KVM: PPC: Use get/set for to_svcpu to help preemption

When running the 64-bit Book3s PR code without CONFIG_PREEMPT_NONE, we were
doing a few things wrong, most notably access to PACA fields without making
sure that the pointers stay stable accross the access (preempt_disable()).

This patch moves to_svcpu towards a get/put model which allows us to disable
preemption while accessing the shadow vcpu fields in the PACA. That way we
can run preemptible and everyone's happy!

Reported-by: Jörg Sommer <joerg@alea.gnuu.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/powerpc/kvm/trace.h b/arch/powerpc/kvm/trace.h
index b135d3d397db..609d8bfb54e3 100644
--- a/arch/powerpc/kvm/trace.h
+++ b/arch/powerpc/kvm/trace.h
@@ -118,11 +118,14 @@ TRACE_EVENT(kvm_book3s_exit,
         ),
 
         TP_fast_assign(
+                struct kvmppc_book3s_shadow_vcpu *svcpu;
                 __entry->exit_nr        = exit_nr;
                 __entry->pc             = kvmppc_get_pc(vcpu);
                 __entry->dar            = kvmppc_get_fault_dar(vcpu);
                 __entry->msr            = vcpu->arch.shared->msr;
-                __entry->srr1           = to_svcpu(vcpu)->shadow_srr1;
+                svcpu = svcpu_get(vcpu);
+                __entry->srr1           = svcpu->shadow_srr1;
+                svcpu_put(svcpu);
         ),
 
         TP_printk("exit=0x%x | pc=0x%lx | msr=0x%lx | dar=0x%lx | srr1=0x%lx",