KVM: PPC: Book3S: PR: No isync in slbie path

While messing around with the SLBs we're running in real mode. The
entry to guest space goes through rfid, which is context synchronizing,
so there's no need to manually synchronize anything through isync.

With this patch and a simple priviledged SPR access loop guest, I get
a speed bump from 2035607 to 2181301 exits per second.

Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/arch/powerpc/kvm/book3s_64_slb.S b/arch/powerpc/kvm/book3s_64_slb.S
index f2e6e48ea463c9cdb404bb384ce672244f0e795f..56b983e7b7380c88a4199d68dc97fb2a6a0ec985 100644 (file)
--- a/arch/powerpc/kvm/book3s_64_slb.S
+++ b/arch/powerpc/kvm/book3s_64_slb.S
@@ -90,8 +90,6 @@ slb_exit_skip_ ## num:
        or      r10, r10, r12
        slbie   r10
 
-       isync
-
        /* Fill SLB with our shadow */
 
        lbz     r12, SVCPU_SLB_MAX(r3)