x86/mem-sharing: Don't leave the altp2m lock held when nominating a page

get_gfn_type_access() internally takes the p2m lock, and nothing ever unlocks
it.  Switch to using the unlocked accessor instead.

This wasn't included in XSA-277 because neither mem-sharing nor altp2m are
supported.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Tamas K Lengyel <tamas@tklengyel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: d6e02850d3b45c9658457214a749cc48097bdef4
master date: 2018-11-22 17:58:46 +0000

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index 84fce187194f9cfa9fe29dfd791427af6b24f954..20a66e025f83054f906999e1092683454d33e697 100644 (file)
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -824,7 +824,8 @@ static int nominate_page(struct domain *d, gfn_t gfn,
             if ( !ap2m )
                 continue;
 
-            amfn = get_gfn_type_access(ap2m, gfn_x(gfn), &ap2mt, &ap2ma, 0, NULL);
+            amfn = __get_gfn_type_access(ap2m, gfn_x(gfn), &ap2mt, &ap2ma,
+                                         0, NULL, false);
             if ( mfn_valid(amfn) && (!mfn_eq(amfn, mfn) || ap2ma != p2ma) )
             {
                 altp2m_list_unlock(d);