WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] [PATCH 2/3] xen-balloon: Add interface to retrieve ballooned

To: Ian.Campbell@xxxxxxxxxx
Subject: [Xen-devel] [PATCH 2/3] xen-balloon: Add interface to retrieve ballooned pages
From: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
Date: Mon, 7 Mar 2011 13:06:47 -0500
Cc: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, konrad.wilk@xxxxxxxxxx
Delivery-date: Mon, 07 Mar 2011 10:09:15 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <1299521208-8531-1-git-send-email-dgdegra@xxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <1299521208-8531-1-git-send-email-dgdegra@xxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Pages that have been ballooned are useful for other Xen drivers doing
grant table actions, because these pages have valid struct page/PFNs but
have no valid MFN so are available for remapping.

Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
---
 drivers/xen/balloon.c |   54 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/xen/balloon.h |    3 ++
 2 files changed, 57 insertions(+), 0 deletions(-)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index b0a7a92..be53596 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -328,6 +328,60 @@ void balloon_set_new_target(unsigned long target)
 }
 EXPORT_SYMBOL_GPL(balloon_set_new_target);
 
+/**
+ * get_ballooned_pages - get pages that have been ballooned out
+ * @nr_pages: Number of pages to get
+ * @pages: pages returned
+ * @force: Try to balloon out more pages if needed
+ * @return number of pages retrieved
+ */
+int get_ballooned_pages(int nr_pages, struct page** pages, int force)
+{
+       int rv = 0;
+       struct page* page;
+       mutex_lock(&balloon_mutex);
+       /* Pages are pulled off the back of the queue to prefer highmem */
+       while (rv < nr_pages) {
+               if (list_empty(&ballooned_pages)) {
+                       if (!force)
+                               break;
+                       if (decrease_reservation(nr_pages - rv))
+                               force = 0;
+               } else {
+                       page = list_entry(ballooned_pages.prev,
+                               struct page, lru);
+                       list_del(&page->lru);
+                       pages[rv++] = page;
+               }
+       }
+       mutex_unlock(&balloon_mutex);
+       return rv;
+}
+EXPORT_SYMBOL(get_ballooned_pages);
+
+/**
+ * put_ballooned_pages - return pages retrieved with get_ballooned_pages
+ * @nr_pages: Number of pages
+ * @pages: pages to return
+ */
+void put_ballooned_pages(int nr_pages, struct page** pages)
+{
+       int i;
+
+       mutex_lock(&balloon_mutex);
+
+       for (i = 0; i < nr_pages; i++) {
+               if (PageHighMem(pages[i])) {
+                       list_add_tail(&pages[i]->lru, &ballooned_pages);
+               } else {
+                       list_add(&pages[i]->lru, &ballooned_pages);
+               }
+       }
+
+       mutex_unlock(&balloon_mutex);
+}
+EXPORT_SYMBOL(put_ballooned_pages);
+
 static int __init balloon_init(void)
 {
        unsigned long pfn, nr_pages, extra_pfn_end;
diff --git a/include/xen/balloon.h b/include/xen/balloon.h
index b2b7c21..5fc25fa 100644
--- a/include/xen/balloon.h
+++ b/include/xen/balloon.h
@@ -19,3 +19,6 @@ struct balloon_stats {
 extern struct balloon_stats balloon_stats;
 
 void balloon_set_new_target(unsigned long target);
+
+int get_ballooned_pages(int nr_pages, struct page** pages, int force);
+void put_ballooned_pages(int nr_pages, struct page** pages);
-- 
1.7.3.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel