spapr: Clarify and fix handling of nr_irqs

Both the XICS and XIVE interrupt backends have a "nr-irqs" property, but
it means slightly different things.  For XICS (or, strictly, the ICS) it
indicates the number of "real" external IRQs.  Those start at XICS_IRQ_BASE
(0x1000) and don't include the special IPI vector.  For XIVE, however, it
includes the whole IRQ space, including XIVE's many IPI vectors.

The spapr code currently doesn't handle this sensibly, with the
nr_irqs value in SpaprIrq having different meanings depending on the
backend.  We fix this by renaming nr_irqs to nr_xirqs and making it
always indicate just the number of external irqs, adjusting the value
we pass to XIVE accordingly.  We also move to using common constants
in most of the irq configurations, to make it clearer that the IRQ
space looks the same to the guest (and emulated devices), even if the
backend is different.

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

1 files changed, 19 insertions, 34 deletions

diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
index 8c26fa2d1e..3207b6bd01 100644
--- a/hw/ppc/spapr_irq.c
+++ b/hw/ppc/spapr_irq.c
@@ -92,7 +92,7 @@ static void spapr_irq_init_kvm(SpaprMachineState *spapr,
  * XICS IRQ backend.
  */
 
-static void spapr_irq_init_xics(SpaprMachineState *spapr, int nr_irqs,
+static void spapr_irq_init_xics(SpaprMachineState *spapr, int nr_xirqs,
                                 Error **errp)
 {
     Object *obj;
@@ -102,7 +102,7 @@ static void spapr_irq_init_xics(SpaprMachineState *spapr, int nr_irqs,
     object_property_add_child(OBJECT(spapr), "ics", obj, &error_abort);
     object_property_add_const_link(obj, ICS_PROP_XICS, OBJECT(spapr),
                                    &error_fatal);
-    object_property_set_int(obj, nr_irqs, "nr-irqs",  &error_fatal);
+    object_property_set_int(obj, nr_xirqs, "nr-irqs",  &error_fatal);
     object_property_set_bool(obj, true, "realized", &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
@@ -234,13 +234,9 @@ static void spapr_irq_init_kvm_xics(SpaprMachineState *spapr, Error **errp)
     }
 }
 
-#define SPAPR_IRQ_XICS_NR_IRQS     0x1000
-#define SPAPR_IRQ_XICS_NR_MSIS     \
-    (XICS_IRQ_BASE + SPAPR_IRQ_XICS_NR_IRQS - SPAPR_IRQ_MSI)
-
 SpaprIrq spapr_irq_xics = {
-    .nr_irqs     = SPAPR_IRQ_XICS_NR_IRQS,
-    .nr_msis     = SPAPR_IRQ_XICS_NR_MSIS,
+    .nr_xirqs    = SPAPR_NR_XIRQS,
+    .nr_msis     = SPAPR_NR_MSIS,
     .ov5         = SPAPR_OV5_XIVE_LEGACY,
 
     .init        = spapr_irq_init_xics,
@@ -260,7 +256,7 @@ SpaprIrq spapr_irq_xics = {
 /*
  * XIVE IRQ backend.
  */
-static void spapr_irq_init_xive(SpaprMachineState *spapr, int nr_irqs,
+static void spapr_irq_init_xive(SpaprMachineState *spapr, int nr_xirqs,
                                 Error **errp)
 {
     uint32_t nr_servers = spapr_max_server_number(spapr);
@@ -268,7 +264,7 @@ static void spapr_irq_init_xive(SpaprMachineState *spapr, int nr_irqs,
     int i;
 
     dev = qdev_create(NULL, TYPE_SPAPR_XIVE);
-    qdev_prop_set_uint32(dev, "nr-irqs", nr_irqs);
+    qdev_prop_set_uint32(dev, "nr-irqs", nr_xirqs + SPAPR_XIRQ_BASE);
     /*
      * 8 XIVE END structures per CPU. One for each available priority
      */
@@ -308,7 +304,7 @@ static qemu_irq spapr_qirq_xive(SpaprMachineState *spapr, int irq)
 {
     SpaprXive *xive = spapr->xive;
 
-    if (irq >= xive->nr_irqs) {
+    if ((irq < SPAPR_XIRQ_BASE) || (irq >= xive->nr_irqs)) {
         return NULL;
     }
 
@@ -404,17 +400,9 @@ static void spapr_irq_init_kvm_xive(SpaprMachineState *spapr, Error **errp)
     }
 }
 
-/*
- * XIVE uses the full IRQ number space. Set it to 8K to be compatible
- * with XICS.
- */
-
-#define SPAPR_IRQ_XIVE_NR_IRQS     0x2000
-#define SPAPR_IRQ_XIVE_NR_MSIS     (SPAPR_IRQ_XIVE_NR_IRQS - SPAPR_IRQ_MSI)
-
 SpaprIrq spapr_irq_xive = {
-    .nr_irqs     = SPAPR_IRQ_XIVE_NR_IRQS,
-    .nr_msis     = SPAPR_IRQ_XIVE_NR_MSIS,
+    .nr_xirqs    = SPAPR_NR_XIRQS,
+    .nr_msis     = SPAPR_NR_MSIS,
     .ov5         = SPAPR_OV5_XIVE_EXPLOIT,
 
     .init        = spapr_irq_init_xive,
@@ -450,18 +438,18 @@ static SpaprIrq *spapr_irq_current(SpaprMachineState *spapr)
         &spapr_irq_xive : &spapr_irq_xics;
 }
 
-static void spapr_irq_init_dual(SpaprMachineState *spapr, int nr_irqs,
+static void spapr_irq_init_dual(SpaprMachineState *spapr, int nr_xirqs,
                                 Error **errp)
 {
     Error *local_err = NULL;
 
-    spapr_irq_xics.init(spapr, spapr_irq_xics.nr_irqs, &local_err);
+    spapr_irq_xics.init(spapr, spapr_irq_xics.nr_xirqs, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
     }
 
-    spapr_irq_xive.init(spapr, spapr_irq_xive.nr_irqs, &local_err);
+    spapr_irq_xive.init(spapr, spapr_irq_xive.nr_xirqs, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -586,12 +574,9 @@ static const char *spapr_irq_get_nodename_dual(SpaprMachineState *spapr)
 /*
  * Define values in sync with the XIVE and XICS backend
  */
-#define SPAPR_IRQ_DUAL_NR_IRQS     0x2000
-#define SPAPR_IRQ_DUAL_NR_MSIS     (SPAPR_IRQ_DUAL_NR_IRQS - SPAPR_IRQ_MSI)
-
 SpaprIrq spapr_irq_dual = {
-    .nr_irqs     = SPAPR_IRQ_DUAL_NR_IRQS,
-    .nr_msis     = SPAPR_IRQ_DUAL_NR_MSIS,
+    .nr_xirqs    = SPAPR_NR_XIRQS,
+    .nr_msis     = SPAPR_NR_MSIS,
     .ov5         = SPAPR_OV5_XIVE_BOTH,
 
     .init        = spapr_irq_init_dual,
@@ -693,10 +678,10 @@ void spapr_irq_init(SpaprMachineState *spapr, Error **errp)
         spapr_irq_msi_init(spapr, spapr->irq->nr_msis);
     }
 
-    spapr->irq->init(spapr, spapr->irq->nr_irqs, errp);
+    spapr->irq->init(spapr, spapr->irq->nr_xirqs, errp);
 
     spapr->qirqs = qemu_allocate_irqs(spapr->irq->set_irq, spapr,
-                                      spapr->irq->nr_irqs);
+                                      spapr->irq->nr_xirqs + SPAPR_XIRQ_BASE);
 }
 
 int spapr_irq_claim(SpaprMachineState *spapr, int irq, bool lsi, Error **errp)
@@ -804,11 +789,11 @@ int spapr_irq_find(SpaprMachineState *spapr, int num, bool align, Error **errp)
     return first + ics->offset;
 }
 
-#define SPAPR_IRQ_XICS_LEGACY_NR_IRQS     0x400
+#define SPAPR_IRQ_XICS_LEGACY_NR_XIRQS     0x400
 
 SpaprIrq spapr_irq_xics_legacy = {
-    .nr_irqs     = SPAPR_IRQ_XICS_LEGACY_NR_IRQS,
-    .nr_msis     = SPAPR_IRQ_XICS_LEGACY_NR_IRQS,
+    .nr_xirqs    = SPAPR_IRQ_XICS_LEGACY_NR_XIRQS,
+    .nr_msis     = SPAPR_IRQ_XICS_LEGACY_NR_XIRQS,
     .ov5         = SPAPR_OV5_XIVE_LEGACY,
 
     .init        = spapr_irq_init_xics,