iommu/vt-d: Unify domain->iommu attach/detachment

Move the code to attach/detach domains to iommus and vice
verce into a single function to make sure there are no
dangling references.

Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 49 insertions, 76 deletions

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 46359bd9da63..1cb7a3eb29d3 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1678,90 +1678,64 @@ static struct dmar_domain *alloc_domain(int flags)
         return domain;
 }
 
-static int __iommu_attach_domain(struct dmar_domain *domain,
-                                 struct intel_iommu *iommu)
-{
-        int num;
-        unsigned long ndomains;
-
-        num = domain->iommu_did[iommu->seq_id];
-        if (num)
-                return num;
-
-        ndomains = cap_ndoms(iommu->cap);
-        num      = find_first_zero_bit(iommu->domain_ids, ndomains);
-
-        if (num < ndomains) {
-                set_bit(num, iommu->domain_ids);
-                set_iommu_domain(iommu, num, domain);
-                domain->iommu_did[iommu->seq_id] = num;
-        } else {
-                num = -ENOSPC;
-        }
-
-        if (num < 0)
-                pr_err("%s: No free domain ids\n", iommu->name);
-
-        return num;
-}
-
-static int iommu_attach_domain(struct dmar_domain *domain,
+/* Must be called with iommu->lock */
+static int domain_attach_iommu(struct dmar_domain *domain,
                                struct intel_iommu *iommu)
 {
-        int num;
-        unsigned long flags;
-
-        spin_lock_irqsave(&iommu->lock, flags);
-        num = __iommu_attach_domain(domain, iommu);
-        spin_unlock_irqrestore(&iommu->lock, flags);
-
-        return num;
-}
-
-static void iommu_detach_domain(struct dmar_domain *domain,
-                                struct intel_iommu *iommu)
-{
+        unsigned long ndomains;
         unsigned long flags;
-        int num;
-
-        spin_lock_irqsave(&iommu->lock, flags);
+        int ret, num;
 
-        num = domain->iommu_did[iommu->seq_id];
-
-        if (num == 0)
-                return;
-
-        clear_bit(num, iommu->domain_ids);
-        set_iommu_domain(iommu, num, NULL);
-
-        spin_unlock_irqrestore(&iommu->lock, flags);
-}
-
-static void domain_attach_iommu(struct dmar_domain *domain,
-                               struct intel_iommu *iommu)
-{
-        unsigned long flags;
+        assert_spin_locked(&iommu->lock);
 
         spin_lock_irqsave(&domain->iommu_lock, flags);
+
         domain->iommu_refcnt[iommu->seq_id] += 1;
         domain->iommu_count += 1;
         if (domain->iommu_refcnt[iommu->seq_id] == 1) {
-                domain->nid = iommu->node;
+                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;
+                        domain->iommu_count -= 1;
+                        ret = -ENOSPC;
+                        goto out_unlock;
+                }
+
+                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);
         }
+
+        ret = 0;
+out_unlock:
         spin_unlock_irqrestore(&domain->iommu_lock, flags);
+
+        return ret;
 }
 
 static int domain_detach_iommu(struct dmar_domain *domain,
                                struct intel_iommu *iommu)
 {
+        int num, count = INT_MAX;
         unsigned long flags;
-        int count = INT_MAX;
+
+        assert_spin_locked(&iommu->lock);
 
         spin_lock_irqsave(&domain->iommu_lock, flags);
         domain->iommu_refcnt[iommu->seq_id] -= 1;
         count = --domain->iommu_count;
         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;
         }
@@ -1886,7 +1860,6 @@ static int domain_init(struct dmar_domain *domain, struct intel_iommu *iommu,
 static void domain_exit(struct dmar_domain *domain)
 {
         struct page *freelist = NULL;
-        int i;
 
         /* Domain 0 is reserved, so dont process it */
         if (!domain)
@@ -1896,20 +1869,16 @@ static void domain_exit(struct dmar_domain *domain)
         if (!intel_iommu_strict)
                 flush_unmaps_timeout(0);
 
-        /* remove associated devices */
+        /* Remove associated devices and clear attached or cached domains */
+        rcu_read_lock();
         domain_remove_dev_info(domain);
+        rcu_read_unlock();
 
         /* destroy iovas */
         put_iova_domain(&domain->iovad);
 
         freelist = domain_unmap(domain, 0, DOMAIN_MAX_PFN(domain->gaw));
 
-        /* clear attached or cached domains */
-        rcu_read_lock();
-        for_each_domain_iommu(i, domain)
-                iommu_detach_domain(domain, g_iommus[i]);
-        rcu_read_unlock();
-
         dma_free_pagelist(freelist);
 
         free_domain_mem(domain);
@@ -2286,6 +2255,7 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
         struct dmar_domain *found = NULL;
         struct device_domain_info *info;
         unsigned long flags;
+        int ret;
 
         info = alloc_devinfo_mem();
         if (!info)
@@ -2313,11 +2283,14 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
                 return found;
         }
 
-        if (iommu_attach_domain(domain, iommu) < 0) {
+        spin_lock(&iommu->lock);
+        ret = domain_attach_iommu(domain, iommu);
+        spin_unlock(&iommu->lock);
+
+        if (ret) {
                 spin_unlock_irqrestore(&device_domain_lock, flags);
                 return NULL;
         }
-        domain_attach_iommu(domain, iommu);
 
         list_add(&info->link, &domain->devices);
         list_add(&info->global, &device_domain_list);
@@ -4590,12 +4563,10 @@ static void dmar_remove_one_dev_info(struct dmar_domain *domain,
         iommu_disable_dev_iotlb(info);
         domain_context_clear(iommu, dev);
         free_devinfo_mem(info);
-        domain_detach_iommu(domain, iommu);
 
-        spin_lock_irqsave(&domain->iommu_lock, flags);
-        if (!domain->iommu_refcnt[iommu->seq_id])
-                iommu_detach_domain(domain, iommu);
-        spin_unlock_irqrestore(&domain->iommu_lock, flags);
+        spin_lock_irqsave(&iommu->lock, flags);
+        domain_detach_iommu(domain, iommu);
+        spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
 static int md_domain_init(struct dmar_domain *domain, int guest_width)
@@ -4676,10 +4647,12 @@ static int intel_iommu_attach_device(struct iommu_domain *domain,
 
                 old_domain = find_domain(dev);
                 if (old_domain) {
+                        rcu_read_lock();
                         if (domain_type_is_vm_or_si(dmar_domain))
                                 dmar_remove_one_dev_info(old_domain, dev);
                         else
                                 domain_remove_dev_info(old_domain);
+                        rcu_read_unlock();
 
                         if (!domain_type_is_vm_or_si(old_domain) &&
                              list_empty(&old_domain->devices))