[PATCH] hw/pcie-root-port: Fix hotplug for PCI devices requiring IO

[Marcel Apfelbaum]

Q35 has now ACPI hotplug enabled by default for PCI(e) devices.
As opposed to native PCIe hotplug, some guests will not assign
IO range to pcie-root-ports not supporting native hotplug,
resulting into a regression.

Fix it by setting the "reserve-io" hint capability of the
pcie-root-ports so the firmware will allocate the IO range instead.

Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
---
 hw/pci-bridge/gen_pcie_root_port.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/pci-bridge/gen_pcie_root_port.c 
b/hw/pci-bridge/gen_pcie_root_port.c
index ec9907917e..20099a8ae3 100644
--- a/hw/pci-bridge/gen_pcie_root_port.c
+++ b/hw/pci-bridge/gen_pcie_root_port.c
@@ -28,6 +28,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(GenPCIERootPort, 
GEN_PCIE_ROOT_PORT)
         (GEN_PCIE_ROOT_PORT_AER_OFFSET + PCI_ERR_SIZEOF)
 
 #define GEN_PCIE_ROOT_PORT_MSIX_NR_VECTOR       1
+#define GEN_PCIE_ROOT_DEFAULT_IO_RANGE          4096
 
 struct GenPCIERootPort {
     /*< private >*/
@@ -75,6 +76,7 @@ static bool gen_rp_test_migrate_msix(void *opaque, int 
version_id)
 static void gen_rp_realize(DeviceState *dev, Error **errp)
 {
     PCIDevice *d = PCI_DEVICE(dev);
+    PCIESlot *s = PCIE_SLOT(d);
     GenPCIERootPort *grp = GEN_PCIE_ROOT_PORT(d);
     PCIERootPortClass *rpc = PCIE_ROOT_PORT_GET_CLASS(d);
     Error *local_err = NULL;
@@ -85,6 +87,9 @@ static void gen_rp_realize(DeviceState *dev, Error **errp)
         return;
     }
 
+    if (grp->res_reserve.io == -1 && s->hotplug && !s->native_hotplug) {
+        grp->res_reserve.io = GEN_PCIE_ROOT_DEFAULT_IO_RANGE;
+    }
     int rc = pci_bridge_qemu_reserve_cap_init(d, 0,
                                               grp->res_reserve, errp);
 
-- 
2.31.1