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Wysocki" , Len Brown , linux-pci@vger.kernel.org, Mika Westerberg , Greg Kroah-Hartman , Bjorn Helgaas , Bjorn Helgaas , ACPI Devel Maling List , Linux Kernel Mailing List , Rajat Jain , Dmitry Torokhov , Jesse Barnes , Jean-Philippe Brucker , Pavel Machek , "Oliver O'Halloran" , Joerg Roedel , Will Deacon , David Woodhouse , Lu Baolu , iommu@lists.linux-foundation.org Cc: Rajat Jain X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Rajat Jain via iommu Reply-To: Rajat Jain Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" 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 --- v4: * Add the GUID. * Use the (now) renamed property - pci_dev->poses_dma_risk) * 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..5360f1af2ed3 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->poses_dma_risk = 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); -- 2.35.1.894.gb6a874cedc-goog _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu