From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Egger <Christoph.Egger@amd.com>
Subject: [PATCH] xen: fix performance decrease with asid
	assignment
Date: Tue, 12 Jun 2012 15:32:52 +0200
Message-ID: <4FD74504.8090407@amd.com>
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Do not clear asid cleanbit unconditionally. This shaves
off 100 cycles from the VMRUN instruction.

Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>

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diff -r 1f466caea5b7 xen/arch/x86/hvm/svm/asid.c
--- a/xen/arch/x86/hvm/svm/asid.c	Fri Jun 08 15:24:29 2012 +0200
+++ b/xen/arch/x86/hvm/svm/asid.c	Tue Jun 12 15:12:48 2012 +0200
@@ -63,7 +63,8 @@ void svm_asid_handle_vmrun(void)
         return;
     }
 
-    vmcb_set_guest_asid(vmcb, p_asid->asid);
+    if (vmcb_get_guest_asid(vmcb) != p_asid->asid)
+        vmcb_set_guest_asid(vmcb, p_asid->asid);
     vmcb->tlb_control = need_flush;
 }
 

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