| Message ID | 20161205215841.GA20819@beast (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 2016-12-05 at 13:58 -0800, Kees Cook wrote: > This blacklists the Q35 integrated graphics so IOMMU can be otherwise > enabled. Without this, a Q35 system can only enable IOMMU when booting > with "intel_iommu=on,igfx_off" but not "intel_iommu=on". Hm, is this definitely the same bug? Or is it something different, and perhaps a BIOS issue? There are many of those...
On Mon, Dec 5, 2016 at 2:07 PM, David Woodhouse <dwmw2@infradead.org> wrote: > On Mon, 2016-12-05 at 13:58 -0800, Kees Cook wrote: >> This blacklists the Q35 integrated graphics so IOMMU can be otherwise >> enabled. Without this, a Q35 system can only enable IOMMU when booting >> with "intel_iommu=on,igfx_off" but not "intel_iommu=on". > > Hm, is this definitely the same bug? Or is it something different, and > perhaps a BIOS issue? There are many of those... Hm, I have no idea. :) What would I look for in the BIOS? I figured since g4 was busted, surely q35 was too, since it's even older... -Kees
On Mon, 2016-12-05 at 14:18 -0800, Kees Cook wrote: > Hm, I have no idea. :) What would I look for in the BIOS? For a start, what is the actual failure mode? > I figured since g4 was busted, surely q35 was too, since it's even > older... Oh no, they all have different failures. Intel never actually *tested* their graphics hardware before shipping it, but IIRC it was only Q4x where we concluded the hardware was just too broken to live.
On Mon, Dec 5, 2016 at 2:47 PM, David Woodhouse <dwmw2@infradead.org> wrote: > On Mon, 2016-12-05 at 14:18 -0800, Kees Cook wrote: >> Hm, I have no idea. :) What would I look for in the BIOS? > > For a start, what is the actual failure mode? Based on initial testing (not that I've spent tons of time with it, since I need that machine running): at graphics init, entire system hangs. :P >> I figured since g4 was busted, surely q35 was too, since it's even >> older... > > Oh no, they all have different failures. Intel never actually *tested* > their graphics hardware before shipping it, but IIRC it was only Q4x > where we concluded the hardware was just too broken to live. Wheee! -Kees
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index d8376c2d18b3..24e5b06834ae 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -5327,6 +5327,7 @@ static void quirk_iommu_g4x_gfx(struct pci_dev *dev) dmar_map_gfx = 0; } +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x29b2, quirk_iommu_g4x_gfx); DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2a40, quirk_iommu_g4x_gfx); DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e00, quirk_iommu_g4x_gfx); DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e10, quirk_iommu_g4x_gfx);
This blacklists the Q35 integrated graphics so IOMMU can be otherwise enabled. Without this, a Q35 system can only enable IOMMU when booting with "intel_iommu=on,igfx_off" but not "intel_iommu=on". 00:02.0 0300: 8086:29b2 (rev 02) (prog-if 00 [VGA controller]) Subsystem: 8086:4f4a Flags: bus master, fast devsel, latency 0, IRQ 32 Memory at e0380000 (32-bit, non-prefetchable) [size=512K] I/O ports at 2460 [size=8] Memory at d0000000 (32-bit, prefetchable) [size=256M] Memory at e0200000 (32-bit, non-prefetchable) [size=1M] Expansion ROM at <unassigned> [disabled] Capabilities: <access denied> Kernel driver in use: i915 Kernel modules: i915 Signed-off-by: Kees Cook <keescook@chromium.org> --- drivers/iommu/intel-iommu.c | 1 + 1 file changed, 1 insertion(+)