[PATCH v4 2/7] iommu/vt-d: Remove identity mappings from si_domain

[Lu Baolu <baolu.lu@linux.intel.com>]

As the driver has enforced DMA domains for devices managed by an IOMMU
hardware that doesn't support passthrough translation mode, there is no
need for static identity mappings in the si_domain. Remove the identity
mapping code to avoid dead code.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 122 ++----------------------------------
 1 file changed, 4 insertions(+), 118 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 90ad794a1be7..723ea9f3f501 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -167,14 +167,7 @@ static void device_rbtree_remove(struct device_domain_info *info)
 	spin_unlock_irqrestore(&iommu->device_rbtree_lock, flags);
 }
 
-/*
- * This domain is a statically identity mapping domain.
- *	1. This domain creats a static 1:1 mapping to all usable memory.
- * 	2. It maps to each iommu if successful.
- *	3. Each iommu mapps to this domain if successful.
- */
 static struct dmar_domain *si_domain;
-static int hw_pass_through = 1;
 
 struct dmar_rmrr_unit {
 	struct list_head list;		/* list of rmrr units	*/
@@ -1647,7 +1640,7 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
 	struct context_entry *context;
 	int agaw, ret;
 
-	if (hw_pass_through && domain_type_is_si(domain))
+	if (domain_type_is_si(domain))
 		translation = CONTEXT_TT_PASS_THROUGH;
 
 	pr_debug("Set context mapping for %02x:%02x.%d\n",
@@ -1998,29 +1991,10 @@ static bool dev_is_real_dma_subdevice(struct device *dev)
 	       pci_real_dma_dev(to_pci_dev(dev)) != to_pci_dev(dev);
 }
 
-static int iommu_domain_identity_map(struct dmar_domain *domain,
-				     unsigned long first_vpfn,
-				     unsigned long last_vpfn)
-{
-	/*
-	 * RMRR range might have overlap with physical memory range,
-	 * clear it first
-	 */
-	dma_pte_clear_range(domain, first_vpfn, last_vpfn);
-
-	return __domain_mapping(domain, first_vpfn,
-				first_vpfn, last_vpfn - first_vpfn + 1,
-				DMA_PTE_READ|DMA_PTE_WRITE, GFP_KERNEL);
-}
-
 static int md_domain_init(struct dmar_domain *domain, int guest_width);
 
-static int __init si_domain_init(int hw)
+static int __init si_domain_init(void)
 {
-	struct dmar_rmrr_unit *rmrr;
-	struct device *dev;
-	int i, nid, ret;
-
 	si_domain = alloc_domain(IOMMU_DOMAIN_IDENTITY);
 	if (!si_domain)
 		return -EFAULT;
@@ -2031,44 +2005,6 @@ static int __init si_domain_init(int hw)
 		return -EFAULT;
 	}
 
-	if (hw)
-		return 0;
-
-	for_each_online_node(nid) {
-		unsigned long start_pfn, end_pfn;
-		int i;
-
-		for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
-			ret = iommu_domain_identity_map(si_domain,
-					mm_to_dma_pfn_start(start_pfn),
-					mm_to_dma_pfn_end(end_pfn-1));
-			if (ret)
-				return ret;
-		}
-	}
-
-	/*
-	 * Identity map the RMRRs so that devices with RMRRs could also use
-	 * the si_domain.
-	 */
-	for_each_rmrr_units(rmrr) {
-		for_each_active_dev_scope(rmrr->devices, rmrr->devices_cnt,
-					  i, dev) {
-			unsigned long long start = rmrr->base_address;
-			unsigned long long end = rmrr->end_address;
-
-			if (WARN_ON(end < start ||
-				    end >> agaw_to_width(si_domain->agaw)))
-				continue;
-
-			ret = iommu_domain_identity_map(si_domain,
-					mm_to_dma_pfn_start(start >> PAGE_SHIFT),
-					mm_to_dma_pfn_end(end >> PAGE_SHIFT));
-			if (ret)
-				return ret;
-		}
-	}
-
 	return 0;
 }
 
@@ -2094,7 +2030,7 @@ static int dmar_domain_attach_device(struct dmar_domain *domain,
 
 	if (!sm_supported(iommu))
 		ret = domain_context_mapping(domain, dev);
-	else if (hw_pass_through && domain_type_is_si(domain))
+	else if (domain_type_is_si(domain))
 		ret = intel_pasid_setup_pass_through(iommu, dev, IOMMU_NO_PASID);
 	else if (domain->use_first_level)
 		ret = domain_setup_first_level(iommu, domain, dev, IOMMU_NO_PASID);
@@ -2449,8 +2385,6 @@ static int __init init_dmars(void)
 			}
 		}
 
-		if (!ecap_pass_through(iommu->ecap))
-			hw_pass_through = 0;
 		intel_svm_check(iommu);
 	}
 
@@ -2466,7 +2400,7 @@ static int __init init_dmars(void)
 
 	check_tylersburg_isoch();
 
-	ret = si_domain_init(hw_pass_through);
+	ret = si_domain_init();
 	if (ret)
 		goto free_iommu;
 
@@ -2893,12 +2827,6 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 	if (ret)
 		goto out;
 
-	if (hw_pass_through && !ecap_pass_through(iommu->ecap)) {
-		pr_warn("%s: Doesn't support hardware pass through.\n",
-			iommu->name);
-		return -ENXIO;
-	}
-
 	sp = domain_update_iommu_superpage(NULL, iommu) - 1;
 	if (sp >= 0 && !(cap_super_page_val(iommu->cap) & (1 << sp))) {
 		pr_warn("%s: Doesn't support large page.\n",
@@ -3149,43 +3077,6 @@ int dmar_iommu_notify_scope_dev(struct dmar_pci_notify_info *info)
 	return 0;
 }
 
-static int intel_iommu_memory_notifier(struct notifier_block *nb,
-				       unsigned long val, void *v)
-{
-	struct memory_notify *mhp = v;
-	unsigned long start_vpfn = mm_to_dma_pfn_start(mhp->start_pfn);
-	unsigned long last_vpfn = mm_to_dma_pfn_end(mhp->start_pfn +
-			mhp->nr_pages - 1);
-
-	switch (val) {
-	case MEM_GOING_ONLINE:
-		if (iommu_domain_identity_map(si_domain,
-					      start_vpfn, last_vpfn)) {
-			pr_warn("Failed to build identity map for [%lx-%lx]\n",
-				start_vpfn, last_vpfn);
-			return NOTIFY_BAD;
-		}
-		break;
-
-	case MEM_OFFLINE:
-	case MEM_CANCEL_ONLINE:
-		{
-			LIST_HEAD(freelist);
-
-			domain_unmap(si_domain, start_vpfn, last_vpfn, &freelist);
-			iommu_put_pages_list(&freelist);
-		}
-		break;
-	}
-
-	return NOTIFY_OK;
-}
-
-static struct notifier_block intel_iommu_memory_nb = {
-	.notifier_call = intel_iommu_memory_notifier,
-	.priority = 0
-};
-
 static void intel_disable_iommus(void)
 {
 	struct intel_iommu *iommu = NULL;
@@ -3482,12 +3373,7 @@ int __init intel_iommu_init(void)
 
 		iommu_pmu_register(iommu);
 	}
-	up_read(&dmar_global_lock);
 
-	if (si_domain && !hw_pass_through)
-		register_memory_notifier(&intel_iommu_memory_nb);
-
-	down_read(&dmar_global_lock);
 	if (probe_acpi_namespace_devices())
 		pr_warn("ACPI name space devices didn't probe correctly\n");
 
-- 
2.34.1