[Xen-devel] [PATCH 2 of 2] x86/mm: Disable paging_prep

[Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>]

 xen/arch/x86/mm/p2m.c |  4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)


The only way to page-in a page is now the safe paging_load domctl.
(Unless the page was never paged out in the first place)

Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>
Acked-by: Tim Deegan <tim@xxxxxxx>

diff -r f7c330d5b4b5 -r d5e830891ee2 xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -989,6 +989,10 @@ int p2m_mem_paging_prep(struct domain *d
     /* Allocate a page if the gfn does not have one yet */
     if ( !mfn_valid(mfn) )
     {
+        /* If the user did not provide a buffer, we disallow */
+        ret = -EINVAL;
+        if ( unlikely(user_ptr == NULL) )
+            goto out;
         /* Get a free page */
         ret = -ENOMEM;
         page = alloc_domheap_page(p2m->domain, 0);

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