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authorLinus Torvalds <torvalds@linux-foundation.org>2015-06-12 21:28:57 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-06-12 21:28:57 +0300
commitc39f3bc659b6f32e0e88113ec359a504be259e4f (patch)
tree2eb1ddf4f039dda7fed72f57162df3561e78214a /drivers
parentdf5f4158415b6fc4a2d683c6fdc806be6da176bc (diff)
parentc83b2f20fdde578bded3dfc4405c5db7a039c694 (diff)
downloadlinux-c39f3bc659b6f32e0e88113ec359a504be259e4f.tar.xz
Merge git://git.infradead.org/intel-iommu
Pull VT-d hardware workarounds from David Woodhouse: "This contains a workaround for hardware issues which I *thought* were never going to be seen on production hardware. I'm glad I checked that before the 4.1 release... Firstly, PASID support is so broken on existing chips that we're just going to declare the old capability bit 28 as 'reserved' and change the VT-d spec to move PASID support to another bit. So any existing hardware doesn't support SVM; it only sets that (now) meaningless bit 28. That patch *wasn't* imperative for 4.1 because we don't have PASID support yet. But *even* the extended context tables are broken — if you just enable the wider tables and use none of the new bits in them, which is precisely what 4.1 does, you find that translations don't work. It's this problem which I thought was caught in time to be fixed before production, but wasn't. To avoid triggering this issue, we now *only* enable the extended context tables on hardware which also advertises "we have PASID support and we actually tested it this time" with the new PASID feature bit. In addition, I've added an 'intel_iommu=ecs_off' command line parameter to allow us to disable it manually if we need to" * git://git.infradead.org/intel-iommu: iommu/vt-d: Only enable extended context tables if PASID is supported iommu/vt-d: Change PASID support to bit 40 of Extended Capability Register
Diffstat (limited to 'drivers')
-rw-r--r--drivers/iommu/intel-iommu.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 2ffe58969944..5ecfaf29933a 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -422,6 +422,14 @@ static int dmar_map_gfx = 1;
static int dmar_forcedac;
static int intel_iommu_strict;
static int intel_iommu_superpage = 1;
+static int intel_iommu_ecs = 1;
+
+/* 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 ecs_enabled(iommu) (intel_iommu_ecs && ecap_ecs(iommu->ecap) && \
+ ecap_pasid(iommu->ecap))
int intel_iommu_gfx_mapped;
EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped);
@@ -465,6 +473,10 @@ static int __init intel_iommu_setup(char *str)
printk(KERN_INFO
"Intel-IOMMU: disable supported super page\n");
intel_iommu_superpage = 0;
+ } else if (!strncmp(str, "ecs_off", 7)) {
+ printk(KERN_INFO
+ "Intel-IOMMU: disable extended context table support\n");
+ intel_iommu_ecs = 0;
}
str += strcspn(str, ",");
@@ -669,7 +681,7 @@ static inline struct context_entry *iommu_context_addr(struct intel_iommu *iommu
struct context_entry *context;
u64 *entry;
- if (ecap_ecs(iommu->ecap)) {
+ if (ecs_enabled(iommu)) {
if (devfn >= 0x80) {
devfn -= 0x80;
entry = &root->hi;
@@ -806,7 +818,7 @@ static void free_context_table(struct intel_iommu *iommu)
if (context)
free_pgtable_page(context);
- if (!ecap_ecs(iommu->ecap))
+ if (!ecs_enabled(iommu))
continue;
context = iommu_context_addr(iommu, i, 0x80, 0);
@@ -1141,7 +1153,7 @@ static void iommu_set_root_entry(struct intel_iommu *iommu)
unsigned long flag;
addr = virt_to_phys(iommu->root_entry);
- if (ecap_ecs(iommu->ecap))
+ if (ecs_enabled(iommu))
addr |= DMA_RTADDR_RTT;
raw_spin_lock_irqsave(&iommu->register_lock, flag);