On Fri, Mar 25, 2022 at 7:46 PM Rajat Jain <rajatja@xxxxxxxxxx> wrote: > > The "DmaProperty" is supported and documented by Microsoft here: > https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports > They use this property for DMA protection: > https://docs.microsoft.com/en-us/windows/security/information-protection/kernel-dma-protection-for-thunderbolt > > Support the "DmaProperty" with the same semantics. This is useful for > internal PCI devices that do not hang off a PCIe rootport, but offer > an attack surface for DMA attacks (e.g. internal network devices). > > Signed-off-by: Rajat Jain <rajatja@xxxxxxxxxx> > Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > --- > v5: * Reorder the patches in the series > v4: * Add the GUID. > * Update the comment and commitlog. > v3: * Use Microsoft's documented property "DmaProperty" > * Resctrict to ACPI only > > drivers/acpi/property.c | 3 +++ > drivers/pci/pci-acpi.c | 16 ++++++++++++++++ > 2 files changed, 19 insertions(+) > > diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c > index d0986bda2964..20603cacc28d 100644 > --- a/drivers/acpi/property.c > +++ b/drivers/acpi/property.c > @@ -48,6 +48,9 @@ static const guid_t prp_guids[] = { > /* Storage device needs D3 GUID: 5025030f-842f-4ab4-a561-99a5189762d0 */ > GUID_INIT(0x5025030f, 0x842f, 0x4ab4, > 0xa5, 0x61, 0x99, 0xa5, 0x18, 0x97, 0x62, 0xd0), > + /* DmaProperty for PCI devices GUID: 70d24161-6dd5-4c9e-8070-705531292865 */ > + GUID_INIT(0x70d24161, 0x6dd5, 0x4c9e, > + 0x80, 0x70, 0x70, 0x55, 0x31, 0x29, 0x28, 0x65), > }; > > /* ACPI _DSD data subnodes GUID: dbb8e3e6-5886-4ba6-8795-1319f52a966b */ > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c > index 1f15ab7eabf8..378e05096c52 100644 > --- a/drivers/pci/pci-acpi.c > +++ b/drivers/pci/pci-acpi.c > @@ -1350,12 +1350,28 @@ static void pci_acpi_set_external_facing(struct pci_dev *dev) > dev->external_facing = 1; > } > > +static void pci_acpi_check_for_dma_protection(struct pci_dev *dev) > +{ > + u8 val; > + > + /* > + * Property also used by Microsoft Windows for same purpose, > + * (to implement DMA protection from a device, using the IOMMU). > + */ > + if (device_property_read_u8(&dev->dev, "DmaProperty", &val)) > + return; > + > + if (val) > + dev->untrusted = 1; > +} > + > void pci_acpi_setup(struct device *dev, struct acpi_device *adev) > { > struct pci_dev *pci_dev = to_pci_dev(dev); > > pci_acpi_optimize_delay(pci_dev, adev->handle); > pci_acpi_set_external_facing(pci_dev); > + pci_acpi_check_for_dma_protection(pci_dev); > pci_acpi_add_edr_notifier(pci_dev); > > pci_acpi_add_pm_notifier(adev, pci_dev); > -- > 2.35.1.1021.g381101b075-goog >
