[Xen-devel] [RFC][PATCH 2/2] xen:i386:pc_piix: create isa bridge specific to IGD passthrough

[Tiejun Chen <tiejun.chen@xxxxxxxxx>]

Currently IGD drivers always need to access PCH by 1f.0, and
PCH vendor/device id is used to identify the card.

Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
---
 hw/i386/pc_piix.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index b559181..b19c7a9 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -50,7 +50,7 @@
 #include "cpu.h"
 #include "qemu/error-report.h"
 #ifdef CONFIG_XEN
-#  include <xen/hvm/hvm_info_table.h>
+#include <xen/hvm/hvm_info_table.h>
 #endif
 
 #define MAX_IDE_BUS 2
@@ -452,6 +452,31 @@ static void pc_init_isa(MachineState *machine)
 }
 
 #ifdef CONFIG_XEN
+static void xen_igd_passthrough_isa_bridge_create(PCIBus *bus)
+{
+    struct PCIDevice *dev;
+    Error *local_err = NULL;
+    uint16_t device_id = 0xffff;
+
+    /* Currently IGD drivers always need to access PCH by 1f.0. */
+    dev = pci_create_simple(bus, PCI_DEVFN(0x1f, 0),
+                            "xen-igd-passthrough-isa-bridge");
+
+    /* Identify PCH card with its own real vendor/device ids.
+     * Here that vendor id is always PCI_VENDOR_ID_INTEL.
+     */
+    if (dev) {
+        device_id = object_property_get_int(OBJECT(dev), "device-id",
+                                            &local_err);
+        if (!local_err && device_id != 0xffff) {
+            pci_config_set_device_id(dev->config, device_id);
+            return;
+        }
+    }
+
+    fprintf(stderr, "xen set xen-igd-passthrough-isa-bridge failed\n");
+}
+
 static void pc_xen_hvm_init(MachineState *machine)
 {
     PCIBus *bus;
@@ -461,6 +486,7 @@ static void pc_xen_hvm_init(MachineState *machine)
     bus = pci_find_primary_bus();
     if (bus != NULL) {
         pci_create_simple(bus, -1, "xen-platform");
+        xen_igd_passthrough_isa_bridge_create(bus);
     }
 }
 #endif
-- 
1.9.1


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