong)pool_data;
- void *ret = NULL;
-
- if (count < max) {
- ulong pfn;
-
- pfn = (foreign_map_base >> PAGE_SHIFT) + count;
- ret = pfn_to_kaddr(pfn);
- ++count;
- }
- return ret;
-}
-
-static void gp_free(void *element, void *pool_data)
-{
- BUG();
+struct page *alloc_foreign_page(void)
+{
+ int bit;
+ do {
+ bit = find_first_zero_bit(foreign_map_bitmap,
+ foreign_map_pgs);
+ if (bit >= foreign_map_pgs)
+ return NULL;
+ } while (test_and_set_bit(bit, foreign_map_bitmap) == 1);
+
+ return pfn_to_page(foreign_map_pfn + bit);
+}
+
+void free_foreign_page(struct page *page)
+{
+ int bit = page_to_pfn(page) - foreign_map_pfn;
+
+ BUG_ON(bit < 0);
+ BUG_ON(bit >= foreign_map_pgs);
+
+ clear_bit(bit, foreign_map_bitmap);
}
static void setup_grant_area(void)
@@ -400,25 +387,39 @@ static void setup_grant_area(void)
pgs = find_grant_maps();
setup_foreign_segment();
+ printk("%s: Xen VIO will use a foreign address space of 0x%lx pages\n",
+ __func__, pgs);
+
/* add pages to the zone */
nid = 0;
pgdata = NODE_DATA(nid);
zone = pgdata->node_zones;
- err = __add_pages(zone, foreign_map_base >> PAGE_SHIFT, pgs);
+ err = __add_pages(zone, foreign_map_pfn, pgs);
if (err < 0) {
printk(KERN_EMERG "%s: add_pages(0x%lx, 0x%lx) = %d\n",
- __func__, foreign_map_base >> PAGE_SHIFT, pgs, err);
+ __func__, foreign_map_pfn, pgs, err);
BUG();
}
- /* create a memory pool to manage these pages */
- grant_pool = mempool_create(pgs, gp_alloc, gp_free, (void *)pgs);
- if (grant_pool == NULL) {
- printk(KERN_EMERG "%s: mempool_create(): failed\n", __func__);
+ /* create a bitmap to manage these pages */
+ foreign_map_bitmap = kmalloc(BITS_TO_LONGS(pgs) * sizeof(long),
+ GFP_KERNEL);
+ if (foreign_map_bitmap == NULL) {
+ printk(KERN_EMERG
+ "%s: could not allocate foreign_map_bitmap to "
+ "manage 0x%lx foreign pages\n", __func__, pgs);
BUG();
}
+ /* I'm paranoid so make sure we assign the top bits so we
+ * don't give them away */
+ bitmap_fill(&foreign_map_bitmap[BITS_TO_LONGS(pgs) - 1],
+ BITS_PER_LONG);
+ /* now clear all the real bits */
+ bitmap_zero(foreign_map_bitmap, pgs);
+
+ foreign_map_pgs = pgs;
}
void *arch_gnttab_map(unsigned long *frames)
@@ -439,8 +440,3 @@ void *arch_gnttab_map(unsigned long *fra
return shared;
}
-
-int arch_is_foreign_page(struct page *page)
-{
- return ((page_to_pfn(page) << PAGE_SHIFT) >= foreign_map_base);
-}
diff -r 2a9c6a23cd12 -r 39d3d1cfe714 arch/powerpc/platforms/xen/setup.h
--- a/arch/powerpc/platforms/xen/setup.h Fri Nov 03 16:50:22 2006 -0500
+++ b/arch/powerpc/platforms/xen/setup.h Wed Nov 08 15:44:19 2006 -0500
@@ -22,6 +22,6 @@ static inline u64 jiffies_to_ns(unsigned
#define xen_guest_handle(hnd) ((hnd).p)
-extern struct page *alloc_grant_page(void);
-extern void free_grant_page(struct page *page);
+extern struct page *alloc_foreign_page(void);
+extern void free_foreign_page(struct page *page);
diff -r 2a9c6a23cd12 -r 39d3d1cfe714 arch/powerpc/platforms/xen/util.c
--- a/arch/powerpc/platforms/xen/util.c Fri Nov 03 16:50:22 2006 -0500
+++ b/arch/powerpc/platforms/xen/util.c Wed Nov 08 15:44:19 2006 -0500
@@ -12,7 +12,7 @@ struct vm_struct *alloc_vm_area(unsigned
struct vm_struct *area;
struct page *page;
- page = alloc_grant_page();
+ page = alloc_foreign_page();
if (page == NULL) {
BUG();
return NULL;
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