isa: Clean up error handling around isa_bus_new()

We can have at most one ISA bus.  If you try to create another one,
isa_bus_new() complains to stderr and returns null.

isa_bus_new() is called in two contexts, machine's init() and device's
realize() methods.  Since complaining to stderr is not proper in the
latter context, convert isa_bus_new() to Error.

Machine's init():

* mips_jazz_init(), called from the init() methods of machines
  "magnum" and "pica"

* mips_r4k_init(), the init() method of machine "mips"

* pc_init1() called from the init() methods of non-q35 PC machines

* typhoon_init(), called from clipper_init(), the init() method of
  machine "clipper"

These callers always create the first ISA bus, hence isa_bus_new()
can't fail.  Simply pass &error_abort.

Device's realize():

* i82378_realize(), of PCI device "i82378"

* ich9_lpc_realize(), of PCI device "ICH9-LPC"

* pci_ebus_realize(), of PCI device "ebus"

* piix3_realize(), of PCI device "pci-piix3", abstract parent of
  "PIIX3" and "PIIX3-xen"

* piix4_realize(), of PCI device "PIIX4"

* vt82c686b_realize(), of PCI device "VT82C686B"

Propagate the error.  Note that these devices are typically created
only by machine init() methods with qdev_init_nofail() or similar.  If
we screwed up and created an ISA bus before that call, we now give up
right away.  Before, we'd hobble on, and typically die in
isa_bus_irqs().  Similar if someone finds a way to hot-plug one of
these critters.

Cc: Richard Henderson <rth@twiddle.net>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "Hervé Poussineau" <hpoussin@reactos.org>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Hervé Poussineau <hpoussin@reactos.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <1450370121-5768-11-git-send-email-armbru@redhat.com>

5 files changed, 19 insertions, 7 deletions

diff --git a/hw/isa/i82378.c b/hw/isa/i82378.c
index d4c8306..3793c6f 100644
--- a/hw/isa/i82378.c
+++ b/hw/isa/i82378.c
@@ -75,7 +75,10 @@ static void i82378_realize(PCIDevice *pci, Error **errp)
     pci_config_set_interrupt_pin(pci_conf, 1); /* interrupt pin 0 */
 
     isabus = isa_bus_new(dev, get_system_memory(),
-                         pci_address_space_io(pci));
+                         pci_address_space_io(pci), errp);
+    if (!isabus) {
+        return;
+    }
 
     /* This device has:
        2 82C59 (irq)
diff --git a/hw/isa/isa-bus.c b/hw/isa/isa-bus.c
index 43e0cd8..af6ffd6 100644
--- a/hw/isa/isa-bus.c
+++ b/hw/isa/isa-bus.c
@@ -44,10 +44,10 @@ static const TypeInfo isa_bus_info = {
 };
 
 ISABus *isa_bus_new(DeviceState *dev, MemoryRegion* address_space,
-                    MemoryRegion *address_space_io)
+                    MemoryRegion *address_space_io, Error **errp)
 {
     if (isabus) {
-        fprintf(stderr, "Can't create a second ISA bus\n");
+        error_setg(errp, "Can't create a second ISA bus");
         return NULL;
     }
     if (!dev) {
diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
index 8e58449..ed9907d 100644
--- a/hw/isa/lpc_ich9.c
+++ b/hw/isa/lpc_ich9.c
@@ -607,7 +607,11 @@ static void ich9_lpc_realize(PCIDevice *d, Error **errp)
     ICH9LPCState *lpc = ICH9_LPC_DEVICE(d);
     ISABus *isa_bus;
 
-    isa_bus = isa_bus_new(DEVICE(d), get_system_memory(), get_system_io());
+    isa_bus = isa_bus_new(DEVICE(d), get_system_memory(), get_system_io(),
+                          errp);
+    if (!isa_bus) {
+        return;
+    }
 
     pci_set_long(d->wmask + ICH9_LPC_PMBASE,
                  ICH9_LPC_PMBASE_BASE_ADDRESS_MASK);
diff --git a/hw/isa/piix4.c b/hw/isa/piix4.c
index 2c59e91..644cfd9 100644
--- a/hw/isa/piix4.c
+++ b/hw/isa/piix4.c
@@ -90,8 +90,10 @@ static void piix4_realize(PCIDevice *dev, Error **errp)
 {
     PIIX4State *d = PIIX4_PCI_DEVICE(dev);
 
-    isa_bus_new(DEVICE(d), pci_address_space(dev),
-                pci_address_space_io(dev));
+    if (!isa_bus_new(DEVICE(d), pci_address_space(dev),
+                     pci_address_space_io(dev), errp)) {
+        return;
+    }
     piix4_dev = &d->dev;
     qemu_register_reset(piix4_reset, d);
 }
diff --git a/hw/isa/vt82c686.c b/hw/isa/vt82c686.c
index 252e1d7..6c2190b 100644
--- a/hw/isa/vt82c686.c
+++ b/hw/isa/vt82c686.c
@@ -440,7 +440,10 @@ static void vt82c686b_realize(PCIDevice *d, Error **errp)
     int i;
 
     isa_bus = isa_bus_new(DEVICE(d), get_system_memory(),
-                          pci_address_space_io(d));
+                          pci_address_space_io(d), errp);
+    if (!isa_bus) {
+        return;
+    }
 
     pci_conf = d->config;
     pci_config_set_prog_interface(pci_conf, 0x0);