ppc/vhyp: reset exception state when handling vhyp hcall

Convention is to reset the exception_index and error_code after handling
an interrupt. The vhyp hcall handler fails to do this. This does not
appear to have ill effects because cpu_handle_exception() clears
exception_index later, but it is fragile and inconsistent. Reset the
exception state after handling vhyp hcall like other handlers.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

target/ppc/excp_helper.c

@@ -843,6 +843,7 @@ static void powerpc_excp_7xx(PowerPCCPU *cpu, int excp)
             PPCVirtualHypervisorClass *vhc =
                 PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp);
             vhc->hypercall(cpu->vhyp, cpu);
+            powerpc_reset_excp_state(cpu);
             return;
         }
 
@@ -1014,6 +1015,7 @@ static void powerpc_excp_74xx(PowerPCCPU *cpu, int excp)
             PPCVirtualHypervisorClass *vhc =
                 PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp);
             vhc->hypercall(cpu->vhyp, cpu);
+            powerpc_reset_excp_state(cpu);
             return;
         }
 
@@ -1526,6 +1528,7 @@ static void powerpc_excp_books(PowerPCCPU *cpu, int excp)
             PPCVirtualHypervisorClass *vhc =
                 PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp);
             vhc->hypercall(cpu->vhyp, cpu);
+            powerpc_reset_excp_state(cpu);
             return;
         }
         if (env->insns_flags2 & PPC2_ISA310) {