kvm: remove hard dependency on pci

The msi routing code in kvm calls some pci functions: provide
some stubs to enable builds without pci.

Also, to make this more obvious, guard them via a pci_available boolean
(which also can be reused in other places).

Fixes: e1d4fb2de ("kvm-irqchip: x86: add msi route notify fn")
Fixes: 767a554a0 ("kvm-all: Pass requester ID to MSI routing functions")
Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

hw/pci/pci-stub.c

@@ -27,6 +27,7 @@
 #include "hw/pci/msi.h"
 
 bool msi_nonbroken;
+bool pci_available;
 
 PciInfoList *qmp_query_pci(Error **errp)
 {
@@ -38,3 +39,16 @@ void hmp_pcie_aer_inject_error(Monitor *mon, const QDict *qdict)
 {
     monitor_printf(mon, "PCI devices not supported\n");
 }
+
+/* kvm-all wants this */
+MSIMessage pci_get_msi_message(PCIDevice *dev, int vector)
+{
+    g_assert(false);
+    return (MSIMessage){};
+}
+
+uint16_t pci_requester_id(PCIDevice *dev)
+{
+    g_assert(false);
+    return 0;
+}

hw/pci/pci.c

@@ -49,6 +49,8 @@
 # define PCI_DPRINTF(format, ...)       do { } while (0)
 #endif
 
+bool pci_available = true;
+
 static void pcibus_dev_print(Monitor *mon, DeviceState *dev, int indent);
 static char *pcibus_get_dev_path(DeviceState *dev);
 static char *pcibus_get_fw_dev_path(DeviceState *dev);