From: Keir Fraser <keir@xen.org>
Date: Fri, 20 May 2011 08:07:54 +0000 (+0100)
Subject: nestedsvm: reduce TLB flushes
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~10342
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success//%22http:/www.example.com/cgi/success/?a=commitdiff_plain;h=c33a0b24c1f04d45d79c0b5657ecb25677dd1fb2;p=xen.git

nestedsvm: reduce TLB flushes

Reduce TLB flushes:
1. When we update the cr3 during VMRUN/VMEXIT emulation
    we toggle between n1asid and n2asid forth and back
    => no TLB flush needed
2. Only flush n1asid or n2asid depending on vcpu guest mode
    and not both unconditionally.

Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
Signed-off-by: Keir Fraser <keir@xen.org>
---

diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 8b1557b8ca..55d76323f3 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -454,7 +454,7 @@ static void svm_update_guest_cr(struct vcpu *v, unsigned int cr)
         if ( !nestedhvm_enabled(v->domain) )
             hvm_asid_flush_vcpu(v);
         else if ( nestedhvm_vmswitch_in_progress(v) )
-            ; /* We toggle between n1asid/n2asid -> no flush required. */
+            ; /* CR3 switches during VMRUN/VMEXIT do not flush the TLB. */
         else
             hvm_asid_flush_vcpu_asid(
                 nestedhvm_vcpu_in_guestmode(v)