iommu/vt-d: Remove has_iotlb_device flag

The has_iotlb_device flag was used to indicate if a domain had attached
devices with ATS enabled. Domains without this flag didn't require device
TLB invalidation during unmap operations, optimizing performance by
avoiding unnecessary device iteration.

With the introduction of cache tags, this flag is no longer needed. The
code to iterate over attached devices was removed by commit 06792d0
("iommu/vt-d: Cleanup use of iommu_flush_iotlb_psi()").

Remove has_iotlb_device to avoid unnecessary code.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20240809055431.36513-5-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel/iommu.c

@@ -485,7 +485,6 @@ void domain_update_iommu_cap(struct dmar_domain *domain)
 		domain->domain.geometry.aperture_end = __DOMAIN_MAX_ADDR(domain->gaw);
 
 	domain->domain.pgsize_bitmap |= domain_super_pgsize_bitmap(domain);
-	domain_update_iotlb(domain);
 }
 
 struct context_entry *iommu_context_addr(struct intel_iommu *iommu, u8 bus,
@@ -1263,32 +1262,6 @@ domain_lookup_dev_info(struct dmar_domain *domain,
 	return NULL;
 }
 
-void domain_update_iotlb(struct dmar_domain *domain)
-{
-	struct dev_pasid_info *dev_pasid;
-	struct device_domain_info *info;
-	bool has_iotlb_device = false;
-	unsigned long flags;
-
-	spin_lock_irqsave(&domain->lock, flags);
-	list_for_each_entry(info, &domain->devices, link) {
-		if (info->ats_enabled) {
-			has_iotlb_device = true;
-			break;
-		}
-	}
-
-	list_for_each_entry(dev_pasid, &domain->dev_pasids, link_domain) {
-		info = dev_iommu_priv_get(dev_pasid->dev);
-		if (info->ats_enabled) {
-			has_iotlb_device = true;
-			break;
-		}
-	}
-	domain->has_iotlb_device = has_iotlb_device;
-	spin_unlock_irqrestore(&domain->lock, flags);
-}
-
 /*
  * The extra devTLB flush quirk impacts those QAT devices with PCI device
  * IDs ranging from 0x4940 to 0x4943. It is exempted from risky_device()
@@ -1325,10 +1298,8 @@ static void iommu_enable_pci_caps(struct device_domain_info *info)
 		info->pasid_enabled = 1;
 
 	if (info->ats_supported && pci_ats_page_aligned(pdev) &&
-	    !pci_enable_ats(pdev, VTD_PAGE_SHIFT)) {
+	    !pci_enable_ats(pdev, VTD_PAGE_SHIFT))
 		info->ats_enabled = 1;
-		domain_update_iotlb(info->domain);
-	}
 }
 
 static void iommu_disable_pci_caps(struct device_domain_info *info)
@@ -1343,7 +1314,6 @@ static void iommu_disable_pci_caps(struct device_domain_info *info)
 	if (info->ats_enabled) {
 		pci_disable_ats(pdev);
 		info->ats_enabled = 0;
-		domain_update_iotlb(info->domain);
 	}
 
 	if (info->pasid_enabled) {
@@ -1517,7 +1487,6 @@ static struct dmar_domain *alloc_domain(unsigned int type)
 	domain->nid = NUMA_NO_NODE;
 	if (first_level_by_default(type))
 		domain->use_first_level = true;
-	domain->has_iotlb_device = false;
 	INIT_LIST_HEAD(&domain->devices);
 	INIT_LIST_HEAD(&domain->dev_pasids);
 	INIT_LIST_HEAD(&domain->cache_tags);
@@ -3518,7 +3487,6 @@ static struct dmar_domain *paging_domain_alloc(struct device *dev, bool first_st
 	xa_init(&domain->iommu_array);
 
 	domain->nid = dev_to_node(dev);
-	domain->has_iotlb_device = info->ats_enabled;
 	domain->use_first_level = first_stage;
 
 	/* calculate the address width */

drivers/iommu/intel/iommu.h

@@ -588,7 +588,6 @@ struct dmar_domain {
 	int	nid;			/* node id */
 	struct xarray iommu_array;	/* Attached IOMMU array */
 
-	u8 has_iotlb_device: 1;
 	u8 iommu_coherency: 1;		/* indicate coherency of iommu access */
 	u8 force_snooping : 1;		/* Create IOPTEs with snoop control */
 	u8 set_pte_snp:1;
@@ -1104,7 +1103,6 @@ int qi_submit_sync(struct intel_iommu *iommu, struct qi_desc *desc,
  */
 #define QI_OPT_WAIT_DRAIN		BIT(0)
 
-void domain_update_iotlb(struct dmar_domain *domain);
 int domain_attach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu);
 void domain_detach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu);
 void device_block_translation(struct device *dev);

drivers/iommu/intel/nested.c

@@ -66,8 +66,6 @@ static int intel_nested_attach_dev(struct iommu_domain *domain,
 	list_add(&info->link, &dmar_domain->devices);
 	spin_unlock_irqrestore(&dmar_domain->lock, flags);
 
-	domain_update_iotlb(dmar_domain);
-
 	return 0;
 unassign_tag:
 	cache_tag_unassign_domain(dmar_domain, dev, IOMMU_NO_PASID);