iommu/vt-d: Get rid of domain->iommu_lock

When this lock is held the device_domain_lock is also
required to make sure the device_domain_info does not vanish
while in use. So this lock can be removed as it gives no
additional protection.

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

1 files changed, 49 insertions, 38 deletions

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index c8d9bef776da..0f258f0f5ac0 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -406,7 +406,6 @@ struct dmar_domain {
         int             iommu_superpage;/* Level of superpages supported:
                                            0 == 4KiB (no superpages), 1 == 2MiB,
                                            2 == 1GiB, 3 == 512GiB, 4 == 1TiB */
-        spinlock_t      iommu_lock;     /* protect iommu set in domain */
         u64             max_addr;       /* maximum mapped address */
 
         struct iommu_domain domain;     /* generic domain data structure for
@@ -476,6 +475,8 @@ static void dmar_remove_one_dev_info(struct dmar_domain *domain,
                                      struct device *dev);
 static void domain_context_clear(struct intel_iommu *iommu,
                                  struct device *dev);
+static void __dmar_remove_one_dev_info(struct dmar_domain *domain,
+                                       struct device *dev);
 static int domain_detach_iommu(struct dmar_domain *domain,
                                struct intel_iommu *iommu);
 
@@ -1404,24 +1405,23 @@ iommu_support_dev_iotlb (struct dmar_domain *domain, struct intel_iommu *iommu,
                          u8 bus, u8 devfn)
 {
         bool found = false;
-        unsigned long flags;
         struct device_domain_info *info;
         struct pci_dev *pdev;
 
+        assert_spin_locked(&device_domain_lock);
+
         if (!ecap_dev_iotlb_support(iommu->ecap))
                 return NULL;
 
         if (!iommu->qi)
                 return NULL;
 
-        spin_lock_irqsave(&device_domain_lock, flags);
         list_for_each_entry(info, &domain->devices, link)
                 if (info->iommu == iommu && info->bus == bus &&
                     info->devfn == devfn) {
                         found = true;
                         break;
                 }
-        spin_unlock_irqrestore(&device_domain_lock, flags);
 
         if (!found || !info->dev || !dev_is_pci(info->dev))
                 return NULL;
@@ -1616,10 +1616,12 @@ static int iommu_init_domains(struct intel_iommu *iommu)
 static void disable_dmar_iommu(struct intel_iommu *iommu)
 {
         struct device_domain_info *info, *tmp;
+        unsigned long flags;
 
         if (!iommu->domains || !iommu->domain_ids)
                 return;
 
+        spin_lock_irqsave(&device_domain_lock, flags);
         list_for_each_entry_safe(info, tmp, &device_domain_list, global) {
                 struct dmar_domain *domain;
 
@@ -1636,6 +1638,7 @@ static void disable_dmar_iommu(struct intel_iommu *iommu)
                 if (!domain_type_is_vm_or_si(domain))
                         domain_exit(domain);
         }
+        spin_unlock_irqrestore(&device_domain_lock, flags);
 
         if (iommu->gcmd & DMA_GCMD_TE)
                 iommu_disable_translation(iommu);
@@ -1672,7 +1675,6 @@ static struct dmar_domain *alloc_domain(int flags)
         memset(domain, 0, sizeof(*domain));
         domain->nid = -1;
         domain->flags = flags;
-        spin_lock_init(&domain->iommu_lock);
         INIT_LIST_HEAD(&domain->devices);
 
         return domain;
@@ -1683,13 +1685,11 @@ static int domain_attach_iommu(struct dmar_domain *domain,
                                struct intel_iommu *iommu)
 {
         unsigned long ndomains;
-        unsigned long flags;
-        int ret, num;
+        int num;
 
+        assert_spin_locked(&device_domain_lock);
         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) {
@@ -1700,8 +1700,7 @@ static int domain_attach_iommu(struct dmar_domain *domain,
                         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;
+                        return -ENOSPC;
                 }
 
                 set_bit(num, iommu->domain_ids);
@@ -1713,22 +1712,17 @@ static int domain_attach_iommu(struct dmar_domain *domain,
                 domain_update_iommu_cap(domain);
         }
 
-        ret = 0;
-out_unlock:
-        spin_unlock_irqrestore(&domain->iommu_lock, flags);
-
-        return ret;
+        return 0;
 }
 
 static int domain_detach_iommu(struct dmar_domain *domain,
                                struct intel_iommu *iommu)
 {
         int num, count = INT_MAX;
-        unsigned long flags;
 
+        assert_spin_locked(&device_domain_lock);
         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) {
@@ -1739,7 +1733,6 @@ static int domain_detach_iommu(struct dmar_domain *domain,
                 domain_update_iommu_cap(domain);
                 domain->iommu_did[iommu->seq_id] = 0;
         }
-        spin_unlock_irqrestore(&domain->iommu_lock, flags);
 
         return count;
 }
@@ -1894,7 +1887,7 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
         struct context_entry *context;
         unsigned long flags;
         struct dma_pte *pgd;
-        int agaw;
+        int ret, agaw;
 
         WARN_ON(did == 0);
 
@@ -1906,16 +1899,17 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
 
         BUG_ON(!domain->pgd);
 
-        spin_lock_irqsave(&iommu->lock, flags);
+        spin_lock_irqsave(&device_domain_lock, flags);
+        spin_lock(&iommu->lock);
+
+        ret = -ENOMEM;
         context = iommu_context_addr(iommu, bus, devfn, 1);
-        spin_unlock_irqrestore(&iommu->lock, flags);
         if (!context)
-                return -ENOMEM;
-        spin_lock_irqsave(&iommu->lock, flags);
-        if (context_present(context)) {
-                spin_unlock_irqrestore(&iommu->lock, flags);
-                return 0;
-        }
+                goto out_unlock;
+
+        ret = 0;
+        if (context_present(context))
+                goto out_unlock;
 
         pgd = domain->pgd;
 
@@ -1928,11 +1922,10 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
          */
         if (translation != CONTEXT_TT_PASS_THROUGH) {
                 for (agaw = domain->agaw; agaw != iommu->agaw; agaw--) {
+                        ret = -ENOMEM;
                         pgd = phys_to_virt(dma_pte_addr(pgd));
-                        if (!dma_pte_present(pgd)) {
-                                spin_unlock_irqrestore(&iommu->lock, flags);
-                                return -ENOMEM;
-                        }
+                        if (!dma_pte_present(pgd))
+                                goto out_unlock;
                 }
 
                 info = iommu_support_dev_iotlb(domain, iommu, bus, devfn);
@@ -1971,7 +1964,12 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
                 iommu_flush_write_buffer(iommu);
         }
         iommu_enable_dev_iotlb(info);
-        spin_unlock_irqrestore(&iommu->lock, flags);
+
+        ret = 0;
+
+out_unlock:
+        spin_unlock(&iommu->lock);
+        spin_unlock_irqrestore(&device_domain_lock, flags);
 
         return 0;
 }
@@ -2214,9 +2212,12 @@ static inline void unlink_domain_info(struct device_domain_info *info)
 static void domain_remove_dev_info(struct dmar_domain *domain)
 {
         struct device_domain_info *info, *tmp;
+        unsigned long flags;
 
+        spin_lock_irqsave(&device_domain_lock, flags);
         list_for_each_entry_safe(info, tmp, &domain->devices, link)
-                dmar_remove_one_dev_info(domain, info->dev);
+                __dmar_remove_one_dev_info(domain, info->dev);
+        spin_unlock_irqrestore(&device_domain_lock, flags);
 }
 
 /*
@@ -4539,14 +4540,16 @@ static void domain_context_clear(struct intel_iommu *iommu, struct device *dev)
         pci_for_each_dma_alias(to_pci_dev(dev), &domain_context_clear_one_cb, iommu);
 }
 
-static void dmar_remove_one_dev_info(struct dmar_domain *domain,
-                                     struct device *dev)
+static void __dmar_remove_one_dev_info(struct dmar_domain *domain,
+                                       struct device *dev)
 {
         struct device_domain_info *info;
         struct intel_iommu *iommu;
         unsigned long flags;
         u8 bus, devfn;
 
+        assert_spin_locked(&device_domain_lock);
+
         iommu = device_to_iommu(dev, &bus, &devfn);
         if (!iommu)
                 return;
@@ -4556,9 +4559,7 @@ static void dmar_remove_one_dev_info(struct dmar_domain *domain,
         if (WARN_ON(!info))
                 return;
 
-        spin_lock_irqsave(&device_domain_lock, flags);
         unlink_domain_info(info);
-        spin_unlock_irqrestore(&device_domain_lock, flags);
 
         iommu_disable_dev_iotlb(info);
         domain_context_clear(iommu, dev);
@@ -4569,6 +4570,16 @@ static void dmar_remove_one_dev_info(struct dmar_domain *domain,
         spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
+static void dmar_remove_one_dev_info(struct dmar_domain *domain,
+                                     struct device *dev)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&device_domain_lock, flags);
+        __dmar_remove_one_dev_info(domain, dev);
+        spin_unlock_irqrestore(&device_domain_lock, flags);
+}
+
 static int md_domain_init(struct dmar_domain *domain, int guest_width)
 {
         int adjust_width;