linux-kernel - [PATCH 3/4] iommu/vt-d: Clean up pasid quirk for pre-production devices

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Date:   Fri,  4 May 2018 13:08:18 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     ashok.raj@...el.com, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 3/4] iommu/vt-d: Clean up pasid quirk for pre-production devices

The pasid28 quirk is needed only for some pre-production devices.
Remove it to make the code concise.

Signed-off-by: Ashok Raj <ashok.raj@...el.com>
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel-iommu.c | 32 ++------------------------------
 include/linux/intel-iommu.h |  1 -
 2 files changed, 2 insertions(+), 31 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 9064607..10bce33 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -485,37 +485,14 @@ 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
 
-/* 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)))
+#define ecs_enabled(iommu)	(intel_iommu_ecs && ecap_ecs(iommu->ecap))
+#define pasid_enabled(iommu)	(ecs_enabled(iommu) && ecap_pasid(iommu->ecap))
 
 int intel_iommu_gfx_mapped;
 EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped);
@@ -578,11 +555,6 @@ 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");
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index ef169d6..1df9401 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -121,7 +121,6 @@
 #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)
-- 
2.7.4