spapr: introduce an 'ic-mode' machine option

This option is used to select the interrupt controller mode (XICS or
XIVE) with which the machine will operate. XICS being the default
mode for now.

When running a machine with the XIVE interrupt mode backend, the guest
OS is required to have support for the XIVE exploitation mode. In the
case of legacy OS, the mode selected by CAS should be XICS and the OS
should fail to boot. However, QEMU could possibly detect it, terminate
the boot process and reset to stop in the SLOF firmware. This is not
yet handled.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 43 insertions, 7 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 2f87c8ba19..65c6065602 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1104,10 +1104,9 @@ static void spapr_dt_ov5_platform_support(sPAPRMachineState *spapr, void *fdt,
                                           int chosen)
 {
     PowerPCCPU *first_ppc_cpu = POWERPC_CPU(first_cpu);
-    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
 
     char val[2 * 4] = {
-        23, smc->irq->ov5, /* Xive mode. */
+        23, spapr->irq->ov5, /* Xive mode. */
         24, 0x00, /* Hash/Radix, filled in below. */
         25, 0x00, /* Hash options: Segment Tables == no, GTSE == no. */
         26, 0x40, /* Radix options: GTSE == yes. */
@@ -1276,7 +1275,7 @@ static void *spapr_build_fdt(sPAPRMachineState *spapr,
     _FDT(fdt_setprop_cell(fdt, 0, "#size-cells", 2));
 
     /* /interrupt controller */
-    smc->irq->dt_populate(spapr, spapr_max_server_number(spapr), fdt,
+    spapr->irq->dt_populate(spapr, spapr_max_server_number(spapr), fdt,
                           PHANDLE_XICP);
 
     ret = spapr_populate_memory(spapr, fdt);
@@ -1297,7 +1296,8 @@ static void *spapr_build_fdt(sPAPRMachineState *spapr,
     }
 
     QLIST_FOREACH(phb, &spapr->phbs, list) {
-        ret = spapr_populate_pci_dt(phb, PHANDLE_XICP, fdt, smc->irq->nr_msis);
+        ret = spapr_populate_pci_dt(phb, PHANDLE_XICP, fdt,
+                                    spapr->irq->nr_msis);
         if (ret < 0) {
             error_report("couldn't setup PCI devices in fdt");
             exit(1);
@@ -2633,7 +2633,7 @@ static void spapr_machine_init(MachineState *machine)
     spapr_ovec_set(spapr->ov5, OV5_DRMEM_V2);
 
     /* advertise XIVE on POWER9 machines */
-    if (smc->irq->ov5 & SPAPR_OV5_XIVE_EXPLOIT) {
+    if (spapr->irq->ov5 & SPAPR_OV5_XIVE_EXPLOIT) {
         if (ppc_type_check_compat(machine->cpu_type, CPU_POWERPC_LOGICAL_3_00,
                                   0, spapr->max_compat_pvr)) {
             spapr_ovec_set(spapr->ov5, OV5_XIVE_EXPLOIT);
@@ -3053,9 +3053,38 @@ static void spapr_set_vsmt(Object *obj, Visitor *v, const char *name,
     visit_type_uint32(v, name, (uint32_t *)opaque, errp);
 }
 
+static char *spapr_get_ic_mode(Object *obj, Error **errp)
+{
+    sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
+
+    if (spapr->irq == &spapr_irq_xics_legacy) {
+        return g_strdup("legacy");
+    } else if (spapr->irq == &spapr_irq_xics) {
+        return g_strdup("xics");
+    } else if (spapr->irq == &spapr_irq_xive) {
+        return g_strdup("xive");
+    }
+    g_assert_not_reached();
+}
+
+static void spapr_set_ic_mode(Object *obj, const char *value, Error **errp)
+{
+    sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
+
+    /* The legacy IRQ backend can not be set */
+    if (strcmp(value, "xics") == 0) {
+        spapr->irq = &spapr_irq_xics;
+    } else if (strcmp(value, "xive") == 0) {
+        spapr->irq = &spapr_irq_xive;
+    } else {
+        error_setg(errp, "Bad value for \"ic-mode\" property");
+    }
+}
+
 static void spapr_instance_init(Object *obj)
 {
     sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
+    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
 
     spapr->htab_fd = -1;
     spapr->use_hotplug_event_source = true;
@@ -3089,6 +3118,14 @@ static void spapr_instance_init(Object *obj)
                                     " the host's SMT mode", &error_abort);
     object_property_add_bool(obj, "vfio-no-msix-emulation",
                              spapr_get_msix_emulation, NULL, NULL);
+
+    /* The machine class defines the default interrupt controller mode */
+    spapr->irq = smc->irq;
+    object_property_add_str(obj, "ic-mode", spapr_get_ic_mode,
+                            spapr_set_ic_mode, NULL);
+    object_property_set_description(obj, "ic-mode",
+                 "Specifies the interrupt controller mode (xics, xive)",
+                 NULL);
 }
 
 static void spapr_machine_finalizefn(Object *obj)
@@ -3811,9 +3848,8 @@ static void spapr_pic_print_info(InterruptStatsProvider *obj,
                                  Monitor *mon)
 {
     sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
-    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
 
-    smc->irq->print_info(spapr, mon);
+    spapr->irq->print_info(spapr, mon);
 }
 
 int spapr_get_vcpu_id(PowerPCCPU *cpu)