iommu/vt-d: Factor out helpers from domain_context_mapping_one()

Extract common code from domain_context_mapping_one() into new helpers,
making it reusable by other functions such as the upcoming identity domain
implementation. No intentional functional changes.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Link: https://lore.kernel.org/r/20240809055431.36513-6-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel/iommu.c

@@ -1597,6 +1597,61 @@ static void domain_exit(struct dmar_domain *domain)
 	kfree(domain);
 }
 
+/*
+ * For kdump cases, old valid entries may be cached due to the
+ * in-flight DMA and copied pgtable, but there is no unmapping
+ * behaviour for them, thus we need an explicit cache flush for
+ * the newly-mapped device. For kdump, at this point, the device
+ * is supposed to finish reset at its driver probe stage, so no
+ * in-flight DMA will exist, and we don't need to worry anymore
+ * hereafter.
+ */
+static void copied_context_tear_down(struct intel_iommu *iommu,
+				     struct context_entry *context,
+				     u8 bus, u8 devfn)
+{
+	u16 did_old;
+
+	if (!context_copied(iommu, bus, devfn))
+		return;
+
+	assert_spin_locked(&iommu->lock);
+
+	did_old = context_domain_id(context);
+	context_clear_entry(context);
+
+	if (did_old < cap_ndoms(iommu->cap)) {
+		iommu->flush.flush_context(iommu, did_old,
+					   (((u16)bus) << 8) | devfn,
+					   DMA_CCMD_MASK_NOBIT,
+					   DMA_CCMD_DEVICE_INVL);
+		iommu->flush.flush_iotlb(iommu, did_old, 0, 0,
+					 DMA_TLB_DSI_FLUSH);
+	}
+
+	clear_context_copied(iommu, bus, devfn);
+}
+
+/*
+ * It's a non-present to present mapping. If hardware doesn't cache
+ * non-present entry we only need to flush the write-buffer. If the
+ * _does_ cache non-present entries, then it does so in the special
+ * domain #0, which we have to flush:
+ */
+static void context_present_cache_flush(struct intel_iommu *iommu, u16 did,
+					u8 bus, u8 devfn)
+{
+	if (cap_caching_mode(iommu->cap)) {
+		iommu->flush.flush_context(iommu, 0,
+					   (((u16)bus) << 8) | devfn,
+					   DMA_CCMD_MASK_NOBIT,
+					   DMA_CCMD_DEVICE_INVL);
+		iommu->flush.flush_iotlb(iommu, did, 0, 0, DMA_TLB_DSI_FLUSH);
+	} else {
+		iommu_flush_write_buffer(iommu);
+	}
+}
+
 static int domain_context_mapping_one(struct dmar_domain *domain,
 				      struct intel_iommu *iommu,
 				      u8 bus, u8 devfn)
@@ -1625,31 +1680,9 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
 	if (context_present(context) && !context_copied(iommu, bus, devfn))
 		goto out_unlock;
 
-	/*
-	 * For kdump cases, old valid entries may be cached due to the
-	 * in-flight DMA and copied pgtable, but there is no unmapping
-	 * behaviour for them, thus we need an explicit cache flush for
-	 * the newly-mapped device. For kdump, at this point, the device
-	 * is supposed to finish reset at its driver probe stage, so no
-	 * in-flight DMA will exist, and we don't need to worry anymore
-	 * hereafter.
-	 */
-	if (context_copied(iommu, bus, devfn)) {
-		u16 did_old = context_domain_id(context);
-
-		if (did_old < cap_ndoms(iommu->cap)) {
-			iommu->flush.flush_context(iommu, did_old,
-						   (((u16)bus) << 8) | devfn,
-						   DMA_CCMD_MASK_NOBIT,
-						   DMA_CCMD_DEVICE_INVL);
-			iommu->flush.flush_iotlb(iommu, did_old, 0, 0,
-						 DMA_TLB_DSI_FLUSH);
-		}
-
-		clear_context_copied(iommu, bus, devfn);
-	}
-
+	copied_context_tear_down(iommu, context, bus, devfn);
 	context_clear_entry(context);
+
 	context_set_domain_id(context, did);
 
 	if (translation != CONTEXT_TT_PASS_THROUGH) {
@@ -1685,23 +1718,7 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
 	context_set_present(context);
 	if (!ecap_coherent(iommu->ecap))
 		clflush_cache_range(context, sizeof(*context));
-
-	/*
-	 * It's a non-present to present mapping. If hardware doesn't cache
-	 * non-present entry we only need to flush the write-buffer. If the
-	 * _does_ cache non-present entries, then it does so in the special
-	 * domain #0, which we have to flush:
-	 */
-	if (cap_caching_mode(iommu->cap)) {
-		iommu->flush.flush_context(iommu, 0,
-					   (((u16)bus) << 8) | devfn,
-					   DMA_CCMD_MASK_NOBIT,
-					   DMA_CCMD_DEVICE_INVL);
-		iommu->flush.flush_iotlb(iommu, did, 0, 0, DMA_TLB_DSI_FLUSH);
-	} else {
-		iommu_flush_write_buffer(iommu);
-	}
-
+	context_present_cache_flush(iommu, did, bus, devfn);
 	ret = 0;
 
 out_unlock: