spapr: split the IRQ allocation sequence

Today, when a device requests for IRQ number in a sPAPR machine, the
spapr_irq_alloc() routine first scans the ICSState status array to
find an empty slot and then performs the assignement of the selected
numbers. Split this sequence in two distinct routines : spapr_irq_find()
for lookups and spapr_irq_claim() for claiming the IRQ numbers.

This will ease the introduction of a static layout of IRQ numbers.

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

hw/ppc/spapr.c

@@ -3816,6 +3816,36 @@ static int ics_find_free_block(ICSState *ics, int num, int alignnum)
     return -1;
 }
 
+int spapr_irq_find(sPAPRMachineState *spapr, int num, bool align, Error **errp)
+{
+    ICSState *ics = spapr->ics;
+    int first = -1;
+
+    assert(ics);
+
+    /*
+     * MSIMesage::data is used for storing VIRQ so
+     * it has to be aligned to num to support multiple
+     * MSI vectors. MSI-X is not affected by this.
+     * The hint is used for the first IRQ, the rest should
+     * be allocated continuously.
+     */
+    if (align) {
+        assert((num == 1) || (num == 2) || (num == 4) ||
+               (num == 8) || (num == 16) || (num == 32));
+        first = ics_find_free_block(ics, num, num);
+    } else {
+        first = ics_find_free_block(ics, num, 1);
+    }
+
+    if (first < 0) {
+        error_setg(errp, "can't find a free %d-IRQ block", num);
+        return -1;
+    }
+
+    return first + ics->offset;
+}
+
 /*
  * Allocate the IRQ number and set the IRQ type, LSI or MSI
  */
@@ -3894,6 +3924,26 @@ int spapr_irq_alloc_block(sPAPRMachineState *spapr, int num, bool lsi,
     return first;
 }
 
+int spapr_irq_claim(sPAPRMachineState *spapr, int irq, bool lsi, Error **errp)
+{
+    ICSState *ics = spapr->ics;
+
+    assert(ics);
+
+    if (!ics_valid_irq(ics, irq)) {
+        error_setg(errp, "IRQ %d is invalid", irq);
+        return -1;
+    }
+
+    if (!ICS_IRQ_FREE(ics, irq - ics->offset)) {
+        error_setg(errp, "IRQ %d is not free", irq);
+        return -1;
+    }
+
+    spapr_irq_set_lsi(spapr, irq, lsi);
+    return 0;
+}
+
 void spapr_irq_free(sPAPRMachineState *spapr, int irq, int num)
 {
     ICSState *ics = spapr->ics;

hw/ppc/spapr_events.c

@@ -707,13 +707,18 @@ void spapr_clear_pending_events(sPAPRMachineState *spapr)
 
 void spapr_events_init(sPAPRMachineState *spapr)
 {
+    int epow_irq;
+
+    epow_irq = spapr_irq_findone(spapr, &error_fatal);
+
+    spapr_irq_claim(spapr, epow_irq, false, &error_fatal);
+
     QTAILQ_INIT(&spapr->pending_events);
 
     spapr->event_sources = spapr_event_sources_new();
 
     spapr_event_sources_register(spapr->event_sources, EVENT_CLASS_EPOW,
-                                 spapr_irq_alloc(spapr, 0, false,
-                                                  &error_fatal));
+                                 epow_irq);
 
     /* NOTE: if machine supports modern/dedicated hotplug event source,
      * we add it to the device-tree unconditionally. This means we may
@@ -724,9 +729,14 @@ void spapr_events_init(sPAPRMachineState *spapr)
      * checking that it's enabled.
      */
     if (spapr->use_hotplug_event_source) {
+        int hp_irq;
+
+        hp_irq = spapr_irq_findone(spapr, &error_fatal);
+
+        spapr_irq_claim(spapr, hp_irq, false, &error_fatal);
+
         spapr_event_sources_register(spapr->event_sources, EVENT_CLASS_HOT_PLUG,
-                                     spapr_irq_alloc(spapr, 0, false,
-                                                      &error_fatal));
+                                     hp_irq);
     }
 
     spapr->epow_notifier.notify = spapr_powerdown_req;

hw/ppc/spapr_pci.c

@@ -279,6 +279,7 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     spapr_pci_msi *msi;
     int *config_addr_key;
     Error *err = NULL;
+    int i;
 
     /* Fins sPAPRPHBState */
     phb = spapr_pci_find_phb(spapr, buid);
@@ -371,8 +372,7 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     }
 
     /* Allocate MSIs */
-    irq = spapr_irq_alloc_block(spapr, req_num, false,
-                           ret_intr_type == RTAS_TYPE_MSI, &err);
+    irq = spapr_irq_find(spapr, req_num, ret_intr_type == RTAS_TYPE_MSI, &err);
     if (err) {
         error_reportf_err(err, "Can't allocate MSIs for device %x: ",
                           config_addr);
@@ -380,6 +380,16 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, sPAPRMachineState *spapr,
         return;
     }
 
+    for (i = 0; i < req_num; i++) {
+        spapr_irq_claim(spapr, irq + i, false, &err);
+        if (err) {
+            error_reportf_err(err, "Can't allocate MSIs for device %x: ",
+                              config_addr);
+            rtas_st(rets, 0, RTAS_OUT_HW_ERROR);
+            return;
+        }
+    }
+
     /* Release previous MSIs */
     if (msi) {
         spapr_irq_free(spapr, msi->first_irq, msi->num);
@@ -1698,7 +1708,14 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
         uint32_t irq;
         Error *local_err = NULL;
 
-        irq = spapr_irq_alloc_block(spapr, 1, true, false, &local_err);
+        irq = spapr_irq_findone(spapr, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            error_prepend(errp, "can't allocate LSIs: ");
+            return;
+        }
+
+        spapr_irq_claim(spapr, irq, true, &local_err);
         if (local_err) {
             error_propagate(errp, local_err);
             error_prepend(errp, "can't allocate LSIs: ");

hw/ppc/spapr_vio.c

@@ -475,7 +475,15 @@ static void spapr_vio_busdev_realize(DeviceState *qdev, Error **errp)
         dev->qdev.id = id;
     }
 
-    dev->irq = spapr_irq_alloc(spapr, dev->irq, false, &local_err);
+    if (!dev->irq) {
+        dev->irq = spapr_irq_findone(spapr, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    }
+
+    spapr_irq_claim(spapr, dev->irq, false, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;

include/hw/ppc/spapr.h

@@ -776,6 +776,10 @@ int spapr_irq_alloc(sPAPRMachineState *spapr, int irq_hint, bool lsi,
                     Error **errp);
 int spapr_irq_alloc_block(sPAPRMachineState *spapr, int num, bool lsi,
                           bool align, Error **errp);
+int spapr_irq_find(sPAPRMachineState *spapr, int num, bool align,
+                   Error **errp);
+#define spapr_irq_findone(spapr, errp) spapr_irq_find(spapr, 1, false, errp)
+int spapr_irq_claim(sPAPRMachineState *spapr, int irq, bool lsi, Error **errp);
 void spapr_irq_free(sPAPRMachineState *spapr, int irq, int num);
 qemu_irq spapr_qirq(sPAPRMachineState *spapr, int irq);