Re: çå: [PATCH] iommu/vt-d: Don't reject nvme host due to scope mismatch

[Lu Baolu]

Hi,

On 2019/12/23 15:59, Jim,Yan wrote:
> > -----éäåä-----
> > åää: Jerry Snitselaar [mailto:jsnitsel@xxxxxxxxxx]
> > åéæé: 2019å12æ20æ 17:23
> > æää: Jim,Yan <jimyan@xxxxxxxxx>
> > æé: joro@xxxxxxxxxx; iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx;
> > linux-kernel@xxxxxxxxxxxxxxx
> > äé: Re: [PATCH] iommu/vt-d: Don't reject nvme host due to scope mismatch
> >
> > On Fri Dec 20 19, jimyan wrote:
> > > On a system with an Intel PCIe port configured as a nvme host device,
> > > iommu initialization fails with
> > >
> > >     DMAR: Device scope type does not match for 0000:80:00.0
> > >
> > > This is because the DMAR table reports this device as having scope 2
> > > (ACPI_DMAR_SCOPE_TYPE_BRIDGE):
> >
> > Isn't that a problem to be fixed in the DMAR table then?
> >
> > > but the device has a type 0 PCI header:
> > > 80:00.0 Class 0600: Device 8086:2020 (rev 06)
> > > 00: 86 80 20 20 47 05 10 00 06 00 00 06 10 00 00 00
> > > 10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > > 20: 00 00 00 00 00 00 00 00 00 00 00 00 86 80 00 00
> > > 30: 00 00 00 00 90 00 00 00 00 00 00 00 00 01 00 00
> > >
> > > VT-d works perfectly on this system, so there's no reason to bail out
> > > on initialization due to this apparent scope mismatch. Add the class
> > > 0x600 ("PCI_CLASS_BRIDGE_HOST") as a heuristic for allowing DMAR
> > > initialization for non-bridge PCI devices listed with scope bridge.
> > >
> > > Signed-off-by: jimyan <jimyan@xxxxxxxxx>
> > > ---
> > > drivers/iommu/dmar.c | 1 +
> > > 1 file changed, 1 insertion(+)
> > >
> > > diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c index
> > > eecd6a421667..9faf2f0e0237 100644
> > > --- a/drivers/iommu/dmar.c
> > > +++ b/drivers/iommu/dmar.c
> > > @@ -244,6 +244,7 @@ int dmar_insert_dev_scope(struct
> > dmar_pci_notify_info *info,
> > > 		     info->dev->hdr_type != PCI_HEADER_TYPE_NORMAL) ||
> > > 		    (scope->entry_type == ACPI_DMAR_SCOPE_TYPE_BRIDGE &&
> > > 		     (info->dev->hdr_type == PCI_HEADER_TYPE_NORMAL &&
> > > +			  info->dev->class >> 8 != PCI_CLASS_BRIDGE_HOST &&
> > > 		      info->dev->class >> 8 != PCI_CLASS_BRIDGE_OTHER))) {
> > > 			pr_warn("Device scope type does not match for %s\n",
> > > 				pci_name(info->dev));
> > > --
> > > 2.11.0
> > >
> > > _______________________________________________
> > > iommu mailing list
> > > iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > > https://lists.linuxfoundation.org/mailman/listinfo/iommu
> Actually this patch is similar to the commit: ffb2d1eb88c3("iommu/vt-d: Don't reject NTB devices due to scope mismatch"). Besides, modifying DMAR table need OEM update BIOS. It is hard to implement.

For both cases, a quirk flag seems to be more reasonable, so that
unrelated devices will not be impacted.

Best regards,
baolu