x86/AMD-Vi: Fold exit paths of {enable,disable}_iommu()

... to avoid having multiple spin_unlock_irqrestore() calls.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Brian Woods <brian.woods@amd.com>

diff --git a/xen/drivers/passthrough/amd/iommu_init.c b/xen/drivers/passthrough/amd/iommu_init.c
index bb9f33e264b85532d83dc9698a25a54dbeff5c8f..bb5a3e57c93b2faa0dc27754fb9c53c81f58a013 100644 (file)
--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -899,11 +899,8 @@ static void enable_iommu(struct amd_iommu *iommu)
 
     spin_lock_irqsave(&iommu->lock, flags);
 
-    if ( iommu->enabled )
-    {
-        spin_unlock_irqrestore(&iommu->lock, flags); 
-        return;
-    }
+    if ( unlikely(iommu->enabled) )
+        goto out;
 
     amd_iommu_erratum_746_workaround(iommu);
 
@@ -957,6 +954,8 @@ static void enable_iommu(struct amd_iommu *iommu)
         amd_iommu_flush_all_caches(iommu);
 
     iommu->enabled = 1;
+
+ out:
     spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
@@ -966,11 +965,8 @@ static void disable_iommu(struct amd_iommu *iommu)
 
     spin_lock_irqsave(&iommu->lock, flags);
 
-    if ( !iommu->enabled )
-    {
-        spin_unlock_irqrestore(&iommu->lock, flags);
-        return;
-    }
+    if ( unlikely(!iommu->enabled) )
+        goto out;
 
     if ( !iommu->ctrl.int_cap_xt_en )
         amd_iommu_msi_enable(iommu, IOMMU_CONTROL_DISABLED);
@@ -988,6 +984,7 @@ static void disable_iommu(struct amd_iommu *iommu)
 
     iommu->enabled = 0;
 
+ out:
     spin_unlock_irqrestore(&iommu->lock, flags);
 }