[Intel-gfx] [PATCH v2] vfio/pci: Refine Intel IGD OpRegion support

[Fred Gao]

Bypass the IGD initialization for Intel's dgfx devices with own expansion
ROM and the host/LPC bridge config space are no longer accessed.

v2: simply test if discrete or integrated gfx device
    with root bus. (Alex Williamson)

Cc: Zhenyu Wang <zhenyuw at linux.intel.com>
Cc: Xiong Zhang <xiong.y.zhang at intel.com>
Cc: Hang Yuan <hang.yuan at linux.intel.com>
Cc: Stuart Summers <stuart.summers at intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
Signed-off-by: Fred Gao <fred.gao at intel.com>
---
 drivers/vfio/pci/vfio_pci.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index f634c81998bb..9258ccfadb79 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -336,10 +336,11 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
 	if (!vfio_vga_disabled() && vfio_pci_is_vga(pdev))
 		vdev->has_vga = true;
 
-
+	/* Intel's dgfx should not appear on root bus */
 	if (vfio_pci_is_vga(pdev) &&
 	    pdev->vendor == PCI_VENDOR_ID_INTEL &&
-	    IS_ENABLED(CONFIG_VFIO_PCI_IGD)) {
+	    IS_ENABLED(CONFIG_VFIO_PCI_IGD) &&
+	    pci_is_root_bus(pdev->bus)) {
 		ret = vfio_pci_igd_init(vdev);
 		if (ret) {
 			pci_warn(pdev, "Failed to setup Intel IGD regions\n");
-- 
2.24.1.1.gb6d4d82bd5