Commit f007e99c authored by Weidong Han's avatar Weidong Han Committed by David Woodhouse
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Intel-IOMMU, intr-remap: source-id checking 



To support domain-isolation usages, the platform hardware must be
capable of uniquely identifying the requestor (source-id) for each
interrupt message. Without source-id checking for interrupt remapping
, a rouge guest/VM with assigned devices can launch interrupt attacks
to bring down anothe guest/VM or the VMM itself.

This patch adds source-id checking for interrupt remapping, and then
really isolates interrupts for guests/VMs with assigned devices.

Because PCI subsystem is not initialized yet when set up IOAPIC
entries, use read_pci_config_byte to access PCI config space directly.

Signed-off-by: default avatarWeidong Han <weidong.han@intel.com>
Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent c4658b4e

arch/x86/kernel/apic/io_apic.c

+6 −0
Original line number Diff line number Diff line
@@ -1414,6 +1414,9 @@ int setup_ioapic_entry(int apic_id, int irq, 
		irte.vector = vector;

		irte.dest_id = IRTE_DEST(destination);



		/* Set source-id of interrupt request */

		set_ioapic_sid(&irte, apic_id);



		modify_irte(irq, &irte);



		ir_entry->index2 = (index >> 15) & 0x1;
@@ -3290,6 +3293,9 @@ static int msi_compose_msg(struct pci_dev *pdev, unsigned int irq, struct msi_ms 
		irte.vector = cfg->vector;

		irte.dest_id = IRTE_DEST(dest);



		/* Set source-id of interrupt request */

		set_msi_sid(&irte, pdev);



		modify_irte(irq, &irte);



		msg->address_hi = MSI_ADDR_BASE_HI;

drivers/pci/intr_remapping.c

+117 −3
Original line number Diff line number Diff line
@@ -10,6 +10,8 @@ 
#include <linux/intel-iommu.h>

#include "intr_remapping.h"

#include <acpi/acpi.h>

#include <asm/pci-direct.h>

#include "pci.h"



static struct ioapic_scope ir_ioapic[MAX_IO_APICS];

static int ir_ioapic_num;
@@ -418,6 +420,91 @@ int free_irte(int irq) 
	return rc;

}



/*

 * source validation type

 */

#define SVT_NO_VERIFY		0x0  /* no verification is required */

#define SVT_VERIFY_SID_SQ	0x1  /* verify using SID and SQ fiels */

#define SVT_VERIFY_BUS		0x2  /* verify bus of request-id */



/*

 * source-id qualifier

 */

#define SQ_ALL_16	0x0  /* verify all 16 bits of request-id */

#define SQ_13_IGNORE_1	0x1  /* verify most significant 13 bits, ignore

			      * the third least significant bit

			      */

#define SQ_13_IGNORE_2	0x2  /* verify most significant 13 bits, ignore

			      * the second and third least significant bits

			      */

#define SQ_13_IGNORE_3	0x3  /* verify most significant 13 bits, ignore

			      * the least three significant bits

			      */



/*

 * set SVT, SQ and SID fields of irte to verify

 * source ids of interrupt requests

 */

static void set_irte_sid(struct irte *irte, unsigned int svt,

			 unsigned int sq, unsigned int sid)

{

	irte->svt = svt;

	irte->sq = sq;

	irte->sid = sid;

}



int set_ioapic_sid(struct irte *irte, int apic)

{

	int i;

	u16 sid = 0;



	if (!irte)

		return -1;



	for (i = 0; i < MAX_IO_APICS; i++) {

		if (ir_ioapic[i].id == apic) {

			sid = (ir_ioapic[i].bus << 8) | ir_ioapic[i].devfn;

			break;

		}

	}



	if (sid == 0) {

		pr_warning("Failed to set source-id of IOAPIC (%d)\n", apic);

		return -1;

	}



	set_irte_sid(irte, 1, 0, sid);



	return 0;

}



int set_msi_sid(struct irte *irte, struct pci_dev *dev)

{

	struct pci_dev *bridge;



	if (!irte || !dev)

		return -1;



	/* PCIe device or Root Complex integrated PCI device */

	if (dev->is_pcie || !dev->bus->parent) {

		set_irte_sid(irte, SVT_VERIFY_SID_SQ, SQ_ALL_16,

			     (dev->bus->number << 8) | dev->devfn);

		return 0;

	}



	bridge = pci_find_upstream_pcie_bridge(dev);

	if (bridge) {

		if (bridge->is_pcie) /* this is a PCIE-to-PCI/PCIX bridge */

			set_irte_sid(irte, SVT_VERIFY_BUS, SQ_ALL_16,

				(bridge->bus->number << 8) | dev->bus->number);

		else /* this is a legacy PCI bridge */

			set_irte_sid(irte, SVT_VERIFY_SID_SQ, SQ_ALL_16,

				(bridge->bus->number << 8) | bridge->devfn);

	}



	return 0;

}



static void iommu_set_intr_remapping(struct intel_iommu *iommu, int mode)

{

	u64 addr;
@@ -624,6 +711,35 @@ error: 
	return -1;

}



static void ir_parse_one_ioapic_scope(struct acpi_dmar_device_scope *scope,

				      struct intel_iommu *iommu)

{

	struct acpi_dmar_pci_path *path;

	u8 bus;

	int count;



	bus = scope->bus;

	path = (struct acpi_dmar_pci_path *)(scope + 1);

	count = (scope->length - sizeof(struct acpi_dmar_device_scope))

		/ sizeof(struct acpi_dmar_pci_path);



	while (--count > 0) {

		/*

		 * Access PCI directly due to the PCI

		 * subsystem isn't initialized yet.

		 */

		bus = read_pci_config_byte(bus, path->dev, path->fn,

					   PCI_SECONDARY_BUS);

		path++;

	}



	ir_ioapic[ir_ioapic_num].bus   = bus;

	ir_ioapic[ir_ioapic_num].devfn = PCI_DEVFN(path->dev, path->fn);

	ir_ioapic[ir_ioapic_num].iommu = iommu;

	ir_ioapic[ir_ioapic_num].id    = scope->enumeration_id;

	ir_ioapic_num++;

}



static int ir_parse_ioapic_scope(struct acpi_dmar_header *header,

				 struct intel_iommu *iommu)

{
@@ -648,9 +764,7 @@ static int ir_parse_ioapic_scope(struct acpi_dmar_header *header, 
			       " 0x%Lx\n", scope->enumeration_id,

			       drhd->address);



			ir_ioapic[ir_ioapic_num].iommu = iommu;

			ir_ioapic[ir_ioapic_num].id = scope->enumeration_id;

			ir_ioapic_num++;

			ir_parse_one_ioapic_scope(scope, iommu);

		}

		start += scope->length;

	}

drivers/pci/intr_remapping.h

+2 −0
Original line number Diff line number Diff line
@@ -3,6 +3,8 @@ 
struct ioapic_scope {

	struct intel_iommu *iommu;

	unsigned int id;

	unsigned int bus;	/* PCI bus number */

	unsigned int devfn;	/* PCI devfn number */

};



#define IR_X2APIC_MODE(mode) (mode ? (1 << 11) : 0)

include/linux/dmar.h

+11 −0
Original line number Diff line number Diff line
@@ -126,6 +126,8 @@ extern int free_irte(int irq); 
extern int irq_remapped(int irq);

extern struct intel_iommu *map_dev_to_ir(struct pci_dev *dev);

extern struct intel_iommu *map_ioapic_to_ir(int apic);

extern int set_ioapic_sid(struct irte *irte, int apic);

extern int set_msi_sid(struct irte *irte, struct pci_dev *dev);

#else

static inline int alloc_irte(struct intel_iommu *iommu, int irq, u16 count)

{
@@ -156,6 +158,15 @@ static inline struct intel_iommu *map_ioapic_to_ir(int apic) 
{

	return NULL;

}

static inline int set_ioapic_sid(struct irte *irte, int apic)

{

	return 0;

}

static inline int set_msi_sid(struct irte *irte, struct pci_dev *dev)

{

	return 0;

}



#define irq_remapped(irq)		(0)

#define enable_intr_remapping(mode)	(-1)

#define disable_intr_remapping()	(0)

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