[Xen-devel] [PATCH v2 6/9] x86/HVM: relax shadow mode check in hvm_set_cr3()

[Jan Beulich <jbeulich@xxxxxxxx>]

There's no need to re-obtain a page reference if only bits not affecting
the address change.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2325,7 +2325,7 @@ int hvm_set_cr3(unsigned long value, boo
     }
 
     if ( hvm_paging_enabled(v) && !paging_mode_hap(currd) &&
-         (value != v->arch.hvm.guest_cr[3]) )
+         ((value ^ v->arch.hvm.guest_cr[3]) >> PAGE_SHIFT) )
     {
         /* Shadow-mode CR3 change. Check PDBR and update refcounts. */
         HVM_DBG_LOG(DBG_LEVEL_VMMU, "CR3 value = %lx", value);


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