On Wed, Feb 9, 2022 at 8:11 PM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
>
> On Wed, Feb 2, 2022 at 3:01 AM Rajat Jain <rajatja@xxxxxxxxxx> wrote:
> >
> > Today the pci_dev->untrusted is set for any devices sitting downstream
> > an external facing port (determined via "ExternalFacingPort" or the
> > "external-facing" properties).
> >
> > However, currently there is no way for internal devices to be marked as
> > untrusted.
> >
> > There are use-cases though, where a platform would like to treat an
> > internal device as untrusted (perhaps because it runs untrusted firmware
> > or offers an attack surface by handling untrusted network data etc).
> >
> > Introduce a new "UntrustedDevice" property that can be used by the
> > firmware to mark any device as untrusted.
> >
> > Signed-off-by: Rajat Jain <rajatja@xxxxxxxxxx>
> > ---
> > v2: * Also use the same property for device tree based systems.
> > * Add documentation (next patch)
> >
> > drivers/pci/of.c | 2 ++
> > drivers/pci/pci-acpi.c | 1 +
> > drivers/pci/pci.c | 9 +++++++++
> > drivers/pci/pci.h | 2 ++
> > 4 files changed, 14 insertions(+)
> >
> > diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> > index cb2e8351c2cc..e8b804664b69 100644
> > --- a/drivers/pci/of.c
> > +++ b/drivers/pci/of.c
> > @@ -24,6 +24,8 @@ void pci_set_of_node(struct pci_dev *dev)
> > dev->devfn);
> > if (dev->dev.of_node)
> > dev->dev.fwnode = &dev->dev.of_node->fwnode;
> > +
> > + pci_set_untrusted(dev);
> > }
> >
> > void pci_release_of_node(struct pci_dev *dev)
> > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> > index a42dbf448860..2bffbd5c6114 100644
> > --- a/drivers/pci/pci-acpi.c
> > +++ b/drivers/pci/pci-acpi.c
> > @@ -1356,6 +1356,7 @@ void pci_acpi_setup(struct device *dev, struct acpi_device *adev)
> >
> > pci_acpi_optimize_delay(pci_dev, adev->handle);
> > pci_acpi_set_external_facing(pci_dev);
> > + pci_set_untrusted(pci_dev);
> > pci_acpi_add_edr_notifier(pci_dev);
> >
> > pci_acpi_add_pm_notifier(adev, pci_dev);
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 9ecce435fb3f..41e887c27004 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -6869,3 +6869,12 @@ static int __init pci_realloc_setup_params(void)
> > return 0;
> > }
> > pure_initcall(pci_realloc_setup_params);
> > +
> > +void pci_set_untrusted(struct pci_dev *pdev)
> > +{
> > + u8 val;
> > +
> > + if (!device_property_read_u8(&pdev->dev, "UntrustedDevice", &val)
> > + && val)
> > + pdev->untrusted = 1;
>
> I'm not sure why you ignore val = 0. Is it not a valid value?
>
> The property is not particularly well defined here. It is not clear
> from its name that it only applies to PCI devices and how.
>
> AFAICS, the "untrusted" bit affected by it is only used by the ATS
> code and in one PCH ACS quirk, but I'm not sure if this is all you
> have in mind.
Besides, sort of in the bikeshedding territory, its name doesn't
follow the guidelines given in the _DSD guide:
https://github.com/UEFI/DSD-Guide/blob/main/dsd-guide.pdf
I do realize that you want it to be valid for both ACPI and DT, but
that doesn't preclude following the guidelines AFAICS.
> > +}
> > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> > index 3d60cabde1a1..6c273ce5e0ba 100644
> > --- a/drivers/pci/pci.h
> > +++ b/drivers/pci/pci.h
> > @@ -761,4 +761,6 @@ static inline pci_power_t mid_pci_get_power_state(struct pci_dev *pdev)
> > }
> > #endif
> >
> > +void pci_set_untrusted(struct pci_dev *pdev);
> > +
> > #endif /* DRIVERS_PCI_H */
> > --
> > 2.35.0.rc2.247.g8bbb082509-goog
> >
