[Xen-devel] [PATCH 05/12] x86/xen: require ballooned pages for grant maps

[David Vrabel <david.vrabel@xxxxxxxxxx>]

From: Jenny Herbert <jennifer.herbert@xxxxxxxxxx>

Ballooned pages are always used for grant maps which means the
original frame does not need to be saved in page->index nor restored
after the grant unmap.

This allows the workaround in netback for the conflicting use of the
(unionized) page->index and page->pfmemalloc to be removed.

Signed-off-by: Jenny Herbert <jennifer.herbert@xxxxxxxxxx>
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
 arch/x86/xen/p2m.c                |    5 +++--
 drivers/net/xen-netback/netback.c |    6 ------
 2 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 8f34ed4..0d70814 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -682,9 +682,10 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref 
*map_ops,
                pfn = page_to_pfn(pages[i]);
 
                WARN_ON(PagePrivate(pages[i]));
+               WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be 
ballooned");
+
                SetPagePrivate(pages[i]);
                set_page_private(pages[i], mfn);
-               pages[i]->index = pfn_to_mfn(pfn);
 
                if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
                        ret = -ENOMEM;
@@ -718,7 +719,7 @@ int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref 
*unmap_ops,
                set_page_private(pages[i], INVALID_P2M_ENTRY);
                WARN_ON(!PagePrivate(pages[i]));
                ClearPagePrivate(pages[i]);
-               set_phys_to_machine(pfn, pages[i]->index);
+               set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
        }
        if (kunmap_ops)
                ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
diff --git a/drivers/net/xen-netback/netback.c 
b/drivers/net/xen-netback/netback.c
index 908e65e..6441318 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1241,12 +1241,6 @@ static void xenvif_fill_frags(struct xenvif_queue 
*queue, struct sk_buff *skb)
                /* Take an extra reference to offset network stack's put_page */
                get_page(queue->mmap_pages[pending_idx]);
        }
-       /* FIXME: __skb_fill_page_desc set this to true because page->pfmemalloc
-        * overlaps with "index", and "mapping" is not set. I think mapping
-        * should be set. If delivered to local stack, it would drop this
-        * skb in sk_filter unless the socket has the right to use it.
-        */
-       skb->pfmemalloc = false;
 }
 
 static int xenvif_get_extras(struct xenvif_queue *queue,
-- 
1.7.10.4


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