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>

2 files changed, 31 insertions, 41 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,
diff --git a/include/hw/ppc/spapr_irq.h b/include/hw/ppc/spapr_irq.h
index 5db305165c..a8f9a2ab11 100644
--- a/include/hw/ppc/spapr_irq.h
+++ b/include/hw/ppc/spapr_irq.h
@@ -16,13 +16,18 @@
  * IRQ range offsets per device type
  */
 #define SPAPR_IRQ_IPI        0x0
-#define SPAPR_IRQ_EPOW       0x1000  /* XICS_IRQ_BASE offset */
-#define SPAPR_IRQ_HOTPLUG    0x1001
-#define SPAPR_IRQ_VIO        0x1100  /* 256 VIO devices */
-#define SPAPR_IRQ_PCI_LSI    0x1200  /* 32+ PHBs devices */
 
-#define SPAPR_IRQ_MSI        0x1300  /* Offset of the dynamic range covered
-                                      * by the bitmap allocator */
+#define SPAPR_XIRQ_BASE      XICS_IRQ_BASE /* 0x1000 */
+#define SPAPR_IRQ_EPOW       (SPAPR_XIRQ_BASE + 0x0000)
+#define SPAPR_IRQ_HOTPLUG    (SPAPR_XIRQ_BASE + 0x0001)
+#define SPAPR_IRQ_VIO        (SPAPR_XIRQ_BASE + 0x0100)  /* 256 VIO devices */
+#define SPAPR_IRQ_PCI_LSI    (SPAPR_XIRQ_BASE + 0x0200)  /* 32+ PHBs devices */
+
+/* Offset of the dynamic range covered by the bitmap allocator */
+#define SPAPR_IRQ_MSI        (SPAPR_XIRQ_BASE + 0x0300)
+
+#define SPAPR_NR_XIRQS       0x1000
+#define SPAPR_NR_MSIS        (SPAPR_XIRQ_BASE + SPAPR_NR_XIRQS - SPAPR_IRQ_MSI)
 
 typedef struct SpaprMachineState SpaprMachineState;
 
@@ -32,7 +37,7 @@ int spapr_irq_msi_alloc(SpaprMachineState *spapr, uint32_t num, bool align,
 void spapr_irq_msi_free(SpaprMachineState *spapr, int irq, uint32_t num);
 
 typedef struct SpaprIrq {
-    uint32_t    nr_irqs;
+    uint32_t    nr_xirqs;
     uint32_t    nr_msis;
     uint8_t     ov5;