[Qemu-devel] [PATCH] hw/intc: fix failure return for xics_alloc_block()

[Greg Kurz <gkurz@linux.vnet.ibm.com>]

From: Brian W. Hart <hartb@linux.vnet.ibm.com>

xics_alloc_block() does not return a clear error code when it
fails to allocate a block of interrupts. Instead it returns the
base interrupt number minus 1. This change updates it to return a
clear -1 in case of failure (following the example of xics_alloc()).

The two callers of xics_alloc_block() are updated to check for
a negative return as an error. They had previously checked for
a 0 return as an error, which wrongly treated most failures as
successes.

Fixes: bee763dbfb8cfceea112131970da07f215f293a6
Signed-off-by: Brian W. Hart <hartb@linux.vnet.ibm.com>
[only pass src and num to trace_xics_alloc_block_failed_no_left,
 added trace_xics_alloc_block_failed_no_left definition to trace-events]
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
---
 hw/intc/xics.c     |   10 ++++++----
 hw/ppc/spapr_pci.c |    9 +++++----
 trace-events       |    1 +
 3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index cd91ddc4d1d9..3bb77ff96e7b 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -763,11 +763,13 @@ 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) {
+        trace_xics_alloc_block_failed_no_left(src, num);
+        return -1;
+    }
 
-    if (first >= 0) {
-        for (i = first; i < first + num; ++i) {
-            ics_set_irq_type(ics, i, lsi);
-        }
+    for (i = first; i < first + num; ++i) {
+        ics_set_irq_type(ics, i, lsi);
     }
     first += ics->offset;
 
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index cca9257fecc5..ba33cee2a465 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -275,7 +275,8 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     unsigned int req_num = rtas_ld(args, 4); /* 0 == remove all */
     unsigned int seq_num = rtas_ld(args, 5);
     unsigned int ret_intr_type;
-    unsigned int irq, max_irqs = 0, num = 0;
+    unsigned int max_irqs = 0, num = 0;
+    int irq;
     sPAPRPHBState *phb = NULL;
     PCIDevice *pdev = NULL;
     spapr_pci_msi *msi;
@@ -354,7 +355,7 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     /* Allocate MSIs */
     irq = xics_alloc_block(spapr->icp, 0, req_num, false,
                            ret_intr_type == RTAS_TYPE_MSI);
-    if (!irq) {
+    if (irq < 0) {
         error_report("Cannot allocate MSIs for device %x", config_addr);
         rtas_st(rets, 0, RTAS_OUT_HW_ERROR);
         return;
@@ -1359,10 +1360,10 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
 
     /* Initialize the LSI table */
     for (i = 0; i < PCI_NUM_PINS; i++) {
-        uint32_t irq;
+        int32_t irq;
 
         irq = xics_alloc_block(spapr->icp, 0, 1, true, false);
-        if (!irq) {
+        if (irq < 0) {
             error_setg(errp, "spapr_allocate_lsi failed");
             return;
         }
diff --git a/trace-events b/trace-events
index c9ac144ceee4..07b0250aaf11 100644
--- a/trace-events
+++ b/trace-events
@@ -1393,6 +1393,7 @@ xics_alloc(int src, int irq) "source#%d, irq %d"
 xics_alloc_failed_hint(int src, int irq) "source#%d, irq %d is already in use"
 xics_alloc_failed_no_left(int src) "source#%d, no irq left"
 xics_alloc_block(int src, int first, int num, bool lsi, int align) "source#%d, first irq %d, %d irqs, lsi=%d, alignnum %d"
+xics_alloc_block_failed_no_left(int src, int num) "source#%d, cannot find %d consecutive irqs"
 xics_ics_free(int src, int irq, int num) "Source#%d, first irq %d, %d irqs"
 xics_ics_free_warn(int src, int irq) "Source#%d, irq %d is already free"