[Qemu-devel] [v5][PATCH 2/5] xen, gfx passthrough: create pseudo intel isa bridge

[Tiejun Chen <tiejun.chen@intel.com>]

ISA bridge is needed since Intel gfx drive will probe with Dev31:Fun0
to make graphics device passthrough work well for VMM, that only need
to expose this pseudo ISA bridge to let driver know the real hardware
underneath.

The original patch is from Allen Kay <allen.m.kay@intel.com>

Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
Cc: Allen Kay <allen.m.kay@intel.com>
---
v5:

* Don't set this ISA class property, instead, just fake this ISA bridge
  with 00:1f.0. 

v4:

* Remove some unnecessary "return" in void foo().

v3:

* Fix some typos.
* Improve some return paths.

v2:

* Nothing is changed.

 hw/xen/xen_pt_graphics.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
index 461e526..974b7e9 100644
--- a/hw/xen/xen_pt_graphics.c
+++ b/hw/xen/xen_pt_graphics.c
@@ -230,3 +230,64 @@ out:
     g_free(bios);
     return rc;
 }
+
+static uint32_t isa_bridge_read_config(PCIDevice *d, uint32_t addr, int len)
+{
+    return pci_default_read_config(d, addr, len);
+}
+
+static void isa_bridge_write_config(PCIDevice *d, uint32_t addr, uint32_t v,
+                                    int len)
+{
+    pci_default_write_config(d, addr, v, len);
+}
+
+static void isa_bridge_class_init(ObjectClass *klass, void *data)
+{
+    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
+
+    k->config_read = isa_bridge_read_config;
+    k->config_write = isa_bridge_write_config;
+};
+
+typedef struct {
+    PCIDevice dev;
+} ISABridgeState;
+
+static TypeInfo isa_bridge_info = {
+    .name          = "pseudo-intel-pch-isa-bridge",
+    .parent        = TYPE_PCI_DEVICE,
+    .instance_size = sizeof(ISABridgeState),
+    .class_init = isa_bridge_class_init,
+};
+
+static void xen_pt_graphics_register_types(void)
+{
+    type_register_static(&isa_bridge_info);
+}
+
+type_init(xen_pt_graphics_register_types)
+
+static int create_pseudo_pch_isa_bridge(PCIBus *bus, XenHostPCIDevice *hdev)
+{
+    struct PCIDevice *dev;
+
+    char rid;
+
+    /* We havt to use a simple PCI device to fake this ISA bridge
+     * to avoid making some confusion to BIOS and ACPI.
+     */
+    dev = pci_create(bus, PCI_DEVFN(0x1f, 0), "pseudo-intel-pch-isa-bridge");
+
+    qdev_init_nofail(&dev->qdev);
+
+    pci_config_set_vendor_id(dev->config, hdev->vendor_id);
+    pci_config_set_device_id(dev->config, hdev->device_id);
+
+    xen_host_pci_get_block(hdev, PCI_REVISION_ID, (uint8_t *)&rid, 1);
+
+    pci_config_set_revision(dev->config, rid);
+
+    XEN_PT_LOG(dev, "The pseudo Intel PCH ISA bridge created.\n");
+    return 0;
+}
-- 
1.9.1