iommu/vt-d: Refactor iommu information of each domain

When a DMA domain is attached to a device, it needs to allocate a domain
ID from its IOMMU. Currently, the domain ID information is stored in two
static arrays embedded in the domain structure. This can lead to memory
waste when the driver is running on a small platform.

This optimizes these static arrays by replacing them with an xarray and
consuming memory on demand.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lore.kernel.org/r/20220702015610.2849494-4-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: LuBaolu

drivers/iommu/intel/iommu.c

@@ -254,10 +254,6 @@ static inline void context_clear_entry(struct context_entry *context)
 static struct dmar_domain *si_domain;
 static int hw_pass_through = 1;
 
-#define for_each_domain_iommu(idx, domain)			\
-	for (idx = 0; idx < g_num_of_iommus; idx++)		\
-		if (domain->iommu_refcnt[idx])
-
 struct dmar_rmrr_unit {
 	struct list_head list;		/* list of rmrr units	*/
 	struct acpi_dmar_header *hdr;	/* ACPI header		*/
@@ -453,16 +449,16 @@ static inline bool iommu_paging_structure_coherency(struct intel_iommu *iommu)
 
 static void domain_update_iommu_coherency(struct dmar_domain *domain)
 {
+	struct iommu_domain_info *info;
 	struct dmar_drhd_unit *drhd;
 	struct intel_iommu *iommu;
 	bool found = false;
-	int i;
+	unsigned long i;
 
 	domain->iommu_coherency = true;
-
-	for_each_domain_iommu(i, domain) {
+	xa_for_each(&domain->iommu_array, i, info) {
 		found = true;
-		if (!iommu_paging_structure_coherency(g_iommus[i])) {
+		if (!iommu_paging_structure_coherency(info->iommu)) {
 			domain->iommu_coherency = false;
 			break;
 		}
@@ -1495,7 +1491,7 @@ static void iommu_flush_iotlb_psi(struct intel_iommu *iommu,
 	unsigned int aligned_pages = __roundup_pow_of_two(pages);
 	unsigned int mask = ilog2(aligned_pages);
 	uint64_t addr = (uint64_t)pfn << VTD_PAGE_SHIFT;
-	u16 did = domain->iommu_did[iommu->seq_id];
+	u16 did = domain_id_iommu(domain, iommu);
 
 	BUG_ON(pages == 0);
 
@@ -1565,11 +1561,12 @@ static inline void __mapping_notify_one(struct intel_iommu *iommu,
 static void intel_flush_iotlb_all(struct iommu_domain *domain)
 {
 	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
-	int idx;
+	struct iommu_domain_info *info;
+	unsigned long idx;
 
-	for_each_domain_iommu(idx, dmar_domain) {
-		struct intel_iommu *iommu = g_iommus[idx];
-		u16 did = dmar_domain->iommu_did[iommu->seq_id];
+	xa_for_each(&dmar_domain->iommu_array, idx, info) {
+		struct intel_iommu *iommu = info->iommu;
+		u16 did = domain_id_iommu(dmar_domain, iommu);
 
 		if (domain_use_first_level(dmar_domain))
 			qi_flush_piotlb(iommu, did, PASID_RID2PASID, 0, -1, 0);
@@ -1745,52 +1742,74 @@ static struct dmar_domain *alloc_domain(unsigned int type)
 	domain->has_iotlb_device = false;
 	INIT_LIST_HEAD(&domain->devices);
 	spin_lock_init(&domain->lock);
+	xa_init(&domain->iommu_array);
 
 	return domain;
 }
 
 static int domain_attach_iommu(struct dmar_domain *domain,
 			       struct intel_iommu *iommu)
 {
+	struct iommu_domain_info *info, *curr;
 	unsigned long ndomains;
-	int num, ret = 0;
+	int num, ret = -ENOSPC;
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
 
 	spin_lock(&iommu->lock);
-	domain->iommu_refcnt[iommu->seq_id] += 1;
-	if (domain->iommu_refcnt[iommu->seq_id] == 1) {
-		ndomains = cap_ndoms(iommu->cap);
-		num      = find_first_zero_bit(iommu->domain_ids, ndomains);
-
-		if (num >= ndomains) {
-			pr_err("%s: No free domain ids\n", iommu->name);
-			domain->iommu_refcnt[iommu->seq_id] -= 1;
-			ret = -ENOSPC;
-			goto out_unlock;
-		}
+	curr = xa_load(&domain->iommu_array, iommu->seq_id);
+	if (curr) {
+		curr->refcnt++;
+		spin_unlock(&iommu->lock);
+		kfree(info);
+		return 0;
+	}
 
-		set_bit(num, iommu->domain_ids);
-		domain->iommu_did[iommu->seq_id] = num;
-		domain->nid			 = iommu->node;
-		domain_update_iommu_cap(domain);
+	ndomains = cap_ndoms(iommu->cap);
+	num = find_first_zero_bit(iommu->domain_ids, ndomains);
+	if (num >= ndomains) {
+		pr_err("%s: No free domain ids\n", iommu->name);
+		goto err_unlock;
 	}
 
-out_unlock:
+	set_bit(num, iommu->domain_ids);
+	info->refcnt	= 1;
+	info->did	= num;
+	info->iommu	= iommu;
+	curr = xa_cmpxchg(&domain->iommu_array, iommu->seq_id,
+			  NULL, info, GFP_ATOMIC);
+	if (curr) {
+		ret = xa_err(curr) ? : -EBUSY;
+		goto err_clear;
+	}
+	domain_update_iommu_cap(domain);
+
 	spin_unlock(&iommu->lock);
+	return 0;
+
+err_clear:
+	clear_bit(info->did, iommu->domain_ids);
+err_unlock:
+	spin_unlock(&iommu->lock);
+	kfree(info);
 	return ret;
 }
 
 static void domain_detach_iommu(struct dmar_domain *domain,
 				struct intel_iommu *iommu)
 {
-	int num;
+	struct iommu_domain_info *info;
 
 	spin_lock(&iommu->lock);
-	domain->iommu_refcnt[iommu->seq_id] -= 1;
-	if (domain->iommu_refcnt[iommu->seq_id] == 0) {
-		num = domain->iommu_did[iommu->seq_id];
-		clear_bit(num, iommu->domain_ids);
+	info = xa_load(&domain->iommu_array, iommu->seq_id);
+	if (--info->refcnt == 0) {
+		clear_bit(info->did, iommu->domain_ids);
+		xa_erase(&domain->iommu_array, iommu->seq_id);
+		domain->nid = NUMA_NO_NODE;
 		domain_update_iommu_cap(domain);
-		domain->iommu_did[iommu->seq_id] = 0;
+		kfree(info);
 	}
 	spin_unlock(&iommu->lock);
 }
@@ -1880,7 +1899,7 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
 {
 	struct device_domain_info *info =
 			iommu_support_dev_iotlb(domain, iommu, bus, devfn);
-	u16 did = domain->iommu_did[iommu->seq_id];
+	u16 did = domain_id_iommu(domain, iommu);
 	int translation = CONTEXT_TT_MULTI_LEVEL;
 	struct context_entry *context;
 	int ret;
@@ -2129,8 +2148,9 @@ static void switch_to_super_page(struct dmar_domain *domain,
 				 unsigned long end_pfn, int level)
 {
 	unsigned long lvl_pages = lvl_to_nr_pages(level);
+	struct iommu_domain_info *info;
 	struct dma_pte *pte = NULL;
-	int i;
+	unsigned long i;
 
 	while (start_pfn <= end_pfn) {
 		if (!pte)
@@ -2141,8 +2161,8 @@ static void switch_to_super_page(struct dmar_domain *domain,
 					       start_pfn + lvl_pages - 1,
 					       level + 1);
 
-			for_each_domain_iommu(i, domain)
-				iommu_flush_iotlb_psi(g_iommus[i], domain,
+			xa_for_each(&domain->iommu_array, i, info)
+				iommu_flush_iotlb_psi(info->iommu, domain,
 						      start_pfn, lvl_pages,
 						      0, 0);
 		}
@@ -2272,7 +2292,7 @@ static void domain_context_clear_one(struct device_domain_info *info, u8 bus, u8
 		if (hw_pass_through && domain_type_is_si(info->domain))
 			did_old = FLPT_DEFAULT_DID;
 		else
-			did_old = info->domain->iommu_did[iommu->seq_id];
+			did_old = domain_id_iommu(info->domain, iommu);
 	} else {
 		did_old = context_domain_id(context);
 	}
@@ -2330,7 +2350,7 @@ static int domain_setup_first_level(struct intel_iommu *iommu,
 		flags |= PASID_FLAG_PAGE_SNOOP;
 
 	return intel_pasid_setup_first_level(iommu, dev, (pgd_t *)pgd, pasid,
-					     domain->iommu_did[iommu->seq_id],
+					     domain_id_iommu(domain, iommu),
 					     flags);
 }
 
@@ -4368,15 +4388,16 @@ static void intel_iommu_tlb_sync(struct iommu_domain *domain,
 	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
 	unsigned long iova_pfn = IOVA_PFN(gather->start);
 	size_t size = gather->end - gather->start;
+	struct iommu_domain_info *info;
 	unsigned long start_pfn;
 	unsigned long nrpages;
-	int iommu_id;
+	unsigned long i;
 
 	nrpages = aligned_nrpages(gather->start, size);
 	start_pfn = mm_to_dma_pfn(iova_pfn);
 
-	for_each_domain_iommu(iommu_id, dmar_domain)
-		iommu_flush_iotlb_psi(g_iommus[iommu_id], dmar_domain,
+	xa_for_each(&dmar_domain->iommu_array, i, info)
+		iommu_flush_iotlb_psi(info->iommu, dmar_domain,
 				      start_pfn, nrpages,
 				      list_empty(&gather->freelist), 0);
 
@@ -4620,7 +4641,7 @@ int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct device *dev)
 		context[0].lo = ctx_lo;
 		wmb();
 		iommu->flush.flush_context(iommu,
-					   domain->iommu_did[iommu->seq_id],
+					   domain_id_iommu(domain, iommu),
 					   PCI_DEVID(info->bus, info->devfn),
 					   DMA_CCMD_MASK_NOBIT,
 					   DMA_CCMD_DEVICE_INVL);
@@ -4757,13 +4778,11 @@ static void intel_iommu_iotlb_sync_map(struct iommu_domain *domain,
 	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
 	unsigned long pages = aligned_nrpages(iova, size);
 	unsigned long pfn = iova >> VTD_PAGE_SHIFT;
-	struct intel_iommu *iommu;
-	int iommu_id;
+	struct iommu_domain_info *info;
+	unsigned long i;
 
-	for_each_domain_iommu(iommu_id, dmar_domain) {
-		iommu = g_iommus[iommu_id];
-		__mapping_notify_one(iommu, dmar_domain, pfn, pages);
-	}
+	xa_for_each(&dmar_domain->iommu_array, i, info)
+		__mapping_notify_one(info->iommu, dmar_domain, pfn, pages);
 }
 
 const struct iommu_ops intel_iommu_ops = {

drivers/iommu/intel/iommu.h

@@ -21,6 +21,7 @@
 #include <linux/dmar.h>
 #include <linux/ioasid.h>
 #include <linux/bitfield.h>
+#include <linux/xarray.h>
 
 #include <asm/cacheflush.h>
 #include <asm/iommu.h>
@@ -524,17 +525,17 @@ struct context_entry {
  */
 #define DOMAIN_FLAG_USE_FIRST_LEVEL		BIT(1)
 
-struct dmar_domain {
-	int	nid;			/* node id */
-
-	unsigned int iommu_refcnt[DMAR_UNITS_SUPPORTED];
-					/* Refcount of devices per iommu */
-
-
-	u16		iommu_did[DMAR_UNITS_SUPPORTED];
-					/* Domain ids per IOMMU. Use u16 since
+struct iommu_domain_info {
+	struct intel_iommu *iommu;
+	unsigned int refcnt;		/* Refcount of devices per iommu */
+	u16 did;			/* Domain ids per IOMMU. Use u16 since
 					 * domain ids are 16 bit wide according
 					 * to VT-d spec, section 9.3 */
+};
+
+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 */
@@ -640,6 +641,16 @@ static inline struct dmar_domain *to_dmar_domain(struct iommu_domain *dom)
 	return container_of(dom, struct dmar_domain, domain);
 }
 
+/* Retrieve the domain ID which has allocated to the domain */
+static inline u16
+domain_id_iommu(struct dmar_domain *domain, struct intel_iommu *iommu)
+{
+	struct iommu_domain_info *info =
+			xa_load(&domain->iommu_array, iommu->seq_id);
+
+	return info->did;
+}
+
 /*
  * 0: readable
  * 1: writable

drivers/iommu/intel/pasid.c

@@ -626,7 +626,7 @@ int intel_pasid_setup_second_level(struct intel_iommu *iommu,
 	}
 
 	pgd_val = virt_to_phys(pgd);
-	did = domain->iommu_did[iommu->seq_id];
+	did = domain_id_iommu(domain, iommu);
 
 	spin_lock(&iommu->lock);
 	pte = intel_pasid_get_entry(dev, pasid);

drivers/iommu/intel/svm.c

@@ -541,7 +541,7 @@ static void intel_svm_drain_prq(struct device *dev, u32 pasid)
 	domain = info->domain;
 	pdev = to_pci_dev(dev);
 	sid = PCI_DEVID(info->bus, info->devfn);
-	did = domain->iommu_did[iommu->seq_id];
+	did = domain_id_iommu(domain, iommu);
 	qdep = pci_ats_queue_depth(pdev);
 
 	/*