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Commit 47736af3 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'iommu-fixes-v4.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu 

Pull IOMMU fix from Joerg Roedel:
 "Only one revert, for an an Intel VT-d patch that caused issues with
  the i915 GPU driver"

* tag 'iommu-fixes-v4.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  Revert "iommu/vt-d: Clean up pasid quirk for pre-production devices"
parents de87dcde 2db1581e

drivers/iommu/intel-iommu.c

+30 −2
Original line number Diff line number Diff line
@@ -484,14 +484,37 @@ static int dmar_forcedac; 
static int intel_iommu_strict;

static int intel_iommu_superpage = 1;

static int intel_iommu_ecs = 1;

static int intel_iommu_pasid28;

static int iommu_identity_mapping;



#define IDENTMAP_ALL		1

#define IDENTMAP_GFX		2

#define IDENTMAP_AZALIA		4



#define ecs_enabled(iommu)	(intel_iommu_ecs && ecap_ecs(iommu->ecap))

#define pasid_enabled(iommu)	(ecs_enabled(iommu) && ecap_pasid(iommu->ecap))

/* Broadwell and Skylake have broken ECS support — normal so-called "second

 * level" translation of DMA requests-without-PASID doesn't actually happen

 * unless you also set the NESTE bit in an extended context-entry. Which of

 * course means that SVM doesn't work because it's trying to do nested

 * translation of the physical addresses it finds in the process page tables,

 * through the IOVA->phys mapping found in the "second level" page tables.

 *

 * The VT-d specification was retroactively changed to change the definition

 * of the capability bits and pretend that Broadwell/Skylake never happened...

 * but unfortunately the wrong bit was changed. It's ECS which is broken, but

 * for some reason it was the PASID capability bit which was redefined (from

 * bit 28 on BDW/SKL to bit 40 in future).

 *

 * So our test for ECS needs to eschew those implementations which set the old

 * PASID capabiity bit 28, since those are the ones on which ECS is broken.

 * Unless we are working around the 'pasid28' limitations, that is, by putting

 * the device into passthrough mode for normal DMA and thus masking the bug.

 */

#define ecs_enabled(iommu) (intel_iommu_ecs && ecap_ecs(iommu->ecap) && \

			    (intel_iommu_pasid28 || !ecap_broken_pasid(iommu->ecap)))

/* PASID support is thus enabled if ECS is enabled and *either* of the old

 * or new capability bits are set. */

#define pasid_enabled(iommu) (ecs_enabled(iommu) &&			\

			      (ecap_pasid(iommu->ecap) || ecap_broken_pasid(iommu->ecap)))



int intel_iommu_gfx_mapped;

EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped);
@@ -554,6 +577,11 @@ static int __init intel_iommu_setup(char *str) 
			printk(KERN_INFO

				"Intel-IOMMU: disable extended context table support\n");

			intel_iommu_ecs = 0;

		} else if (!strncmp(str, "pasid28", 7)) {

			printk(KERN_INFO

				"Intel-IOMMU: enable pre-production PASID support\n");

			intel_iommu_pasid28 = 1;

			iommu_identity_mapping |= IDENTMAP_GFX;

		} else if (!strncmp(str, "tboot_noforce", 13)) {

			printk(KERN_INFO

				"Intel-IOMMU: not forcing on after tboot. This could expose security risk for tboot\n");

include/linux/intel-iommu.h

+1 −0
Original line number Diff line number Diff line
@@ -121,6 +121,7 @@ 
#define ecap_srs(e)		((e >> 31) & 0x1)

#define ecap_ers(e)		((e >> 30) & 0x1)

#define ecap_prs(e)		((e >> 29) & 0x1)

#define ecap_broken_pasid(e)	((e >> 28) & 0x1)

#define ecap_dis(e)		((e >> 27) & 0x1)

#define ecap_nest(e)		((e >> 26) & 0x1)

#define ecap_mts(e)		((e >> 25) & 0x1)