iommu/vt-d: Disable DMAR for Intel Q35 IGFX

commit 2cda2e10dc8343ae01eae9e999a876b7e7d37861 upstream.

Intel Q35 integrated graphics (8086:29b2) exhibits broken DMAR
behaviour similar to other G4x/GM45 devices for which DMAR is
already disabled via quirks.

When DMAR is enabled, the system may hard lock up during boot or
early device initialization, requiring a reset.

Add the missing PCI ID to the existing quirk list to disable
DMAR for this device.

Fixes: 1f76249 ("iommu/vt-d: Declare Broadwell igfx dmar support snafu")
Cc: stable@vger.kernel.org
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=201185
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=216064
Signed-off-by: Naval Alcalá <ari@naval.cat>
Link: https://lore.kernel.org/r/20260410161622.13549-1-ari@naval.cat
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: aeri

drivers/iommu/intel/iommu.c

@@ -4517,6 +4517,9 @@ static void quirk_iommu_igfx(struct pci_dev *dev)
 	disable_igfx_iommu = 1;
 }
 
+/* Q35 integrated gfx dmar support is totally busted. */
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x29b2, quirk_iommu_igfx);
+
 /* G4x/GM45 integrated gfx dmar support is totally busted. */
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2a40, quirk_iommu_igfx);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e00, quirk_iommu_igfx);