| Message ID | 20230226000822.42384-1-marmarek@invisiblethingslab.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | IOMMU/VT-d: Fix iommu=no-igfx if the IOMMU scope contains phantom device | expand |
On 26.02.2023 01:08, Marek Marczykowski-Górecki wrote: > If the scope for IGD's IOMMU contains additional device that doesn't > actually exist, iommu=no-igfx would not disable that IOMMU. In this > particular case (Thinkpad x230) it included > 00:02.1, but there is no such device on this platform. > Consider only existing devices for "gfx only" check. > Hmm, perhaps Fixes: 2d7f191b392e ('VT-d: generalize and correct "iommu=no-igfx" handling') ? > Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> > --- > I have looked at existence check acpi_parse_one_drhd(), but re-using > that one wouldn't work for two reasons: > - gfx_only logic is very much tied to acpi_parse_dev_scope() I think this one could be dealt with, but ... > - pci_device_detect() in acpi_parse_one_drhd() is skipped in case of > (implicit or explicit) iommu=force ... I agree this is a good reason to put the check in acpi_parse_dev_scope(). > --- a/xen/drivers/passthrough/vtd/dmar.c > +++ b/xen/drivers/passthrough/vtd/dmar.c > @@ -396,6 +396,7 @@ static int __init acpi_parse_dev_scope( > igd_drhd_address = drhd->address; > > if ( gfx_only && > + pci_device_detect(seg, bus, path->dev, path->fn) && > pci_conf_read8(PCI_SBDF(seg, bus, path->dev, path->fn), > PCI_CLASS_DEVICE + 1) != 0x03 > /* PCI_BASE_CLASS_DISPLAY */ ) If we're adding an existence check, then maybe better in the surrounding if(): Setting igd_drhd_address when there's not really a device at the designated address isn't very sensible either. (In fact I think I'm going to alter the inner part of that if() again as well.) Jan
diff --git a/xen/drivers/passthrough/vtd/dmar.c b/xen/drivers/passthrough/vtd/dmar.c index 78c8bad1515a..3b5e152901b9 100644 --- a/xen/drivers/passthrough/vtd/dmar.c +++ b/xen/drivers/passthrough/vtd/dmar.c @@ -396,6 +396,7 @@ static int __init acpi_parse_dev_scope( igd_drhd_address = drhd->address; if ( gfx_only && + pci_device_detect(seg, bus, path->dev, path->fn) && pci_conf_read8(PCI_SBDF(seg, bus, path->dev, path->fn), PCI_CLASS_DEVICE + 1) != 0x03 /* PCI_BASE_CLASS_DISPLAY */ )
If the scope for IGD's IOMMU contains additional device that doesn't actually exist, iommu=no-igfx would not disable that IOMMU. In this particular case (Thinkpad x230) it included 00:02.1, but there is no such device on this platform. Consider only existing devices for "gfx only" check. Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> --- I have looked at existence check acpi_parse_one_drhd(), but re-using that one wouldn't work for two reasons: - gfx_only logic is very much tied to acpi_parse_dev_scope() - pci_device_detect() in acpi_parse_one_drhd() is skipped in case of (implicit or explicit) iommu=force --- xen/drivers/passthrough/vtd/dmar.c | 1 + 1 file changed, 1 insertion(+)