Introduce x-pci-class-code option to allow users to override PCI class
code of a device, similar to the existing x-pci-vendor-id option. Only
the lower 24 bits of this option are used, though a uint32 is used here
for determining whether the value is valid and set by user.
Additionally, to ensure VGA ranges are only exposed on VGA devices,
pci_register_vga() is now called in vfio_pci_config_setup(), after
the class code override is completed.
This is mainly intended for IGD devices that expose themselves either
as VGA controller (primary display) or Display controller (non-primary
display). The UEFI GOP driver depends on the device reporting a VGA
controller class code (0x030000).
Signed-off-by: Tomita Moeko <tomitamo...@gmail.com>
---
v3:
* Save the vdev class code when it is unspecified.
* Call pci_register_vga() in vfio_pci_config_setup() to ensure VGA
regions are only get exposed when vdev is VGA.
* Check vdev class code in vfio_is_vga().
Link:
https://lore.kernel.org/qemu-devel/20250528155548.29344-1-tomitamo...@gmail.com/
v2:
* Add vdev class code check in vfio_populate_vga().
* Fix type in trace-events.
Link: https://lore.kernel.org/all/20250524153102.19747-1-tomitamo...@gmail.com/
hw/vfio/pci.c | 29 +++++++++++++++++++++++++----
hw/vfio/pci.h | 6 ++----
hw/vfio/trace-events | 1 +
3 files changed, 28 insertions(+), 8 deletions(-)
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 1093b28df7..910042c6c2 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2893,10 +2893,6 @@ bool vfio_populate_vga(VFIOPCIDevice *vdev, Error **errp)
"vfio-vga-io@0x3c0",
QEMU_PCI_VGA_IO_HI_SIZE);
- pci_register_vga(&vdev->pdev, &vdev->vga->region[QEMU_PCI_VGA_MEM].mem,
- &vdev->vga->region[QEMU_PCI_VGA_IO_LO].mem,
- &vdev->vga->region[QEMU_PCI_VGA_IO_HI].mem);
-
return true;
}
@@ -3228,6 +3224,23 @@ bool vfio_pci_config_setup(VFIOPCIDevice *vdev, Error **errp)
vdev->sub_device_id);
}
+ /*
+ * Class code is a 24-bit value at config space 0x09. Allow overriding it
+ * with any 24-bit value.
+ */
+ if (vdev->class_code != PCI_ANY_ID) {
+ if (vdev->class_code > 0xffffff) {
+ error_setg(errp, "invalid PCI class code provided");
+ return false;
+ }
+ /* Higher 24 bits of PCI_CLASS_REVISION are class code */
+ vfio_add_emulated_long(vdev, PCI_CLASS_REVISION,
+ vdev->class_code << 8, ~0xff);
+ trace_vfio_pci_emulated_class_code(vbasedev->name, vdev->class_code);
+ } else {
+ vdev->class_code = pci_get_long(pdev->config + PCI_CLASS_REVISION) >>
8;
+ }
+
/* QEMU can change multi-function devices to single function, or reverse
*/
vdev->emulated_config_bits[PCI_HEADER_TYPE] =
PCI_HEADER_TYPE_MULTI_FUNCTION;
@@ -3257,6 +3270,12 @@ bool vfio_pci_config_setup(VFIOPCIDevice *vdev, Error
**errp)
vfio_bars_register(vdev);
+ if (vdev->vga && vfio_is_vga(vdev)) {
+ pci_register_vga(&vdev->pdev, &vdev->vga->region[QEMU_PCI_VGA_MEM].mem,
+ &vdev->vga->region[QEMU_PCI_VGA_IO_LO].mem,
+ &vdev->vga->region[QEMU_PCI_VGA_IO_HI].mem);
+ }
+
return true;
}
@@ -3643,6 +3662,8 @@ static const Property vfio_pci_dev_properties[] = {
sub_vendor_id, PCI_ANY_ID),
DEFINE_PROP_UINT32("x-pci-sub-device-id", VFIOPCIDevice,
sub_device_id, PCI_ANY_ID),
+ DEFINE_PROP_UINT32("x-pci-class-code", VFIOPCIDevice,
+ class_code, PCI_ANY_ID),
DEFINE_PROP_UINT32("x-igd-gms", VFIOPCIDevice, igd_gms, 0),
DEFINE_PROP_UNSIGNED_NODEFAULT("x-nv-gpudirect-clique", VFIOPCIDevice,
nv_gpudirect_clique,
diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index 495fae737d..4aa6461117 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -157,6 +157,7 @@ struct VFIOPCIDevice {
uint32_t device_id;
uint32_t sub_vendor_id;
uint32_t sub_device_id;
+ uint32_t class_code;
uint32_t features;
#define VFIO_FEATURE_ENABLE_VGA_BIT 0
#define VFIO_FEATURE_ENABLE_VGA (1 << VFIO_FEATURE_ENABLE_VGA_BIT)
@@ -205,10 +206,7 @@ static inline bool vfio_pci_is(VFIOPCIDevice *vdev,
uint32_t vendor, uint32_t de
static inline bool vfio_is_vga(VFIOPCIDevice *vdev)
{
- PCIDevice *pdev = &vdev->pdev;
- uint16_t class = pci_get_word(pdev->config + PCI_CLASS_DEVICE);
-
- return class == PCI_CLASS_DISPLAY_VGA;
+ return (vdev->class_code >> 8) == PCI_CLASS_DISPLAY_VGA;
}
/* MSI/MSI-X/INTx */
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index 8ec0ad0cde..fc6ed230d0 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -48,6 +48,7 @@ vfio_pci_emulated_vendor_id(const char *name, uint16_t val) "%s
0x%04x"
vfio_pci_emulated_device_id(const char *name, uint16_t val) "%s 0x%04x"
vfio_pci_emulated_sub_vendor_id(const char *name, uint16_t val) "%s 0x%04x"
vfio_pci_emulated_sub_device_id(const char *name, uint16_t val) "%s 0x%04x"
+vfio_pci_emulated_class_code(const char *name, uint32_t val) "%s 0x%06x"
# pci-quirks.c
vfio_quirk_rom_in_denylist(const char *name, uint16_t vid, uint16_t did) "%s
%04x:%04x"
