spapr: introduce a spapr_irq class 'nr_msis' attribute

The number of MSI interrupts a sPAPR machine can allocate is in direct
relation with the number of interrupts of the sPAPRIrq backend. Define
statically this value at the sPAPRIrq class level and use it for the
"ibm,pe-total-#msi" property of the sPAPR PHB.

According to the PAPR specs, "ibm,pe-total-#msi" defines the maximum
number of MSIs that are available to the PE. We choose to advertise
the maximum number of MSIs that are available to the machine for
simplicity of the model and to avoid segmenting the MSI interrupt pool
which can be easily shared. If the pool limit is reached, it can be
extended dynamically.

Finally, remove XICS_IRQS_SPAPR which is now unused.

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

hw/ppc/spapr_irq.c

@@ -99,7 +99,7 @@ static void spapr_irq_init_xics(sPAPRMachineState *spapr, Error **errp)
 
     /* Initialize the MSI IRQ allocator. */
     if (!SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
-        spapr_irq_msi_init(spapr, XICS_IRQ_BASE + nr_irqs - SPAPR_IRQ_MSI);
+        spapr_irq_msi_init(spapr, smc->irq->nr_msis);
     }
 
     if (kvm_enabled()) {
@@ -195,8 +195,13 @@ static void spapr_irq_print_info_xics(sPAPRMachineState *spapr, Monitor *mon)
     ics_pic_print_info(spapr->ics, mon);
 }
 
+#define SPAPR_IRQ_XICS_NR_IRQS     0x400
+#define SPAPR_IRQ_XICS_NR_MSIS     \
+    (XICS_IRQ_BASE + SPAPR_IRQ_XICS_NR_IRQS - SPAPR_IRQ_MSI)
+
 sPAPRIrq spapr_irq_xics = {
-    .nr_irqs     = XICS_IRQS_SPAPR,
+    .nr_irqs     = SPAPR_IRQ_XICS_NR_IRQS,
+    .nr_msis     = SPAPR_IRQ_XICS_NR_MSIS,
 
     .init        = spapr_irq_init_xics,
     .claim       = spapr_irq_claim_xics,

hw/ppc/spapr_pci.c

@@ -2121,6 +2121,7 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
     sPAPRTCETable *tcet;
     PCIBus *bus = PCI_HOST_BRIDGE(phb)->bus;
     sPAPRFDT s_fdt;
+    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(qdev_get_machine());
 
     /* Start populating the FDT */
     nodename = g_strdup_printf("pci@%" PRIx64, phb->buid);
@@ -2138,8 +2139,8 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
     _FDT(fdt_setprop(fdt, bus_off, "ranges", &ranges, sizeof_ranges));
     _FDT(fdt_setprop(fdt, bus_off, "reg", &bus_reg, sizeof(bus_reg)));
     _FDT(fdt_setprop_cell(fdt, bus_off, "ibm,pci-config-space-type", 0x1));
-    /* TODO: fine tune the total count of allocatable MSIs per PHB */
-    _FDT(fdt_setprop_cell(fdt, bus_off, "ibm,pe-total-#msi", XICS_IRQS_SPAPR));
+    _FDT(fdt_setprop_cell(fdt, bus_off, "ibm,pe-total-#msi",
+                          smc->irq->nr_msis));
 
     /* Dynamic DMA window */
     if (phb->ddw_enabled) {

include/hw/ppc/spapr_irq.h

@@ -31,6 +31,7 @@ void spapr_irq_msi_reset(sPAPRMachineState *spapr);
 
 typedef struct sPAPRIrq {
     uint32_t    nr_irqs;
+    uint32_t    nr_msis;
 
     void (*init)(sPAPRMachineState *spapr, Error **errp);
     int (*claim)(sPAPRMachineState *spapr, int irq, bool lsi, Error **errp);

include/hw/ppc/xics.h

@@ -181,8 +181,6 @@ typedef struct XICSFabricClass {
     ICPState *(*icp_get)(XICSFabric *xi, int server);
 } XICSFabricClass;
 
-#define XICS_IRQS_SPAPR               1024
-
 void spapr_dt_xics(int nr_servers, void *fdt, uint32_t phandle);
 
 ICPState *xics_icp_get(XICSFabric *xi, int server);