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@citrix.com>
Acked-by: Christoph Egger <Christoph.Egger@amd.com>

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index f6f9874c51580eddde3b91493051ac6cce4087ec..20763b09bb014ae4e5d17b41b2d8feadcbe6ba46 100644 (file)
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1122,8 +1122,8 @@ p2m_get_nestedp2m(struct vcpu *v, uint64_t cr3)
     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;