xics: report errors with the QEMU Error API

Using the return value to report errors is error prone:
- xics_alloc() returns -1 on error but spapr_vio_busdev_realize() errors
  on 0
- xics_alloc_block() returns the unclear value of ics->offset - 1 on error
  but both rtas_ibm_change_msi() and spapr_phb_realize() error on 0

This patch adds an errp argument to xics_alloc() and xics_alloc_block() to
report errors. The return value of these functions is a valid IRQ number
if errp is NULL. It is undefined otherwise.

The corresponding error traces get promotted to error messages. Note that
the "can't allocate IRQ" error message in spapr_vio_busdev_realize() also
moves to xics_alloc(). Similar error message consolidation isn't really
applicable to xics_alloc_block() because callers have extra context (device
config address, MSI or MSIX).

This fixes the issues mentioned above.

Based on previous work from Brian W. Hart.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 9 insertions, 4 deletions

diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index e66ae32881..213a370925 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -712,7 +712,7 @@ static int ics_find_free_block(ICSState *ics, int num, int alignnum)
     return -1;
 }
 
-int xics_alloc(XICSState *icp, int src, int irq_hint, bool lsi)
+int xics_alloc(XICSState *icp, int src, int irq_hint, bool lsi, Error **errp)
 {
     ICSState *ics = &icp->ics[src];
     int irq;
@@ -720,14 +720,14 @@ int xics_alloc(XICSState *icp, int src, int irq_hint, bool lsi)
     if (irq_hint) {
         assert(src == xics_find_source(icp, irq_hint));
         if (!ICS_IRQ_FREE(ics, irq_hint - ics->offset)) {
-            trace_xics_alloc_failed_hint(src, irq_hint);
+            error_setg(errp, "can't allocate IRQ %d: already in use", irq_hint);
             return -1;
         }
         irq = irq_hint;
     } else {
         irq = ics_find_free_block(ics, 1, 1);
         if (irq < 0) {
-            trace_xics_alloc_failed_no_left(src);
+            error_setg(errp, "can't allocate IRQ: no IRQ left");
             return -1;
         }
         irq += ics->offset;
@@ -743,7 +743,8 @@ int xics_alloc(XICSState *icp, int src, int irq_hint, bool lsi)
  * Allocate block of consecutive IRQs, and return the number of the first IRQ in the block.
  * If align==true, aligns the first IRQ number to num.
  */
-int xics_alloc_block(XICSState *icp, int src, int num, bool lsi, bool align)
+int xics_alloc_block(XICSState *icp, int src, int num, bool lsi, bool align,
+                     Error **errp)
 {
     int i, first = -1;
     ICSState *ics = &icp->ics[src];
@@ -763,6 +764,10 @@ int xics_alloc_block(XICSState *icp, int src, int num, bool lsi, bool align)
     } 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;
+    }
 
     if (first >= 0) {
         for (i = first; i < first + num; ++i) {