From: Tim Deegan <tim@xen.org>
Date: Tue, 9 Apr 2013 08:30:33 +0000 (+0200)
Subject: x86: serialize page table population in map_domain_page_global()
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~7051
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=69b0fbfe6036516303a7058b0a182c925c3c56c8;p=xen.git

x86: serialize page table population in map_domain_page_global()

Looking at map_domain_page_global, there doesn't seem to be any locking
preventing two CPUs from populating a page of global-map l1es at the
same time.

Signed-off-by: Tim Deegan <tim@xen.org>
---

diff --git a/xen/arch/x86/domain_page.c b/xen/arch/x86/domain_page.c
index 7421e03358..efda6afd8b 100644
--- a/xen/arch/x86/domain_page.c
+++ b/xen/arch/x86/domain_page.c
@@ -354,9 +354,10 @@ void *map_domain_page_global(unsigned long mfn)
     set_bit(idx, inuse);
     inuse_cursor = idx + 1;
 
+    pl1e = virt_to_xen_l1e(va);
+
     spin_unlock(&globalmap_lock);
 
-    pl1e = virt_to_xen_l1e(va);
     if ( !pl1e )
         return NULL;
     l1e_write(pl1e, l1e_from_pfn(mfn, __PAGE_HYPERVISOR));