[Xen-devel] [PATCH 2/3] V4 qemu-xen-trad: Correctly expose PCH ISA bridge for IGD passthrough

["G.R." <firemeteor@xxxxxxxxxxxxxxxxxxxxx>]

The i915 driver probes chip version through PCH ISA bridge device / vendor ID.
Previously, the PCH ISA bridge is exposed as PCI-PCI bridge in qemu-xen-trad,
which breaks the assumption of the driver. This change fixes the issue by
correctly exposing the ISA bridge to domU.

Note the PIIX3 ISA bridge is still present on the bus (dropping it seems
break qemu all-together), i915 driver still need to be updated to handle this.

Change since last version:
  1. Introduce helper function to avoid exposing PCI_Bus / PCI_Bridge
definition to public.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>,
               Rui Guo <firemeteor@xxxxxxxxxxxxxxxxxxxxx>
Tested-by: Rui Guo <firemeteor@xxxxxxxxxxxxxxxxxxxxx>
Xen-devel: http://marc.info/?l=xen-devel&m=135548433715750
---
 hw/pci.c         |   10 ++++++++++
 hw/pci.h         |    3 +++
 hw/pt-graphics.c |    9 ++++++---
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/hw/pci.c b/hw/pci.c
index f051de1..c423285 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -938,6 +938,16 @@ PCIBus *pci_bridge_init(PCIBus *bus, int devfn,
uint16_t vid, uint16_t did,
     return s->bus;
 }

+PCIBus *pci_isa_bridge_init(PCIBus *bus, int devfn, uint16_t vid, uint16_t did,
+                            uint8_t rid, pci_map_irq_fn map_irq,
const char *name)
+{
+    PCIBus *s = pci_bridge_init(bus, devfn, vid, did, rid, map_irq, name);
+
+    pci_config_set_class(s->parent_dev->config, PCI_CLASS_BRIDGE_ISA);
+    s->parent_dev->config[PCI_HEADER_TYPE] = 0x80;
+    return s;
+}
+
 int pt_chk_bar_overlap(PCIBus *bus, int devfn, uint32_t addr,
                         uint32_t size, uint8_t type)
 {
diff --git a/hw/pci.h b/hw/pci.h
index edc58b6..cacbdd2 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -271,6 +271,9 @@ void pci_info(void);
 PCIBus *pci_bridge_init(PCIBus *bus, int devfn, uint16_t vid, uint16_t did,
                         uint8_t rid, pci_map_irq_fn map_irq, const char *name);

+PCIBus *pci_isa_bridge_init(PCIBus *bus, int devfn, uint16_t vid, uint16_t did,
+                            uint8_t rid, pci_map_irq_fn map_irq,
const char *name);
+
 #define NR_PCI_FUNC          8
 #define NR_PCI_DEV           32
 #define NR_PCI_DEVFN         (NR_PCI_FUNC * NR_PCI_DEV)
diff --git a/hw/pt-graphics.c b/hw/pt-graphics.c
index c6f8869..7302b25 100644
--- a/hw/pt-graphics.c
+++ b/hw/pt-graphics.c
@@ -3,6 +3,7 @@
  */

 #include "pass-through.h"
+#include "pci.h"
 #include "pci/header.h"
 #include "pci/pci.h"

@@ -40,9 +41,11 @@ void intel_pch_init(PCIBus *bus)
     did = pt_pci_host_read(pci_dev_1f, PCI_DEVICE_ID, 2);
     rid = pt_pci_host_read(pci_dev_1f, PCI_REVISION, 1);

-    if ( vid == PCI_VENDOR_ID_INTEL )
-        pci_bridge_init(bus, PCI_DEVFN(0x1f, 0), vid, did, rid,
-                        pch_map_irq, "intel_bridge_1f");
+    if (vid == PCI_VENDOR_ID_INTEL) {
+        pci_isa_bridge_init(bus, PCI_DEVFN(0x1f, 0), vid, did, rid,
+                            pch_map_irq, "intel_bridge_1f");
+
+    }
 }

 uint32_t igd_read_opregion(struct pt_dev *pci_dev)
--
1.7.10.4

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