[Xen-changelog] [xen staging] x86/HVM: relax shadow mode check in hvm_set_cr3()

[patchbot@xxxxxxx]

commit 24c704fb0cd621ffb9e8c5b97fcb83469bd019f7
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Sep 18 15:19:08 2019 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Sep 18 15:19:08 2019 +0200

    x86/HVM: relax shadow mode check in hvm_set_cr3()
    
    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>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 977934a56c..fdb1e17f59 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2323,7 +2323,7 @@ int hvm_set_cr3(unsigned long value, bool may_defer)
     }
 
     if ( hvm_paging_enabled(v) && !paging_mode_hap(v->domain) &&
-         (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);
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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