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IOMMU Fixes for Linux v4.18-rc5: 

Only one revert:
 
 	* Revert an Intel VT-d patch that caused issues with the i915 GPU
 	  driver
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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"
This commit is contained in:
Linus Torvalds 2018-07-20 11:43:21 -07:00
parent de87dcdedc 2db1581e1f
commit 47736af324
2 changed files with 31 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/iommu/intel-iommu.c
View File

@ -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");

1
include/linux/intel-iommu.h
View File

@ -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)