KVM: PPC: Enable lightweight exits again

The PowerPC C ABI defines that registers r14-r31 need to be preserved across
function calls. Since our exit handler is written in C, we can make use of that
and don't need to reload r14-r31 on every entry/exit cycle.

This technique is also used in the BookE code and is called "lightweight exits"
there. To follow the tradition, it's called the same in Book3S.

So far this optimization was disabled though, as the code didn't do what it was
expected to do, but failed to work.

This patch fixes and enables lightweight exits again.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 1 insertions, 3 deletions

diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 492dcc198dd3..fd2a4d531582 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -539,8 +539,6 @@ int kvmppc_handle_pagefault(struct kvm_run *run, struct kvm_vcpu *vcpu,
                 r = kvmppc_emulate_mmio(run, vcpu);
                 if ( r == RESUME_HOST_NV )
                         r = RESUME_HOST;
-                if ( r == RESUME_GUEST_NV )
-                        r = RESUME_GUEST;
         }
 
         return r;
@@ -645,7 +643,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
                 er = kvmppc_emulate_instruction(run, vcpu);
                 switch (er) {
                 case EMULATE_DONE:
-                        r = RESUME_GUEST;
+                        r = RESUME_GUEST_NV;
                         break;
                 case EMULATE_FAIL:
                         printk(KERN_CRIT "%s: emulation at %lx failed (%08x)\n",