linux-kernel - [PATCH v3] vfio/pci: match IGD devices in display controller class

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Message-ID: <20250123163416.7653-1-tomitamoeko@gmail.com>
Date: Fri, 24 Jan 2025 00:34:15 +0800
From: Tomita Moeko <tomitamoeko@...il.com>
To: Alex Williamson <alex.williamson@...hat.com>
Cc: Tomita Moeko <tomitamoeko@...il.com>,
	kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v3] vfio/pci: match IGD devices in display controller class

IGD device can either expose as a VGA controller or display controller
depending on whether it is configured as the primary display device in
BIOS. In both cases, the OpRegion may be present. A new helper function
vfio_pci_is_intel_display() is introduced to check if the device might
be an IGD device.

Signed-off-by: Tomita Moeko <tomitamoeko@...il.com>
---
Changelog:
v3:
* Removed BDF condition as Intel discrete GPUs does not have OpRegion
* Added a helper function to match all possible devices with base class
* Renamed from "vfio/pci: update igd matching conditions"
Link: https://lore.kernel.org/lkml/20241230161054.3674-2-tomitamoeko@gmail.com/

v2:
Fix misuse of pci_get_domain_bus_and_slot(), now only compares bdf
without touching device reference count.
Link: https://lore.kernel.org/all/20241229155140.7434-1-tomitamoeko@gmail.com/

 drivers/vfio/pci/vfio_pci.c      | 4 +---
 drivers/vfio/pci/vfio_pci_igd.c  | 6 ++++++
 drivers/vfio/pci/vfio_pci_priv.h | 6 ++++++
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index e727941f589d..5f169496376a 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -111,9 +111,7 @@ static int vfio_pci_open_device(struct vfio_device *core_vdev)
 	if (ret)
 		return ret;
 
-	if (vfio_pci_is_vga(pdev) &&
-	    pdev->vendor == PCI_VENDOR_ID_INTEL &&
-	    IS_ENABLED(CONFIG_VFIO_PCI_IGD)) {
+	if (vfio_pci_is_intel_display(pdev)) {
 		ret = vfio_pci_igd_init(vdev);
 		if (ret && ret != -ENODEV) {
 			pci_warn(pdev, "Failed to setup Intel IGD regions\n");
diff --git a/drivers/vfio/pci/vfio_pci_igd.c b/drivers/vfio/pci/vfio_pci_igd.c
index dd70e2431bd7..ef490a4545f4 100644
--- a/drivers/vfio/pci/vfio_pci_igd.c
+++ b/drivers/vfio/pci/vfio_pci_igd.c
@@ -435,6 +435,12 @@ static int vfio_pci_igd_cfg_init(struct vfio_pci_core_device *vdev)
 	return 0;
 }
 
+bool vfio_pci_is_intel_display(struct pci_dev *pdev)
+{
+	return (pdev->vendor == PCI_VENDOR_ID_INTEL) &&
+	       ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY);
+}
+
 int vfio_pci_igd_init(struct vfio_pci_core_device *vdev)
 {
 	int ret;
diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_priv.h
index 5e4fa69aee16..a9972eacb293 100644
--- a/drivers/vfio/pci/vfio_pci_priv.h
+++ b/drivers/vfio/pci/vfio_pci_priv.h
@@ -67,8 +67,14 @@ void vfio_pci_memory_unlock_and_restore(struct vfio_pci_core_device *vdev,
 					u16 cmd);
 
 #ifdef CONFIG_VFIO_PCI_IGD
+bool vfio_pci_is_intel_display(struct pci_dev *pdev);
 int vfio_pci_igd_init(struct vfio_pci_core_device *vdev);
 #else
+static inline bool vfio_pci_is_intel_display(struct pci_dev *pdev)
+{
+	return false;
+}
+
 static inline int vfio_pci_igd_init(struct vfio_pci_core_device *vdev)
 {
 	return -ENODEV;
-- 
2.45.2