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

Q35 has now ACPI hotplug enabled by default for PCI(e) devices.
As opposed to native PCIe hotplug, guests like Fedora 34
will not assign IO range to pcie-root-ports not supporting
native hotplug, resulting into a regression.

Reproduce by:
    qemu-bin -M q35 -device pcie-root-port,id=p1 -monitor stdio
    device_add e1000,bus=p1
In the Guest OS the respective pcie-root-port will have the IO range
disabled.

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

Acked-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
Message-Id: <20210802090057.1709775-1-marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/pci-bridge/gen_pcie_root_port.c b/hw/pci-bridge/gen_pcie_root_port.c
index ec9907917ebc2991dda48169c14eac7e4ba6942b..20099a8ae31afa3ecf7a4740dfe9d094a448e232 100644 (file)
--- 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);