iommu/vt-d: Implement deferred invalidate for SVM

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

drivers/iommu/intel-iommu.c

@@ -4981,6 +4981,8 @@ int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct intel_svm_dev *sd
 				ctx_lo |= CONTEXT_TT_PT_PASID << 2;
 		}
 		ctx_lo |= CONTEXT_PASIDE;
+		if (iommu->pasid_state_table)
+			ctx_lo |= CONTEXT_DINVE;
 		context[0].lo = ctx_lo;
 		wmb();
 		iommu->flush.flush_context(iommu, sdev->did, sdev->sid,

drivers/iommu/intel-svm.c

@@ -26,6 +26,10 @@ struct pasid_entry {
 	u64 val;
 };
 
+struct pasid_state_entry {
+	u64 val;
+};
+
 int intel_svm_alloc_pasid_tables(struct intel_iommu *iommu)
 {
 	struct page *pages;
@@ -127,6 +131,11 @@ static void intel_flush_svm_range(struct intel_svm *svm, unsigned long address,
 {
 	struct intel_svm_dev *sdev;
 
+	/* Try deferred invalidate if available */
+	if (svm->iommu->pasid_state_table &&
+	    !cmpxchg64(&svm->iommu->pasid_state_table[svm->pasid].val, 0, 1ULL << 63))
+		return;
+
 	rcu_read_lock();
 	list_for_each_entry_rcu(sdev, &svm->devs, list)
 		intel_flush_svm_range_dev(svm, sdev, address, pages, ih);

include/linux/dma_remapping.h

@@ -25,6 +25,7 @@
 #define CONTEXT_TT_PT_PASID_DEV_IOTLB 5
 #define CONTEXT_TT_MASK (7ULL << 2)
 
+#define CONTEXT_DINVE		(1ULL << 8)
 #define CONTEXT_PRS		(1ULL << 9)
 #define CONTEXT_PASIDE		(1ULL << 11)