[Xen-changelog] [xen-unstable] Nested p2m: remove bogus check of CR3 value.

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Tim Deegan <Tim.Deegan@xxxxxxxxxx>
# Date 1309426014 -3600
# Node ID e0d030d17e39ba57f563ae3f95bb410532ed1909
# Parent  970797044f52db4b4a2ea7b0fe3092e08876e84d
Nested p2m: remove bogus check of CR3 value.

0 is a valid CR3 value; CR3_EADDR isn't but there's nothing stopping a
guest from putting it in its VMCB.  The special case was broken anyway
since AFAICT "p2m->cr3" is a nester-cr3 (i.e. p2m-table) value and
guest_cr[3] is an actual-cr3 (pagetable) value.

Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Acked-by: Christoph Egger <Christoph.Egger@xxxxxxx>
---


diff -r 970797044f52 -r e0d030d17e39 xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c     Thu Jun 30 10:26:54 2011 +0100
+++ b/xen/arch/x86/mm/p2m.c     Thu Jun 30 10:26:54 2011 +0100
@@ -1122,8 +1122,8 @@
     struct p2m_domain *p2m;
     int i;
 
-    if (cr3 == 0 || cr3 == CR3_EADDR)
-        cr3 = v->arch.hvm_vcpu.guest_cr[3];
+    /* Mask out low bits; this avoids collisions with CR3_EADDR */
+    cr3 &= ~(0xfffull);
 
     if (nv->nv_flushp2m && nv->nv_p2m) {
         nv->nv_p2m = NULL;

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