iommu/vt-d: Introduce intel_iommu=pasid28, and pasid_enabled() macro

As long as we use an identity mapping to work around the worst of the
hardware bugs which caused us to defeature it and change the definition
of the capability bit, we *can* use PASID support on the devices which
advertised it in bit 28 of the Extended Capability Register.

Allow people to do so with 'intel_iommu=pasid28' on the command line.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 17b4744628ab254dee2093e012b9a3a3a8fde971..6a01735f4df3973b676c4204ba556bda65236d11 100644 (file)
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -497,13 +497,21 @@ 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
 
 /* We only actually use ECS when PASID support (on the new bit 40)
  * is also advertised. Some early implementations — the ones with
  * PASID support on bit 28 — have issues even when we *only* use
  * extended root/context tables. */
+#define pasid_enabled(iommu) (ecap_pasid(iommu->ecap) || \
+                             (intel_iommu_pasid28 && ecap_broken_pasid(iommu->ecap)))
 #define ecs_enabled(iommu) (intel_iommu_ecs && ecap_ecs(iommu->ecap) && \
-                           ecap_pasid(iommu->ecap))
+                           pasid_enabled(iommu))
 
 int intel_iommu_gfx_mapped;
 EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped);
@@ -566,6 +574,11 @@ 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;
                }
 
                str += strcspn(str, ",");
@@ -2403,11 +2416,6 @@ found_domain:
        return domain;
 }
 
-static int iommu_identity_mapping;
-#define IDENTMAP_ALL           1
-#define IDENTMAP_GFX           2
-#define IDENTMAP_AZALIA                4
-
 static int iommu_domain_identity_map(struct dmar_domain *domain,
                                     unsigned long long start,
                                     unsigned long long end)

diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 08802b99f057fd6d0ce8f8d1a1a4437b54242a53..1d69c1d3aa9a50a4a3c4ccc421d7910cbaee9d3f 100644 (file)
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -121,7 +121,7 @@ static inline void dmar_writeq(void __iomem *addr, u64 val)
 #define ecap_srs(e)            ((e >> 31) & 0x1)
 #define ecap_ers(e)            ((e >> 30) & 0x1)
 #define ecap_prs(e)            ((e >> 29) & 0x1)
-/* PASID support used to be on bit 28 */
+#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)