Commit a59b50e9 authored by Joseph Cihula's avatar Joseph Cihula Committed by H. Peter Anvin
Browse files

intel_txt: Force IOMMU on for Intel TXT launch 



The tboot module will DMA protect all of memory in order to ensure the that
kernel will be able to initialize without compromise (from DMA).  Consequently,
the kernel must enable Intel Virtualization Technology for Directed I/O
(VT-d or Intel IOMMU) in order to replace this broad protection with the
appropriate page-granular protection.  Otherwise DMA devices will be unable
to read or write from memory and the kernel will eventually panic.

Because runtime IOMMU support is configurable by command line options, this
patch will force it to be enabled regardless of the options specified, and will
log a message if it was required to force it on.

 dmar.c        |    7 +++++++
 intel-iommu.c |   17 +++++++++++++++--
 2 files changed, 22 insertions(+), 2 deletions(-)

Signed-off-by: default avatarJoseph Cihula <joseph.cihula@intel.com>
Signed-off-by: default avatarShane Wang <shane.wang@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 86886e55

drivers/pci/dmar.c

+7 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <linux/timer.h>

#include <linux/irq.h>

#include <linux/interrupt.h>

#include <asm/tboot.h>



#undef PREFIX

#define PREFIX "DMAR:"
@@ -413,6 +414,12 @@ parse_dmar_table(void) 
	 */

	dmar_table_detect();



	/*

	 * ACPI tables may not be DMA protected by tboot, so use DMAR copy

	 * SINIT saved in SinitMleData in TXT heap (which is DMA protected)

	 */

	dmar_tbl = tboot_get_dmar_table(dmar_tbl);



	dmar = (struct acpi_table_dmar *)dmar_tbl;

	if (!dmar)

		return -ENODEV;

drivers/pci/intel-iommu.c

+15 −2
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ 
#include <linux/intel-iommu.h>

#include <linux/sysdev.h>

#include <asm/cacheflush.h>

#include <asm/tboot.h>

#include <asm/iommu.h>

#include "pci.h"
@@ -3183,12 +3184,22 @@ static int __init init_iommu_sysfs(void) 
int __init intel_iommu_init(void)

{

	int ret = 0;

	int force_on = 0;



	if (dmar_table_init())

	/* VT-d is required for a TXT/tboot launch, so enforce that */

	force_on = tboot_force_iommu();



	if (dmar_table_init()) {

		if (force_on)

			panic("tboot: Failed to initialize DMAR table\n");

		return 	-ENODEV;

	}



	if (dmar_dev_scope_init())

	if (dmar_dev_scope_init()) {

		if (force_on)

			panic("tboot: Failed to initialize DMAR device scope\n");

		return 	-ENODEV;

	}



	/*

	 * Check the need for DMA-remapping initialization now.
@@ -3204,6 +3215,8 @@ int __init intel_iommu_init(void) 


	ret = init_dmars();

	if (ret) {

		if (force_on)

			panic("tboot: Failed to initialize DMARs\n");

		printk(KERN_ERR "IOMMU: dmar init failed\n");

		put_iova_domain(&reserved_iova_list);

		iommu_exit_mempool();

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