iommu/vt-d: Remove intel_iommu::domains

The "domains" field of the intel_iommu structure keeps the mapping of
domain_id to dmar_domain. This information is not used anywhere. Remove
and cleanup it to avoid unnecessary memory consumption.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20220214025704.3184654-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20220301020159.633356-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: LuBaolu

drivers/iommu/intel/iommu.c

@@ -455,36 +455,6 @@ __setup("intel_iommu=", intel_iommu_setup);
 static struct kmem_cache *iommu_domain_cache;
 static struct kmem_cache *iommu_devinfo_cache;
 
-static struct dmar_domain* get_iommu_domain(struct intel_iommu *iommu, u16 did)
-{
-	struct dmar_domain **domains;
-	int idx = did >> 8;
-
-	domains = iommu->domains[idx];
-	if (!domains)
-		return NULL;
-
-	return domains[did & 0xff];
-}
-
-static void set_iommu_domain(struct intel_iommu *iommu, u16 did,
-			     struct dmar_domain *domain)
-{
-	struct dmar_domain **domains;
-	int idx = did >> 8;
-
-	if (!iommu->domains[idx]) {
-		size_t size = 256 * sizeof(struct dmar_domain *);
-		iommu->domains[idx] = kzalloc(size, GFP_ATOMIC);
-	}
-
-	domains = iommu->domains[idx];
-	if (WARN_ON(!domains))
-		return;
-	else
-		domains[did & 0xff] = domain;
-}
-
 void *alloc_pgtable_page(int node)
 {
 	struct page *page;
@@ -1751,8 +1721,7 @@ static void intel_flush_iotlb_all(struct iommu_domain *domain)
 						 DMA_TLB_DSI_FLUSH);
 
 		if (!cap_caching_mode(iommu->cap))
-			iommu_flush_dev_iotlb(get_iommu_domain(iommu, did),
-					      0, MAX_AGAW_PFN_WIDTH);
+			iommu_flush_dev_iotlb(dmar_domain, 0, MAX_AGAW_PFN_WIDTH);
 	}
 }
 
@@ -1815,7 +1784,6 @@ static void iommu_disable_translation(struct intel_iommu *iommu)
 static int iommu_init_domains(struct intel_iommu *iommu)
 {
 	u32 ndomains;
-	size_t size;
 
 	ndomains = cap_ndoms(iommu->cap);
 	pr_debug("%s: Number of Domains supported <%d>\n",
@@ -1827,24 +1795,6 @@ static int iommu_init_domains(struct intel_iommu *iommu)
 	if (!iommu->domain_ids)
 		return -ENOMEM;
 
-	size = (ALIGN(ndomains, 256) >> 8) * sizeof(struct dmar_domain **);
-	iommu->domains = kzalloc(size, GFP_KERNEL);
-
-	if (iommu->domains) {
-		size = 256 * sizeof(struct dmar_domain *);
-		iommu->domains[0] = kzalloc(size, GFP_KERNEL);
-	}
-
-	if (!iommu->domains || !iommu->domains[0]) {
-		pr_err("%s: Allocating domain array failed\n",
-		       iommu->name);
-		bitmap_free(iommu->domain_ids);
-		kfree(iommu->domains);
-		iommu->domain_ids = NULL;
-		iommu->domains    = NULL;
-		return -ENOMEM;
-	}
-
 	/*
 	 * If Caching mode is set, then invalid translations are tagged
 	 * with domain-id 0, hence we need to pre-allocate it. We also
@@ -1871,7 +1821,7 @@ static void disable_dmar_iommu(struct intel_iommu *iommu)
 	struct device_domain_info *info, *tmp;
 	unsigned long flags;
 
-	if (!iommu->domains || !iommu->domain_ids)
+	if (!iommu->domain_ids)
 		return;
 
 	spin_lock_irqsave(&device_domain_lock, flags);
@@ -1892,15 +1842,8 @@ static void disable_dmar_iommu(struct intel_iommu *iommu)
 
 static void free_dmar_iommu(struct intel_iommu *iommu)
 {
-	if ((iommu->domains) && (iommu->domain_ids)) {
-		int elems = ALIGN(cap_ndoms(iommu->cap), 256) >> 8;
-		int i;
-
-		for (i = 0; i < elems; i++)
-			kfree(iommu->domains[i]);
-		kfree(iommu->domains);
+	if (iommu->domain_ids) {
 		bitmap_free(iommu->domain_ids);
-		iommu->domains = NULL;
 		iommu->domain_ids = NULL;
 	}
 
@@ -1978,11 +1921,8 @@ static int domain_attach_iommu(struct dmar_domain *domain,
 		}
 
 		set_bit(num, iommu->domain_ids);
-		set_iommu_domain(iommu, num, domain);
-
 		domain->iommu_did[iommu->seq_id] = num;
 		domain->nid			 = iommu->node;
-
 		domain_update_iommu_cap(domain);
 	}
 
@@ -2001,8 +1941,6 @@ static void domain_detach_iommu(struct dmar_domain *domain,
 	if (domain->iommu_refcnt[iommu->seq_id] == 0) {
 		num = domain->iommu_did[iommu->seq_id];
 		clear_bit(num, iommu->domain_ids);
-		set_iommu_domain(iommu, num, NULL);
-
 		domain_update_iommu_cap(domain);
 		domain->iommu_did[iommu->seq_id] = 0;
 	}

include/linux/intel-iommu.h

@@ -578,7 +578,6 @@ struct intel_iommu {
 
 #ifdef CONFIG_INTEL_IOMMU
 	unsigned long 	*domain_ids; /* bitmap of domains */
-	struct dmar_domain ***domains; /* ptr to domains */
 	spinlock_t	lock; /* protect context, domain ids */
 	struct root_entry *root_entry; /* virtual address */