diff mbox series

[v2,6/9] x86/HVM: relax shadow mode check in hvm_set_cr3()

Message ID 4e44e6e6-ca5c-dd93-2407-f92f6a82b053@suse.com (mailing list archive)
State New, archived
Headers show
Series XSA-292 follow-up | expand

Commit Message

Jan Beulich Sept. 17, 2019, 6:16 a.m. UTC 
There's no need to re-obtain a page reference if only bits not affecting
the address change.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Comments

Andrew Cooper Sept. 17, 2019, 7:37 p.m. UTC | #1 
On 17/09/2019 07:16, Jan Beulich wrote:
> There's no need to re-obtain a page reference if only bits not affecting
> the address change.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
diff mbox series

Patch

--- 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);