KVM: PPC: booke: add GS documentation for program interrupt

The comment for program interrupts triggered when using bookehv was
misleading. Update it to mention why MSR_GS indicates that we have
to inject an interrupt into the guest again, not emulate it.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index af02d9dbd951..7df3f3ae71d9 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -685,8 +685,14 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 
         case BOOKE_INTERRUPT_PROGRAM:
                 if (vcpu->arch.shared->msr & (MSR_PR | MSR_GS)) {
-                        /* Program traps generated by user-level software must be handled
-                         * by the guest kernel. */
+                        /*
+                         * Program traps generated by user-level software must
+                         * be handled by the guest kernel.
+                         *
+                         * In GS mode, hypervisor privileged instructions trap
+                         * on BOOKE_INTERRUPT_HV_PRIV, not here, so these are
+                         * actual program interrupts, handled by the guest.
+                         */
                         kvmppc_core_queue_program(vcpu, vcpu->arch.fault_esr);
                         r = RESUME_GUEST;
                         kvmppc_account_exit(vcpu, USR_PR_INST);