Commit 99b50be9 authored by Rajat Jain's avatar Rajat Jain Committed by Bjorn Helgaas
Browse files

PCI: Treat "external-facing" devices themselves as internal 

"External-facing" devices are internal devices that expose PCIe hierarchies
such as Thunderbolt outside the platform [1].  Previously these internal
devices were marked as "untrusted" the same as devices downstream from
them.

Use the ACPI or DT information to identify external-facing devices, but
only mark the devices *downstream* from them as "untrusted" [2].  The
external-facing device itself is no longer marked as untrusted.

[1] https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports#identifying-externally-exposed-pcie-root-ports
[2] https://lore.kernel.org/linux-pci/20200610230906.GA1528594@bjorn-Precision-5520/
Link: https://lore.kernel.org/r/20200707224604.3737893-3-rajatja@google.com


Signed-off-by: default avatarRajat Jain <rajatja@google.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 52fbf5bd

drivers/iommu/intel/iommu.c

+3 −3
Original line number Diff line number Diff line
@@ -4730,12 +4730,12 @@ const struct attribute_group *intel_iommu_groups[] = { 
	NULL,

};



static inline bool has_untrusted_dev(void)

static inline bool has_external_pci(void)

{

	struct pci_dev *pdev = NULL;



	for_each_pci_dev(pdev)

		if (pdev->untrusted)

		if (pdev->external_facing)

			return true;



	return false;
@@ -4743,7 +4743,7 @@ static inline bool has_untrusted_dev(void) 


static int __init platform_optin_force_iommu(void)

{

	if (!dmar_platform_optin() || no_platform_optin || !has_untrusted_dev())

	if (!dmar_platform_optin() || no_platform_optin || !has_external_pci())

		return 0;



	if (no_iommu || dmar_disabled)

drivers/pci/of.c

+1 −1
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ void pci_set_bus_of_node(struct pci_bus *bus) 
	} else {

		node = of_node_get(bus->self->dev.of_node);

		if (node && of_property_read_bool(node, "external-facing"))

			bus->self->untrusted = true;

			bus->self->external_facing = true;

	}



	bus->dev.of_node = node;

drivers/pci/pci-acpi.c

+4 −5
Original line number Diff line number Diff line
@@ -1213,7 +1213,7 @@ static void pci_acpi_optimize_delay(struct pci_dev *pdev, 
	ACPI_FREE(obj);

}



static void pci_acpi_set_untrusted(struct pci_dev *dev)

static void pci_acpi_set_external_facing(struct pci_dev *dev)

{

	u8 val;
@@ -1224,11 +1224,10 @@ static void pci_acpi_set_untrusted(struct pci_dev *dev) 


	/*

	 * These root ports expose PCIe (including DMA) outside of the

	 * system so make sure we treat them and everything behind as

	 * untrusted.

	 * system.  Everything downstream from them is external.

	 */

	if (val)

		dev->untrusted = 1;

		dev->external_facing = 1;

}



static void pci_acpi_setup(struct device *dev)
@@ -1240,7 +1239,7 @@ static void pci_acpi_setup(struct device *dev) 
		return;



	pci_acpi_optimize_delay(pci_dev, adev->handle);

	pci_acpi_set_untrusted(pci_dev);

	pci_acpi_set_external_facing(pci_dev);

	pci_acpi_add_edr_notifier(pci_dev);



	pci_acpi_add_pm_notifier(adev, pci_dev);

drivers/pci/probe.c

+1 −1
Original line number Diff line number Diff line
@@ -1552,7 +1552,7 @@ static void set_pcie_untrusted(struct pci_dev *dev) 
	 * untrusted as well.

	 */

	parent = pci_upstream_bridge(dev);

	if (parent && parent->untrusted)

	if (parent && (parent->untrusted || parent->external_facing))

		dev->untrusted = true;

}

include/linux/pci.h

+6 −0
Original line number Diff line number Diff line
@@ -432,6 +432,12 @@ struct pci_dev { 
	 * mappings to make sure they cannot access arbitrary memory.

	 */

	unsigned int	untrusted:1;

	/*

	 * Info from the platform, e.g., ACPI or device tree, may mark a

	 * device as "external-facing".  An external-facing device is

	 * itself internal but devices downstream from it are external.

	 */

	unsigned int	external_facing:1;

	unsigned int	broken_intx_masking:1;	/* INTx masking can't be used */

	unsigned int	io_window_1k:1;		/* Intel bridge 1K I/O windows */

	unsigned int	irq_managed:1;

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