Patchwork [2/2] KVM: PPC: Book3S: PR: No isync in slbie path

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Submitter Alexander Graf
Date April 25, 2012, 12:38 p.m.
Message ID <1335357502-30113-2-git-send-email-agraf@suse.de>
Download mbox | patch
Permalink /patch/154902/
State New
Headers show

Comments

Alexander Graf - April 25, 2012, 12:38 p.m.
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>
---
 arch/powerpc/kvm/book3s_64_slb.S |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

Patch

diff --git a/arch/powerpc/kvm/book3s_64_slb.S b/arch/powerpc/kvm/book3s_64_slb.S
index f2e6e48..56b983e 100644
--- 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)