* [PATCH] iommu/vt-d: Disable DMAR for Intel Q35 IGFX
@ 2026-04-10 16:16 Naval Alcalá
2026-05-08 7:57 ` Baolu Lu
0 siblings, 1 reply; 2+ messages in thread
From: Naval Alcalá @ 2026-04-10 16:16 UTC (permalink / raw)
Cc: Naval Alcalá, David Woodhouse, Lu Baolu, Joerg Roedel,
Will Deacon, Robin Murphy, open list:INTEL IOMMU (VT-d),
open list
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.
This issue has been reported multiple times and remains
unresolved:
Link: https://lore.kernel.org/linux-iommu/20161205215841.GA20819@beast/
Link: https://bugzilla.kernel.org/show_bug.cgi?id=201185
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216064
Add the missing PCI ID to the existing quirk list to disable
DMAR for this device.
Signed-off-by: Naval Alcalá <ari@naval.cat>
---
drivers/iommu/intel/iommu.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index ef7613b177b9..8df0692e1fed 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3933,6 +3933,9 @@ 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);
--
2.51.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] iommu/vt-d: Disable DMAR for Intel Q35 IGFX
2026-04-10 16:16 [PATCH] iommu/vt-d: Disable DMAR for Intel Q35 IGFX Naval Alcalá
@ 2026-05-08 7:57 ` Baolu Lu
0 siblings, 0 replies; 2+ messages in thread
From: Baolu Lu @ 2026-05-08 7:57 UTC (permalink / raw)
To: Naval Alcalá
Cc: David Woodhouse, Joerg Roedel, Will Deacon, Robin Murphy,
open list:INTEL IOMMU (VT-d), open list
On 4/11/26 00:16, Naval Alcalá wrote:
> 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.
>
> This issue has been reported multiple times and remains
> unresolved:
> Link:https://lore.kernel.org/linux-iommu/20161205215841.GA20819@beast/
> Link:https://bugzilla.kernel.org/show_bug.cgi?id=201185
> Link:https://bugzilla.kernel.org/show_bug.cgi?id=216064
>
> Add the missing PCI ID to the existing quirk list to disable
> DMAR for this device.
>
> Signed-off-by: Naval Alcalá<ari@naval.cat>
> ---
> drivers/iommu/intel/iommu.c | 3 +++
> 1 file changed, 3 insertions(+)
Queued for v7.1-rc. Thanks!
^ permalink raw reply [flat|nested] 2+ messages in thread
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