[PATCH 16/20] spapr, xics, xive: Better use of assert()s on irq claim/free paths

[David Gibson]

The irq claim and free paths for both XICS and XIVE check for some
validity conditions.  Some of these represent genuine runtime failures,
however others - particularly checking that the basic irq number is in a
sane range - could only fail in the case of bugs in the callin code.
Therefore use assert()s instead of runtime failures for those.

In addition the non backend-specific part of the claim/free paths should
only be used for PAPR external irqs, that is in the range SPAPR_XIRQ_BASE
to the maximum irq number.  Put assert()s for that into the top level
dispatchers as well.

Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
---
 hw/intc/spapr_xive.c |  8 ++------
 hw/ppc/spapr_irq.c   | 18 ++++++++++--------
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
index c1c97192a7..47b5ec0b56 100644
--- a/hw/intc/spapr_xive.c
+++ b/hw/intc/spapr_xive.c
@@ -532,9 +532,7 @@ bool spapr_xive_irq_claim(SpaprXive *xive, uint32_t lisn, 
bool lsi)
 {
     XiveSource *xsrc = &xive->source;
 
-    if (lisn >= xive->nr_irqs) {
-        return false;
-    }
+    assert(lisn < xive->nr_irqs);
 
     /*
      * Set default values when allocating an IRQ number
@@ -559,9 +557,7 @@ bool spapr_xive_irq_claim(SpaprXive *xive, uint32_t lisn, 
bool lsi)
 
 bool spapr_xive_irq_free(SpaprXive *xive, uint32_t lisn)
 {
-    if (lisn >= xive->nr_irqs) {
-        return false;
-    }
+    assert(lisn < xive->nr_irqs);
 
     xive->eat[lisn].w &= cpu_to_be64(~EAS_VALID);
     return true;
diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
index c40357a985..261d66ba17 100644
--- a/hw/ppc/spapr_irq.c
+++ b/hw/ppc/spapr_irq.c
@@ -118,11 +118,7 @@ static int spapr_irq_claim_xics(SpaprMachineState *spapr, 
int irq, bool lsi,
     ICSState *ics = spapr->ics;
 
     assert(ics);
-
-    if (!ics_valid_irq(ics, irq)) {
-        error_setg(errp, "IRQ %d is invalid", irq);
-        return -1;
-    }
+    assert(ics_valid_irq(ics, irq));
 
     if (!ics_irq_free(ics, irq - ics->offset)) {
         error_setg(errp, "IRQ %d is not free", irq);
@@ -138,9 +134,9 @@ static void spapr_irq_free_xics(SpaprMachineState *spapr, 
int irq)
     ICSState *ics = spapr->ics;
     uint32_t srcno = irq - ics->offset;
 
-    if (ics_valid_irq(ics, irq)) {
-        memset(&ics->irqs[srcno], 0, sizeof(ICSIRQState));
-    }
+    assert(ics_valid_irq(ics, irq));
+
+    memset(&ics->irqs[srcno], 0, sizeof(ICSIRQState));
 }
 
 static void spapr_irq_print_info_xics(SpaprMachineState *spapr, Monitor *mon)
@@ -628,6 +624,9 @@ void spapr_irq_init(SpaprMachineState *spapr, Error **errp)
 
 int spapr_irq_claim(SpaprMachineState *spapr, int irq, bool lsi, Error **errp)
 {
+    assert(irq >= SPAPR_XIRQ_BASE);
+    assert(irq < (spapr->irq->nr_xirqs + SPAPR_XIRQ_BASE));
+
     return spapr->irq->claim(spapr, irq, lsi, errp);
 }
 
@@ -635,6 +634,9 @@ void spapr_irq_free(SpaprMachineState *spapr, int irq, int 
num)
 {
     int i;
 
+    assert(irq >= SPAPR_XIRQ_BASE);
+    assert((irq+num) <= (spapr->irq->nr_xirqs + SPAPR_XIRQ_BASE));
+
     for (i = irq; i < (irq + num); i++) {
         spapr->irq->free(spapr, irq);
     }
-- 
2.21.0