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[PATCH] xen/x86/hvm: Propagate emulated CR2 writes to the VMCB


  • To: <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Stefano Stabellini <stefano.stabellini@xxxxxxx>
  • Date: Tue, 20 Oct 2026 14:33:15 -0700
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  • Delivery-date: Tue, 20 Oct 2026 21:33:47 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

hvmemul_write_cr() updates guest_cr[2] but, unlike every other writer of
it, doesn't call hvm_update_guest_cr(). On SVM, CR2 is loaded from
the VMCB, so the emulated write never reaches the guest, and the next
VMExit overwrites guest_cr[2] with the stale VMCB value.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
---
 xen/arch/x86/hvm/emulate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index c09ea002ec..cd2831d34b 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2350,6 +2350,7 @@ static int cf_check hvmemul_write_cr(
 
     case 2:
         curr->arch.hvm.guest_cr[2] = val;
+        hvm_update_guest_cr(curr, 2);
         rc = X86EMUL_OKAY;
         break;
 
-- 
2.43.0




 


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