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, 12 insertions, 7 deletions

diff --git a/include/hw/ppc/spapr_irq.h b/include/hw/ppc/spapr_irq.h
index 5db3051..a8f9a2a 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;