[PATCH] xen: fix performance decrease with asid assignment

[PATCH] xen: fix performance decrease with asid assignment

[Christoph Egger]

[-- Attachment #1: Type: text/plain, Size: 422 bytes --]


Do not clear asid cleanbit unconditionally. This shaves
off 100 cycles from the VMRUN instruction.

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

-- 
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Einsteinring 24, 85689 Dornach b. Muenchen
Geschaeftsfuehrer: Alberto Bozzo, Andrew Bowd
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

[-- Attachment #2: xen_asid.diff --]
[-- Type: text/plain, Size: 446 bytes --]

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;
 }
 

[-- Attachment #3: Type: text/plain, Size: 126 bytes --]

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel