From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Fri, 1 Feb 2019 10:28:45 +0000 (+0100)
Subject: x86/mem-sharing: Don't leave the altp2m lock held when nominating a page
X-Git-Tag: RELEASE-4.11.2~104
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=7d1bd985ebd4c1473c4dfd50b6d3a33c8e1b1a93;p=people%2Fdwmw2%2Fxen.git

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 fad8a9df13..536262d9b7 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -819,7 +819,8 @@ 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);