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| author | Tomita Moeko <tomitamoeko@gmail.com> | 2025-07-24 00:09:05 +0800 |
|---|---|---|
| committer | Cédric Le Goater <clg@redhat.com> | 2025-07-28 17:52:34 +0200 |
| commit | e0b33efe2acc3c6c651bb761394ef597e763e349 (patch) | |
| tree | 0ef26c26d27baabb2ace6de1fdfb82b744be636a | |
| parent | 9751377c3a9445f597c5d0bf134a79c8cb58e45d (diff) | |
| download | qemu-e0b33efe2acc3c6c651bb761394ef597e763e349.zip qemu-e0b33efe2acc3c6c651bb761394ef597e763e349.tar.gz qemu-e0b33efe2acc3c6c651bb761394ef597e763e349.tar.bz2 | |
vfio/igd: Require host VGA decode for legacy mode
Commit a59d06305fff ("vfio/pci: Introduce x-pci-class-code option")
allows user to expose non-VGA IGD device as VGA controller to the
guest. However, legacy mode requires host VGA range access. Check
that GGC.IVD == 0 before enabling legacy mode to ensure IGD is a real
VGA device claiming host VGA ranges.
Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250723160906.44941-2-tomitamoeko@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
| -rw-r--r-- | docs/igd-assign.txt | 1 | ||||
| -rw-r--r-- | hw/vfio/igd.c | 11 |
2 files changed, 7 insertions, 5 deletions
diff --git a/docs/igd-assign.txt b/docs/igd-assign.txt index af4e839..e540403 100644 --- a/docs/igd-assign.txt +++ b/docs/igd-assign.txt @@ -48,6 +48,7 @@ Intel document [1] shows how to dump VBIOS to file. For UEFI Option ROM, see QEMU also provides a "Legacy" mode that implicitly enables full functionality on IGD, it is automatically enabled when * IGD generation is 6 to 9 (Sandy Bridge to Comet Lake) +* IGD claims VGA cycles on host (IGD is VGA controller on host) * Machine type is i440fx * IGD is assigned to guest BDF 00:02.0 * ROM BAR or romfile is present diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c index e7a9d1f..5b1ad1a 100644 --- a/hw/vfio/igd.c +++ b/hw/vfio/igd.c @@ -113,6 +113,7 @@ static int igd_gen(VFIOPCIDevice *vdev) #define IGD_BDSM 0x5c /* Base Data of Stolen Memory */ #define IGD_BDSM_GEN11 0xc0 /* Base Data of Stolen Memory of gen 11 and later */ +#define IGD_GMCH_VGA_DISABLE BIT(1) #define IGD_GMCH_GEN6_GMS_SHIFT 3 /* SNB_GMCH in i915 */ #define IGD_GMCH_GEN6_GMS_MASK 0x1f #define IGD_GMCH_GEN8_GMS_SHIFT 8 /* BDW_GMCH in i915 */ @@ -533,12 +534,14 @@ static bool vfio_pci_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp) /* * For backward compatibility, enable legacy mode when * - Device geneation is 6 to 9 (including both) + * - IGD claims VGA cycles on host * - Machine type is i440fx (pc_piix) * - IGD device is at guest BDF 00:02.0 * - Not manually disabled by x-igd-legacy-mode=off */ if ((vdev->igd_legacy_mode != ON_OFF_AUTO_OFF) && (gen >= 6 && gen <= 9) && + !(gmch & IGD_GMCH_VGA_DISABLE) && !strcmp(MACHINE_GET_CLASS(qdev_get_machine())->family, "pc_piix") && (&vdev->pdev == pci_find_device(pci_device_root_bus(&vdev->pdev), 0, PCI_DEVFN(0x2, 0)))) { @@ -568,12 +571,10 @@ static bool vfio_pci_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp) } /* - * If IGD VGA Disable is clear (expected) and VGA is not already - * enabled, try to enable it. Probably shouldn't be using legacy mode - * without VGA, but also no point in us enabling VGA if disabled in - * hardware. + * If VGA is not already enabled, try to enable it. We shouldn't be + * using legacy mode without VGA. */ - if (!(gmch & 0x2) && !vdev->vga && !vfio_populate_vga(vdev, &err)) { + if (!vdev->vga && !vfio_populate_vga(vdev, &err)) { error_setg(&err, "Unable to enable VGA access"); goto error; } |